Sample transfer device and method for analytical system

Abstract

An apparatus for chemical treatments has an enclosed vessel provided with lines for conveying samples and selectively openable valves in communication with sources of gases at atmospheric, increased, and reduced pressures. A plurality of such vessels may be combined, instead, in which case the pressure of the atmosphere in each vessel is made higher than that in the following vessel, so that the sample can be transferred to the following vessels. The vessel or vessels may be equipped with means for agitation, fixed-quantity sampling, liquid level detection, washing, filtration, extraction, thermostatic control, aeration, thermal concentration and distillation. An additional vessel equipped with pH-adjusting means and capable of maintaining an atmospheric pressure inside may be installed.

Description

This invention relates to an apparatus for chemical treatments, and more specifically to a chemical equipment for pretreating a sample of water by a chemical treating procedure, such as filtration, distillation, extraction, or color development, and then automatically performing a quantitive analysis of the sample's metallic and non-metallic contents by using an analyzer (or detector), for example, for the atomic absorption method or absorption spectrometry.

With the environmental destruction attracting more and more serious attraction, close monitoring of air and water pollution has been urgently called for. For the detection of water pollution and quantitative analysis of water quality, a number of methods are known. Most popular among them, in Japan, are the Testing Methods for Waste Water from Industrial Plants set forth in Japanese Industrial Standards K0102-1971, modified to conform to the Environmental Standards Concerning Water Pollution established by the Government on the basis of the Basic Law against Public Nuisances. [Other known methods include the Testing Methods for Industrial Waste Water, JIS-K0101, the methods defined in the Water-works Law (the Ministerial Ordinance Concerning Water Standards), and the Federal Water Quality Administration methods of the U.S.]

The JIS methods, all designed for manual control, are characterized in that each sample to be handled ranges in volume from 10 ml to 200 ml (or even 500 ml in some cases). From the viewpoint of the conveyance of samples in such volumes, the conventional methods have not proved satisfactory for the reasons to be explained later. Establishment of a new conveyance system has, therefore, been urgently needed for the perfection of automatic chemical analyses.

Characteristics features of existing features of existing automatic analyzers will now be briefly discussed with a primary emphasis laid on the conveyance of samples in ordinary pretreatment equipment.

One of the method uses a continuous flow divided by air bubbles into small-quantity portions. Wherein a reagent line merges with a main sample line and an air line is open into the sample line downstream of said merging point of the reagent line. All these lines are made of elastic material and the sample line and associated lines are squeezed by a squeeze pump having rollers to convey the contents forward, thereby air bubbles equidistantly join the flow of sample-reagent mixture to divide the same into equal portions. Thenceforth the sample-reagent mixture and air bubbles alternately form a stream and move altogether through the main sample line. This method has the following limitations. The sample pipe to be used must have an inner diameter small enough to avoid the disappearance of air bubbles therein, and this places an important limitation upon the quantity of the sample that can be handled. The arrangement is not adapted for such chemical treatment as extraction and dissolution of solids. The inside diameters of the lines which may be chosen are actually limited and only a few sizes are available. This confines the mixing ratio of the reagent and sample within a certain range. The pipes to be used must be elastic enough to endure squeezing and must be chemically stable to the sample and reagent to be encountered. Because of these limitations, some special method must be developed and adopted.

Another known method consists of retaining a sample in a container chemically treating the sample, and then transferring the sample to another place where it is to be subjected to another chemical treatment, either by moving the vessel or drawing up the sample by suction into the pipetter and discharging the same into another vessel. This method also has some limitations. It is impossible in this method to perform such chemical operations as extractive filtration, and distillation. The volume that the pipetter can handle is limited. The fact that the reaction vessels have to be moved together makes it necessary to handle only a small quantity of sample or even to adopt a special analytical procedure. The moving part of the equipment tend to be complicated in structure and increased in size. The sample is exposed to the atmosphere.

A third method known in the art is to convey a sample gravitationally by natural dropping. This method is characterized by the retention of the sample in a vessel during its chemical treatment and by the dependence upon natural downflow by gravity for the transport of the sample and the like. In this arrangement, the transfer lines must be held as vertically as possible and therefore the components parts that may be used are limited. Also a variety of samples cannot be smoothly handled. Each border of each reaction tank or the like requires a valve. To reduce the resistance of the pipes and valves is of value in facilitating the transport of the sample but brings a penalty of increased dead space, which in turn may cause undesirable intermingling of different samples when they are to be analyzed in succession.

From the standpoint of transport of samples, the existing automatic analyzers, classified by features into three types, have so far been briefly described.

The present invention has been perfected with the view to eliminating the foregoing disadvantages of the prior art equipment, and has for an object to provide a large-capacity apparatus for chemical treatments adapted for practicing a novel method of transporting fluids and capable of chemically analyzing many different samples.

Another object of the invention is to provide an apparatus for chemical treatments capable of automatizing all of the chemical analytical procedures that can be manually performed.

Still another object of the invention is to provide an apparatus for chemical treatments which can be increased in capacity and easily adapted for modifications in analytical procedures.

A further object of the invention is to provide an apparatus for chemical treatments capable of handling solid samples as well as fluid ones, with the system hermetically sealed.

Thus, according to the present invention, an apparatus for chemical treatments is provided which comprises closed vessels, groups of lines and selectively openable valves provided on the upper and bottom parts of the vessels for the conveyance of sample, an atmospheric-pressure gas source, an increased-pressure gas source, and a reduced-pressure gas source, said sources being communicated with said valve groups, one for each, said valve groups being selectively operated to control the pressure of the atmosphere in said vessels so that the sample can be transferred from the outside into the vessels or vice versa.

The foregoing and other objects and features of the invention will appear more fully from a reading of the following description taken in connection with the accompanying drawings, in which:

FIGS. 1 and 2 are diagrammatic views illustrating the conveyance of sample by a prior art technique;

FIGS. 3 and 4 are schematic sectional views of an automatic analyzer of a known type;

FIG. 5 is a schematic sectional view of an automatic analyzer of another known type;

FIg. 6 is a schematic view explanatory of the principle of fluid conveyance for the chemical apparatus according to this invention;

FIG. 7 is a schematic view illustrating connections for the apparatus of the invention;

FIG. 8 is a schematic view of a unit equipment of the apparatus according to the invention;

FIGS. 9 through 21 are schematic views of other unit equipments according to the invention;

FIG. 22 is a schematic view of an arrangement for chemical treatments embodying the invention; and

FIGS. 23 and 24a are diagrammatic sectional view of other forms of unit equipments embodying the invention and FIG. 24b is a sectional view along the line XXIVb--XXIVb of FIG. 24a.

Before explaining the present invention with reference to embodiments thereof shown in the drawings, the three methods employed in the existing automatic analyzers will now be described more definitely by referring to FIGS. 1 to 5.

FIGS. 1 and 2 schematically show the concept of the first prior method using a continuous flow divided by air bubbles into small-quantity portions. A reagent line 7 merges with a main sample line 6 at a junction 9, whereas an air line 4 is open into the sample line at a junction 10. A plurality of rollers 11, 11', are connected with chains 12 to constitute a squeeze pump, generally indicated at 13, which is driven in the direction indicated by an arrow in FIG. 2, so that the sample line 1 and the associated lines can be squeezed to convey the contents forward.

Since the pump 13 squeezes the pipes at a constant speed, the quantities of the sample and other fluids that flow through them depend primarily upon the inner cross sectional areas of the respective lines. Now it is assumed that a sample 1 runs in the sample line 6, a reagent 2 in the reagent line 7, and clean air 4 in the air line 8. The reagent 2 first merges into the sample 1 at the junction 9 to form a sample-reagent mixture 3, and then air bubbles 5 enter the mixture at the junction 10. The mixing ratio of the sample 1 to the reagent 2 is governed by the ratio of the inner cross sectional area of the sample line 6 to that of the reagent line 7. The air bubbles 5 equidistantly join the flow of the sample-reagent mixture 3 at the intervals dictated by the ratio of the inner cross sectional area of the air line 8 to the sum of the inner cross sectional areas of the sample line 6 and reagent line 7, thereby dividing the sample-reagent mixture 3 into equal portions. Each of the air bubbles 5 serves as a barrier wall to avoid intermixing of the adjacent sample-reagent mixture portions. Thenceforth the sample-reagent mixture 3 and air bubbles 5 alternately form a stream and move altogether through the main sample line 6.

In the manner described a reagent can be added at a suitably controlled rate to a continuous flow of sample, and a desirable period of time for a chemical reaction can be obtained through a judicious choice of line length. These lend themselves fundamentally to the automatization of chemical treatments. Because it permits chemical treatments of a sample in the course of transport through a sample line, the method renders it possible to extremely simplify the construction and reduce the size of the equipment for pretreatments of the sample. The reagent and sample which run through fluidtightly sealed lines, cannot be contaminated by any outside source. On the other hand, the method has certain limitations. If any bubble keeping apart two sample-reagent mixture portions of different compositions should break, the two liqud portions would be intermingled, thus interrupting the testing procedure. For this reason the sample pipe to be used must have an inner diameter small enough to avoid the disappearance of air bubbles therein. Practically the upper limit of the diameter is about 5 mm, and this places an important limitation upon the capacity of the sample line, or the flow rate of the sample that can be handled. In addition, the arrangement is not adapted for such chemical treatments as extraction and dissolution of solids. The inside diameters of the lines which may be chosen are actually limited and only a few sizes are available. Consequently the mixing ratio of the reagent and sample is confined within a certain range. The pipes to be employed must be elastic enough to endure squeezing and must be chemically inert to the sample and reagent to be encountered. Because of these requirements, some special method must be developed and adopted. Thus, as compared to other approaches, the method has major limitiations in limitations chemical analyses involved and in the accuracy or reliability of the results.

FIGS. 3 and 4 schematically represent the concept of the second known method consisting the steps of retaining a sample in a container, chemically treating the sample, and then transferring the sample to another place where it is to be subjected to another chemical treatment, either by moving the vessel or drawing up the sample by suction and discharging the same into another vessel. As shown, reaction vessels 26a, 26b, 26c are connected with chains 27 in an orderly manner and are moved stepwise by drives (not shown) in the direction indicated by an arrow. A pipetter, designated 28, is capable of drawing up by suction the contents of a reaction vessel or discharging the contents into an empty vessel through a nozzle 29 equipped with drives (not shown) for its vertical and horizontal movements. A dispenser 24 is operatively connected to two valves 25, so that a reagent 22 from a reagent bottle 33 can be admitted into a reaction vessel via lines 31, 32 and through a nozzle 30 equipped with drives (not shown) for its vertical movement. The nozzle 30 may be independent of the nozzle 29 or may be connected thereto with a bridging tube 34.

On an automatic analyzer of the type described, the sample can be transferred from one place to another where another chemical operation is to be performed, in either of two ways. One way is to cause the pipetter 28 to draw up by suction the contents of a reaction vessel (e.g., the vessel 26b) by way of the nozzle 29, and then move the nozzle 29 to a point above another reaction vessel (e.g., 26c) and allow it to discharge the liquid into the latter vessel. The other is to take up the nozzles 29, 30 of the pipetter 29 and dispenser 24 from the reaction vessel and move the group of reaction stepwise by drives in the direction indicated by an arrow (that is, from the positions shown in FIG. 3 to those in FIG. 4). In either case, the reagent 22 can be added to the sample 21 by means of the dispenser 24 and the chemical reaction time can be controlled by adjusting the time intervals for the horizontal movement of the pipetter nozzle 29 or for the movement of all the reaction vessels. These possibilities provide bases for the automatization of operations for chemical analyses.

According to the method, a chemical treatment is carried out with the sample retained in a reaction vessel and the transfer of the sample is accomplished by moving the vessel containing the same. This presents an advantage of simplicity in the analytical operation and hence in the fundamental construction of the apparatus, and provides an additional advantage of the containment of different samples in independent vessels which precludes intermingling of the samples. On the other hand, it is impossible with this arrangement to perform such chemical operations as extractive filtration, and distillation. The volume that the pipetter can handle is limited. The fact that the reaction vessels have to be moved together makes it necessary to handle only a small quantity of sample, or even to adopt a special analytical procedure. The moving parts of the equipment tend to be complicated in structure and increased in size. Among the other disadvantages is the exposure of the sample to the atmosphere.

FIg. 5 schematically represents the concept of the third method known in the art in which a sample is conveyed gravitationally by natural dropping. Reaction tanks 48, 49 are communicated to each other by pipes 50, 51 open in the respective tanks, with a valve 53 for shutoff purpose installed between the two pipes. The tanks 48, 49 are formed with vents 57, 58, which are open in the atmosphere. A sample storage tank 56 is communicated to the upper part of the reaction tank 48 with pipes 52, 55, which are open in the respective tanks and are separated by a valve 54 installed midway. A dispenser 43 is operatively connected to valves 44 to enable the reagent 41 from a reagent bottle 47 to flow into the reaction tank 48 via pipes 45, 46.

Opening the valve 54 allows the sample 40 to run down gravitationally, at a controlled rate, into the reaction tank 48 through the pipes 52, 55. Meanwhile a given quantity of the reagent 41 is added to the sample in the reaction tank 48 by means of the dispenser 43, the addition being followed by a certain waiting period. These functions constitute some requisites for chemical analyzing operations. If necessary, the sample-reagent mixture 42 is conveyed by gravity through the pipe 50, valve 53, and pipe 51 into the lower reaction tank 49.

This third method is characterized by the retention of the sample in a vessel during its chemical treatment and by the dependence upon natural downflow by gravity for the transport of the sample and the like, which eliminates power requirement. This means, however, that the transfer lines must be held as vertically as possible and therefore the component parts that may be used are limited. A variety of samples cannot be smoothly handled. Each border of each reaction tank or the like requires a valve. To reduce the resistances of the pipes and valves is of value in facilitating the transport of the sample but brings a penalty of increased dead space, which in turn may cause undesirable intermingling of different samples when they are to be analyzed in succession.

With reference specifically to FIG. 6, the fundamental principle of the present invention will be described hereunder. The method of transporting a sample in the apparatus for chemical treatments in accordance with this invention is to convey the sample by controlling the atmosphere surrounding the same, that is, by changing it pressure to atmospheric, positive or negative one. Here, numerals 61, 73 indicate reaction tanks wherein sample mixtures are retained and subjected to chemical treatments. They are equipped with auxiliary means so that they can perform practically analogous functions. In the upper parts of the reaction tanks 61, 73 are open sample lines 62, 74, the other ends of which are connected to sampleline valves 63, 75 for opening and closing the lines. Sample-drain pipes 64, 76 are open in the lower parts of the reaction tanks 61, 73 and, on the other ends of these pipes, sample-line valves 65, 77 and waste-liquid line valves 72, 84 are installed as shown. The sample-line valves 65, 75 are connected via sample pipe 741. One end of each of manifolds 66, 78 is open in the upper parts of the reaction tanks 61, 73. Three ports in the other parts of the manifolds are provided with atmospheric-pressure line valves 67, 79, increased-pressure line valves 68, 80, and reduced-pressure line valves 69, 81. Reagent inlet pipes 70, 82 are open in the upper parts of the reaction tanks 61, 73, and reagent inlet valves 71, 83 are installed at the other ends of pipes 70, 82.

The reaction tanks 61, 73 equipped with the groups of pipes and valves above described constitute closed reaction tank units 501, 502, respectively.

For their operations these reaction tank units are connected to necessary pipe groups and necessary external sources. A sample pipe 85 is connected to the sample-line valve 63 and is in communication with a sample reservoir (not shown) at the atmospheric pressure or an increased pressure. Atmospheric-pressure pipes 86a, 86b are preferably open in the atmosphere through filters or are communicated with an inert-gas reservoir (not shown) at the atmospheric pressure, because the reaction tank units form closed systems. Increased-pressure pipes 87a, 87b are likewise in communication through filters to a clean-air or inert-gas source (not shown) under pressure (positive pressure) of 0.01-1 kg/cm.sup.2 G. Reduced-pressure pipes 88a, 88b are connected to a reduced-pressure (negative pressure) source (not shown), desirably at a pressure between -0.01 and 0.5 kg/cm.sup.2 G. Waste-liquid pipes 89a, 89b communicate with a suction source (not shown) at a pressure between -0.01 and 0.5 kg/cm.sup.2 G, which constantly draws up by suction the liquid or gas that flows through the pipes.

The procedure for feeding samples to these reaction tank units will now be explained. Unless otherwise specified, it should be understood that all valves in the vavle groups are closed. In order to introduce a sample into the reaction tank 61, it is only necessary to open the sample-line valve 63 and atmospheric-pressure line valve 67 if the sample reservoir is kept under pressure or, if the pressure in the reservoir is atmospheric, the sample-line valve 63 and reduced-pressure line valve 69 have only to be opened, so that the pressure in the reaction tank 61 is reduced to attract the sample into the vessel. In either case, all valves are closed after a predetermined amount of sample has been fed to the reaction tank 61 and, immediately thereafter, the atmospheric-pressure line valve 67 is temporarily opened to maintain the atmospheric pressure in the tank. Transference of the sample from the reaction tank 61 to the tank 73 may be accomplished in either of two ways. One is to enable the reaction tank 73 to have a passive function (after which the procedure is hereinafter called the "passive transference"). In this procedure the increased-pressure line valve 68, sample-line valves 65, 75, and atmospheric-pressure line valve 79 are opened. Now that the sample-line valves between the two reaction tanks are open, the sample-line is open, too, and the sample in the reaction tank 61 is forced down into the reaction tank 73 by the increased pressure (positive pressure) being exerted from the above liquid level in the tank 61. The sample admitted into the reaction tank 73 is, of course, kept at the atmospheric pressure. If it is assumed that the flow passage between the two reaction tanks is equivalent to a pipe 2.4 mm in inside diameter and 20 cm in length, then 100 ml of water will be transferred from the former to the latter in about 20 seconds by simple exertion of a positive pressure of about 0.1 kg/cm.sup.2 on the increased-pressure pipe 87a.

The other procedure is to permit the reaction tank 73 to have an active function (hereinafter called the "active transference"). This time the atmospheric-pressure line valve 67, sample-line valves 65, 75, and reduced-pressure line valve 81 are opened. Communication is thus established between the two reaction tanks and, because the pressure in the tank 73 is reduced (negative) whereas the sample in the tank 61 is at the atmospheric pressure, the sample is conveyed from the tank 61 to 73. If the passage and conditions for the conveyance of the sample are the same as in the passive transference, then a negative pressure of about 0.1 kg/cm.sup.2 applied to the reduced-pressure pipe 88b will be sufficient to effect the conveyance. Here it is appreciated that the passive transference to the reaction tank 73 means the active transference from the tank 61 and vice versa. Therefore, the afore-described method of supplying the sample to the reaction tank 61 with the reduced-pressure line valve 69 opened corresponds to the active transference to the tank 61. Whichever procedure is followed, the pressure in the vessel after the supply of the sample is kept positive or negative for an excess period of time, so that any sample that may have adhered to the surrounding wall of the passage is blown off clearly by the stream of air or inert gas. Consequently there is no possibility of undesirable intermingling of different samples along any relatively long passage. This is another major advantage of the transference by this procedure. When the sample in the reaction tank 73 is to be transferred to some other place, the increased-pressure line valve 80 and sample-line valve 77 have only to be opened in order that the reaction tank 73 may accomplish the active transference. If any waste material is to be delivered out for abandonment from either the reaction tank 61 or 73, it is merely necessary to open the waste-liquid line valve 72 or 84 and atmospheric-pressure line valve 67 or 79 as the case may be, and then drain the waste material into the waste-liquid line 89a or 89b which is ready to draw in the waste by suction. As an alternative to this passive transference for the either tank, the active procedure may be resorted to by opening the waste-liquid line valve and increased-pressure line valve of the particular tank.

The reaction tank units 501, 502 are provided with reagent lines (not shown) through which and the reagent inlet valves 71, 83 a reagent or reagents can be supplied from reagent bottles. The reagent or reagents can be added to the samples in the tanks by the passive or active transference and with the use of the reagent inlet valves 71, 83. This, when combined with the contollability of the length of time for which the sample is retained in either reaction tank or the both, will provide the basis for automatization of treatments for chemical analyses.

It is to be noted that the sample pipe 741, if cut off midway, will provide two identical reaction tank units 501, 502. Each of these units comprises a reaction tank, a sample pipe (for sample feeding) and a valve installed on the upper part of the tank, a sample pipe (for sample discharging) and a valve on the lower part, and a group of valves and lines provided above the vessel to make the pressure therein positive, atmospheric, or negative for the purpose of sample conveyance. Considering these reaction tank units as unit equipments each combining active and passive functions, it follows that the units can be connected both in series and parallel. Any unit equipment may be disconnected from, or may be added to, any of complex combinations of unit equipments, without affecting the function of the original combination and that of the automatic controls including the valves.

Aside from the reaction tank units taken as examples of unit equipments in the foregoing description, such other chemical apparatus as filters, aerators, thermal distillers, thermal concentrators, agitators, pH-adjusters, extractors, separators, and dissolvers may fall into the domain of units of which the present invention is equally applicable. If the sample container of any such units enumerated above is combined with groups of pipes and valves for sample conveyance and groups of valves and pipes for making the pressure in the vessel positive, atmospheric, or negative so as to convey the sample just in the same way as with a reaction tank unit, then such a chemical apparatus will be interchangeable with any of the reaction tank units.

Briefly stated, combination of the automatic control of such unit equipments with that of sample conveyance provides automatic control of every operation for chemical treatment.

Serial connection of reaction tank units has already been described in connection with the fundamental principle of the present invention. Next, parallel connection of the reaction tank units in an embodiment of the invention and the procedure for sample transference involved will be explained with reference to FIG. 7. For the sake of simplicity, reagent inlet pipes and valves are omitted from all of the reaction tank units illustrated. A first reaction tank unit 503, like the tank units already described, comprises a reaction tank 91, sample pipe 92, sample-line valve 93, sample-drain pipe 94, atmospheric-pressure line valve 95, increased-pressure line valve 96, reduced-pressure line valve 97, and waste-liquid line valve 98. It differs from the reaction tank units 501, 502 in that the sample-drain pipe 94 is not terminated with a sample-line valve but is connected to a tee 116. Second and third reaction tank units 504, 505 are quite similar to the units 501, 502 shown in FIG. 6. Smaple-line valves 103a, 103b of these reaction tank units are communicated with a tee 117, so that the tank units 504, 505 are on equal terms with the first unit 503. A fourth reaction tank unit 506 comprises a reaction tank 108, sample pipe 109, sample-line valve 111, atmospheric-pressure line valve 112, increased-pressure line valve 113, reduced-pressure line valve 114, and waste-liquid line valve 115. The sample pipe 109 communicates to the tee 117 instead of a sample-line valve. The tee 117 is in communication with the sample-line valves 103a, 103b. Stated differently, the second reaction tank unit 504 and the third unit 505 are disposed between and in parallel to the first and fourth units 503, 506. Description of the pipe groups and external supply sources will be omitted hereinafter because, unless otherwise stated, they are in essence the same as those already described in connection with the fundamental principle of this invention.

It is now assumed that in operations involving three-step chemical treatment the treating time required for the first or third step is a half of the period for the second step. In this case the reaction tank units are desirably connected as illustrated in FIG. 7. Unless otherwise stated, all valves are construed to remain closed. First, the sample is introduced into the reaction tank unit 503 by the active transference, that is, by opening the sample-line valve 93 and reduced-pressure line valve 97 and thereby reducing the pressure in the tank 91. After the introduction, the atmospheric-pressure line valve 95 is once opened to increase the pressure of the sample to the atmospheric level, and then the first-step chemical treatment is carried out. Next, the sample is transferred to the second reaction tank unit 504. As noted already, the transference may be accomplished in either of two ways. One method is, in this case, the passive transference to the reaction tank unit 504, whereby the increased-pressure line valve 96, sample-line valve 101a, and atmospheric-pressure line valve 104a are opened to place the sample inside the reaction tank 91 under an increased pressure. The other is the active transference to the same unit 504 whereby the atmospheric-pressure line valve 95, sampleline valve 101a, and reduced-pressure line valve 106a are opened. In the subsequent increased-pressure or reduced-pressure operations with the other reaction tanks or sample containers to be mentioned later, it is to be noted that, unless otherwise specified, the atmospheric-pressure line valve is once opened to maintain the pressure in the vessels at the atmospheric level. Here the second-step chemical treatment is effected. Since the time required for the second step treatment is twice as much as for the first step, the first reaction tank unit 503 is allowed to repeat the first-step treatment with another sample while, at the same time, the second step is in progress. The first sample is then transferred to the third reaction tank unit 505 in the same manner as when it was conveyed from the first unit 503 to the second 504, except that the sample-line valve 101b is employed this time. During this, the second-step treatment is repeated. As will be explained later, the method of sample transference is limited to one, passive or active, depending upon the type of unit equipment to be employed for a particular chemical treatment or upon the type of sample or reagent to be handled. The sample is then transferred from the second reaction tank unit 504 to the fourth unit 506. Again, two alternatives are open. One is the passive transference to the unit 506, whereby the increased-pressure line valve 105a, sample-line valve 103a, and atmospheric-pressure line valve 112 are opened to convey the sample. The other is the active transference whereby the atmospheric-pressure line valve 104a, sample-line valve 103a, and reduced-pressure line valve 114 are opened for the conveyance purpose. In this stage the third-step chemical treatment is performed. The increased-pressure line valve 113 and sample-line valve 111 are opened and, by this active transference from the unit 506, the sample is transferred elsewhere. In order to transfer the sample from the reaction tank 99b to the tank 108, it is simply necessary to use the sample-line valve 103b and resort to the passive or active transference from the reaction tank unit 506 in the manner above described. If any undesired residue (such as the washings to be described later) is found in any reaction tank unit, it may be discharged into the waste-liquid line by opening the waste-liquid line valve and following the procedure for passive or active transference from the particular tank unit.

Although the example given above uses a pair of reaction tank units for parallel connection, it should be obvious from the description of the principle of this invention that more reaction tank units may be connected in parallel or, as a further alternative, groups of serially connected units may be connected altogether in parallel.

In the foregoing description the reaction tank units have been regarded as components of a unit equipment. Now that equipments having separate functions of chemical treatments will be considered.

One of such unit equipments is a unit for the addition of a reagent, as schematically illustrated in FIG. 8. A sample pipe 132 is open in the upper part of a reaction tank 131 and is connected at the other end to a sample-line valve 133. A sample-drain pipe 134 which is open in the lower part of the reaction tank 131 is communicated with a sample-line valve 135 and a waste-liquid line valve 141. A manifold 136 which is open in the upper part of the tank communicates to an atmospheric-pressure line valve 137, an increased-pressure line valve 138, and a reduced-pressure line valve 139. A reagent line that extends from a reagent bottle (not shown) through valves 142, which are operatively connected to a dispenser 143, terminates in the form of a reagent pipe 140, which in turn is open in the upper part of the reaction tank 131. If agitation is required, an agitator consisting, for example, of an agitation blade 144 inside the tank and an external magnetic stirrer 145, may be installed. In this way a reagent-addition unit 507 is constructed.

The operation, function, and performance of this unit 507 will be described later hereunder. Here again the description of the lines and external supply sources required for the operation will be omitted because they are essentially the same as those which have already been described. Also, unless otherwise stated, it should be appreciated that all valves are normally closed and the reaction tank or other vessel to be described later is hermetically sealed. The same applies to all of the equipments to be described later and, therefore, these provisos will be omitted for brevity from the the following description.

First, the sample-line valve 133 and atmospheric-pressure line valve 137 or reduced-pressure line valve 139 are opened to admit the sample into the reaction tank 131 by the passive or active transference to the reaction tank unit 507. After the transference, the atmospheric-pressure line valve 137 is opened for some time to maintain the sample at the prevailing atmospheric pressure. Next, while the valve 137 is kept open, the valves 142 operatively connected to the dispenser 143 are manipulated, so that a given amount of the reagent can be added to the sample by way of the reagent pipe 140. This may be effected, if necessary, while the magnetic stirrer 145 is being driven and the sample-reagent mixture is being agitated by the blade 144.

For the addition of the reagent, a valve such as indicated at 71 in FIG. 6 may be employed provided that the given amount of the reagent can be measured into the tank by some suitable means. Importantly, the valve to be used must be capable of hermetically closing the reagent-addition unit, even on a temporary basis. Also it should be clear that, while one type of reagent is handled in the unit being described, many different reagents may be added, instead, in a similar way.

After the reagent and sample have thoroughly reacted with each other (usually with the atmospheric-pressure line valve 137 closed, although the valve must be kept open for certain reaction systems), the atmospheric-pressure line valve is closed and agitation is discontinued. In order to transfer the reaction product to some other place, either the passive or active transference from the reaction tank unit 507 is effected by opening the sample-line valve 135 and atmospheric-pressure line valve 137 or increased-pressure line valve 138. If useless sample is to be discarded, the waste-liquid line valve 141 is used in lieu of the sample-line valve 135.

Another example of unit equipment is a fixed-quantity sampling unit 508, as schematically shown in FIG. 9. A sample-line valve 153 is installed in communication with a sample pipe 152, which in turn is open in the upper part of a container 151. A sample-drain pipe 154 open at one end in the lower part of the container 151 is communicated at the other end with a sample-line valve 155 and a waste-liquid line valve 159. In communication with a manifold 156 which is open in the upper part of the container 151, there are installed an atmospheric-pressure line valve 157 and an increased-pressure line valve 158. A nozzle 160 is open in a suitable position inside the container via a gastight seal (not shown) capable of moving up and down in the upper part of the vessel. The other end of the nozzle communicates to a line 162 through a valve 161. Such is the construction of a fixed-quantity sampling unit 508. The line 162, inside of which is kept at a reduced pressure by some suitable means, attracts fluid, either liquid or gas.

The operation of this fixed-quantity sampling unit 508 will now be explained. The sample-line valve 153 and valve 161 are opened first. This results in a reduced pressure inside the container 151, and the sample begins to be conveyed through the pipe 152 into the vessel. Once the sample level has reached the opening of the nozzle 160, any excess of the sample is drawn up by suction into the line 162 through the nozzle 160 and valve 161, with the consequence that the liquid level of the sample 163 is kept constant. Even if the sample level has temporarily exceeded the opening of the nozzle 160, the excess sample will be taken up by the nozzle 160 when the sample-line valve 153 is closed while, at the same time, the atmospheric-pressure line valve 157 is opened. As a result, the liquid level of the sample 163 will be maintained constant. The opening position of the nozzle 160 may be preset so that a predetermined amount of the sample 163 can be held within the container. When considering this sampling method with the valve 161 replaced by a reduced-pressure line valve, it is appreciated that the method is tantamount to the active transference to the sampling unit 508. The measured amount of the sample 163 is either transferred to some other place or abandoned by the active transference from the unit by opening the increased-pressure line valve 158 and sample-line valve 155 or waste-liquid line valve 159.

This fixed-quantity sampling unit may be utilized to collect the supernatant fluid from a solution containing sediments, in which case the opening position of the nozzle 160 has only to be chosen so that the portion of the liquid which tends to be relatively easily clarified can be collected.

The third example of unit equipment is a dilution unit, either of a photoelectric type or an electric conductivity type, as schematically represented in FIG. 10 or 11, respectively. The unit shown in FIG. 10 will be described first. In the upper part of a reaction tank 171 is open a sample pipe 172 which is equipped with a sample-line valve 173. In the lower part of the tank 171 is open a sample-drain pipe 174, which in turn communicates to a sample-line valve 175 and a waste-liquid line valve 182. A manifold 176 open at one end in the upper part of the tank 171 is also in communication with an atmospheric-pressure line valve 177, an increased-pressure line valve 178, and a reduced-pressure line valve 179. From the bottom of a reagent bottle 186, a reagent pipe 180 extends downward through a valve 181 and opens in the reaction tank 171. Further, along both sides of the tank there are located a light source 183 and a light-beam detector 184, in positions opposite to each other and in such a way that they can be moved up and down by some suitable means (not shown) with respect to the tank 171. Signals from the light-beam detector 184 are sent to a controller 185, so that the sample-line valve 181 can be opened or closed depending upon the presence or absence of the detection signals. Such is the construction of a dilution unit 509.

The unit is operated in the following manner. It is assumed that the reaction tank 171 is filled with a given quantity of sample by the procedure already described in connection with the reagent-addition unit, and that the sample is to be diluted, for example, with water. The light source 183 and light-beam detector 184 are located on a level equal to that of the liquid after dilution. The optical instrument of this type detects the deflection of the path of a light beam from the source 183 due to the difference between air and the sample (liquid), in terms of ON-OFF signals on the detector 184. The controller 185 is so adjusted that, when there is a predetermined amount of the sample in the reaction tank 171, the valve 181 is kept open and the reagent (mere water in this case) is allowed to drop from the bottle 186 into the reaction tank 171 until the liquid level of the sample in the tank comes up to the light path. In this manner the reagent (or water) is added only when there is a predetermined amount of the sample in the reaction tank or, in other words, dilution to a predetermined level is accomplished. In exemplary operations, the errors in dilution were in the range of plus or minus 0.2% per 100 ml of the diluted solution.

The arrangement shown in FIG. 11, or the electric conductivity type, differs from the type of FIG. 10 in the method of detecting the liquid level after the dilution as specified. The type of FIG. 10 detects the level optically, whereas that of FIG. 11 detects it by means of an electrode that forms a part of an electric circuit. The electrode, indicated at 203, consists of a glass tube or the like and two wires of platinum or the like insulated and enclosed in the glass. It is vertically movable in the upper part of a reaction tank 191 while hermetically sealing the tank. A controller 204 comprises the electric circuit including the electrode 203 as one of its components, and functions so that, when there is the sample to be diluted in the reaction tank 191, the controller cooperates with the electric circuit to open a reagent inlet valve 201 and admit the reagent (e.g., water) into the reaction tank and, when the liquid level of the diluted sample has reached the electrode 203, it closes the reagent inlet valve 201. The electric circuit is used to detect the difference between the electric conductivities of the air and the sample between the element wires of the electrode 203. In other words, the circuit is of the electric conductivity type. The components described above are assembled to form a dilution unit 510.

The electric conductivity system of the dilution unit 510 works in the manner now to be described. It is assumed that the reaction tank 191 is prefilled with a given amount of the sample and that the sample is to be diluted to a certain volume with the addition, for example, of water. The electrode 203 is installed at the height corresponding to the liquid level after the dilution. The controller 204 opens the reagent inlet valve 201 in response to a signal from the outside, so that the reagent (or water in this case) is admitted into the reaction tank 191. If necessary, the sample may be agitated by an agitator (not shown). Initially the electric conductivity between the electrode wires is zero (because air is an insulator) but, as the liquid surface of the sample having a certain specific conductivity comes into contact with the electrode wires, the controller 204 closes the sample inlet valve 201, thus completing the dilution. In exemplary experiments, the accuracy of dilution with this unit 510, as well as with a dilution unit of a high-frequency transmission type, was less than plus or minus 0.2% for the sample volume of 100 ml, where a reagent inlet pipe 200 having an inside diameter of 2.4 mm was employed.

Dropwise introduction of the reagent into the reaction tank 171 may be effected in two ways; either by opening only the atmospheric-pressure line valve 177 and allowing the reagent to flow down by gravity, or by opening only the reduced-pressure line valve 179 and thereby reducing the pressure in the reaction tank 171.

The fourth example of unit equipment is a washing unit, as schematically shown in FIG. 12. It is more practical to employ this washing unit as a washer for a reaction tank or container of another unit equipment than to consider it as a unit equipment. However, for the simplicity of explanation, it is taken here as an independent unit equipment. It will be seen from the foregoing description about the three different unit equipment that those units have many parts in common. The illustration and description of the common parts do not appear essential for the explanation of the functional principles of the unit equipments and, therefore, will be omitted hereinafter.

Reference numeral 211 indicates a reaction tank, and a waste-liquid line valve 213 communicates to a sample-drain pipe 212, which in turn opens in the lower part of the tank. A manifold 214, open in the upper part of the reaction tank 211, is communicated also with an atmospheric-pressure line valve 215 and an increased-pressure line valve 216. Close to the upper end of the chamber inside the tank there is installed a washing nozzle 217, which has at its lower end a sprinkler 218 and is connected at the other end with a change-over valve 219. This valve is so designed that when it remains closed as well as other valves, the reaction tank 211 is hermetically sealed. Alternatively, another valve (not shown) may be installed midway the washing nozzle 217 instead of using the change-over valve 219 of the construction just described above. In the arrangement shown, changing over the valve 219 can establish communication between the washing nozzle 217 and either a washing-solution A line 220 or a washing-solution B line 221. Those lines 220, 221 are connected to respective washing-solution reservoirs (not shown) with or without an additional pressure applied to the liquids therein. These components make up a washing unit 511.

The function of this washing unit 511 and the washing method adopted will be described below. By way of explanation the inner wall of the reaction tank 211 is assumed to be contaminated. From the viewpoint of introduction of the washing solution, the washing operation can be carried out in a number of ways. In one procedure, the waste-liquid line valve 213 and atmospheric-pressure line valve 215 are opened to allow the contaminant to drain from the reaction tank 211 into the waste-liquid line (not shown) wherein the partial vacuum continues to provide suction as well as in the reaction tank. Next, the change-over valve 219 is manipulated (to the position in FIG. 12) where it communicates the washing nozzle 217 to the washing-solution A line 220 at an increased pressure or at the prevailing atmospheric pressure. The washing solution A introduced through the washing nozzle 217 is then scattered by the sprinkler 218 to wash the inner wall surface of the reaction tank and flow down into the waste-liquid line (when, if necessary, the atmospheric-pressure line valve 215 may be closed.) Instead of this washing with running liquid, it is also possible to use the washing solution in a retained state. For this purpose the waste-liquid line valve 213 is closed and the atmospheric-pressure line valve 215 is opened so that the washing solution A under pressure or at the atmospheric pressure can be led through the change-over valve 219 and collected in the reaction tank 211. Following the washing, with agitation where necessary, the washings are allowed to drain in either of two ways. The waste-liquid line valve 213 and atmospheric-pressure line valve 215 are opened and the washing are caused to flow down into the waste-liquid line wherein the suction still prevails. Or, the atmospheric-pressure line valve 215 is closed and the increased-pressure line valve 216 and waste-liquid line valve 213 are opened to flow down the washings. If the washing solution A alone cannot wash well, the change-over valve 219 may be manipulated to use the washing solution B, too. Of course, three or more different washing solutions may be used in this manner. For example, in the case of the hydroxides in river water that precipitate on the alkaline side of pH 10 in a reaction tank capable of treating 100 ml of the sample, mere distilled water cannot thoroughly wash the deposits away. It is customary in such occasion to dissolve the deposits with a dilute acid and then wash away the acidic solution with distilled water. In this manner thorough washing is accomplished.

Still another example, the fifth, of unit equipments is hydrogen-ion-concentration (pH)-adjusting unit. FIG. 13 illustrates the unit schematically. For the pH adjustment, usually a commercially available pH meter equipped with an automatic titrator is used. In order to simplify the construction of the reaction tank a composite glass electrode is advantageously employed. In general, such a glass electrode must not be used in an atmosphere at a positive or negative pressure, because the non-atmospheric pressure can cause undesirable intermixing or mutual contamination of the sample and the aqueous solution of a salt which is a constituent of the glass electrode. For this reason the pH-adjusting unit, as a principle, requires, in addition to the reaction tank in which the glass electrode for pH measurement is inserted, two other reaction tanks, one in front and the other behind. In order that the sample be conveyed into the center tank, the two extra tanks must have active functions whereas the center tank equipped with the glass electrode must function passively.

Referring to FIG. 13, numeral 241 indicates a reaction tank. A sample pipe 242 is open, via a sample-line valve 243, in the upper part of the tank. In the lower part of the tank 241 is open a sample-drain pipe 244, which in turn is communicated with a sample-line valve 245. Further, a manifold 246 is open in the upper part of the reaction tank 241 and is also communicated with an increased-pressure line valve 247. The unit constructed in this way is a sample-pressurizing unit 512a for transferring a sample to a pH-adjusting tank 512b now to be described. The latter unit comprises a reaction tank 248, having a sample pipe 249 which is open in the upper part of the tank and is communicated at the other end with a sample-line valve 245. A sample-drain pipe 250 open in the lower part of the reaction tank 248 communicates to a sample-line valve 251. A manifold 252 open in the upper part of the tank 245 communicates to an atmospheric-pressure line valve 253. In addition, a composite glass electrode 256 of commerce is inserted into the reaction tank 248 through a vertically movable sealer (not shown) which establishes a gastight seal in the upper part of the tank 245. This composite electrode communicates to the front end of an automatic titrator of a pH meter (both not shown) equipped with the titrator of which the electrode forms a part. Via a reagent inlet valve 255 a reagent pipe 254 is open in the upper part of the reaction tank 248. These components constitute the pH-adjusting tank 512b. In this tank 512b is placed an agitator blade 257, which is driven by external means, such as a magnetic stirrer (not shown) installed outside, for the agitation of the sample. Another reaction tank 258 has a sample pipe 259 which is open in the upper part of the tank while in communication with the sample-line valve 251. A sample-line valve 261 is installed in communication with a sample-drain pipe 260, which in turn opens in the lower part of the reaction tank 258. A manifold 262 which opens in the upper part of the tank communicates to a reduced-pressure line valve 263. The unit so constructed is a sample-pressure reducing unit 512c for removing the sample from the pH-adjusting tank 512b. The sample-pressurizing unit 512a, pH-adjusting tank 512b, and sample-pressure reducing unit 512c are combined to form the pH-adjusting unit. In many cases the sample-pressurizing unit and sample-pressure reducing unit are employed in common with another unit equipment.

The operation of this pH-adjusting unit will now be explained. By way of illustration, it is assumed that the sample-pressurizing unit 512a is filled with the sample whose pH is to be adjusted. First, the increased-pressure line valve 247, sample-line valve 245, and atmospheric-pressure line valve 253 are opened, so that the pressure on the liquid surface of the sample in the reaction tank 241 is increased and the sample is forced out through the sample-drain pipe 244, sample-line valve 245, and sample pipe 249. By this active transference from the reaction tank 241, the sample is transferred to the reaction tank 248. The latter tank, in which the pH-adjusting glass electrode 256 is inserted, does not permit either an increase or decrease in pressure (to positive or negative pressure) as has already been noted. Since the atmospheric-pressure line valve 253 is open, normal atmospheric pressure is maintained in the reaction tank 248. After the sample has been completely transferred from the reaction tank 241 to 248, the sample pipe 249 is cleaned with a jet of air (or, if necessary, with a jet of an inert gas). At this time all valves are closed and, if necessary, the atmospheric-pressure line valve 253 is opened to keep the pressure inside the reaction tank 248 atmospheric. Following this, the pH meter is actuated by a signal indicating, for example, that the increased-pressure line valve 247 has been closed. If the pH value of the sample is yet to reach a predetermined level, the titrator automatically works and controls the reagent inlet valve 255, thus allowing a pH-adjusting reagent to drop from the reagent inlet pipe 254. During this period the atmospheric-pressure line valve 253 is kept open. If necessary, the agitator blade 257 may be operated by drives located outside so as to agitate the sample. Upon arrival of the pH of the sample at the predetermined value, the titrator stops automatically and the reagent inlet valve 255 closes, thus completing the pH adjustment. In order to transfer the sample whose pH has been adjusted from the reaction tank 248 to 258, the active transference to the latter tank is resorted to by opening the atmospheric-pressure line valve 253, sample-line valve 251, and reduced-pressure line valve 263. Subsequently the sample pipe 259 is cleaned by a jet of air. As described above, the sample-pressurizing unit 512a and sample-pressure reducing unit 512c having active functions for the conveyance of the sample are located at the front and rear of the pH-adjusting tank 512b, whereby the pressure inside the pH-adjusting tank 512b can be kept at the atmospheric level.

A filtration unit is the sixth of the unit equipments that may embody the present invention. Schematically shown in FIG. 14 is a unit of a filter paper type and shown in FIG. 15 is a filter board type. The former type will be detailed first. In principle the filter paper type is so constructed that a sheet of commercially available filter paper, cut to a suitable shape, is kept in close contact with a seat of a suitable shape and, after the filtration of a sample, the paper is abandoned. Reference numeral 271 indicates a container for the sample to be filtered. The container is open at the top and receives the lower end of a sample pipe 272, which in turn is equipped with a sample-line valve 273. A drain pipe 274 open in the lower part of the container 271 is equipped with a waste-liquid line valve 275. A funnel 281 has at its lower end a filter seat 276 of a suitable shape, for example in the form of a cone. One end of a sample pipe 277 is open in this seat 276. The upper end of the funnel 281 has an annular space wherein a washing sprinkler nozzle 279 formed with a multiplicity of tiny holes along its periphery is provided. Into this annular space is open a washing duct 280. The filter seat 276 and sprinkler nozzle 279 are connected with the funnel cylinder in such a manner that they can be superposed as intimately as possible. The funnel can be moved into and out of the container 271 by drives not shown which can move vertically and horizontally. The afore-described components constitute a filtration tank unit 513a. Another container is indicated at 282. One end of a sample pipe 277 is open in the upper part of the container, while a sample-drain pipe 283 is open in the bottom of the vessel and is also in communication with a sample-line valve 184. In addition, a manifold 285 is open in the upper part of the container 282 and is also communicated with an increased-pressure line valve 287 and a reduced-pressure line valve 286. In this way a filtrate-collecting unit 513b is constructed. The filtration unit of the filter paper type thus consists of the filtration tank unit 513a and filtratecollecting unit 513b. The filtrate-collecting unit may also serve as such for any other unit equipment.

The operation of this filtration unit will now be described. A predetermined amount of the sample is fed to the container 271 through the sample pipe 272 either under pressure through the sample-line valve 273 opened or by gravity. A sheet of commercially available filter paper having a suitable shape is attached closely to the underside of the filter seat 276 of the funnel 281 that was taken out of the container 271 prior to the filtration. The close attachment is attained, for example, by opening the reduced-pressure line valve 287 of the sampling unit 513b and maintaining a reduced (negative) pressure in the container 282 as well as in the sample pipe 277 in communication therewith. The funnel loaded with the filter paper is then slowly introduced into the container 271 and kept in a position where a necessary amount of the sample can be filtered out. The sample filtered through the filter paper is drawn up into the adjacent container 282 wherein a reduced pressure is maintained. Conveyance of this sample is effected by the active transference from the filtrate-collecting unit 513b. The used filter paper is abandoned by taking the funnel 281 out of the container and opening the increased-pressure line valve 286 thereby blowing off the filter paper from the seat. The residues of the sample deposited on the outer cylinder wall of the funnel 281 and on the inner wall of the container 271 are washed away by placing the funnel 281 into the container 271 and spraying a washing solution under pressure through the washing duct 280 and sprinkler nozzle 279. Where two or more washing solutions are used, the afore-described procedure of washing with the washing unit 511 may be adopted. In that event, the waste-liquid line valve 275 may be opened to drain off the waste liquid and washings into the waste liquid line (not shown) which is ready for suction at all times.

Next, a filtration unit of the filter board type will be explained with reference to FIG. 15. The principle of its operation is that the filtration is carried out using a stationary filter board, for example, of glass, and, after each cycle of filtration, the filter board is washed by a washing solution capable of dissolving the filtration residues, which are mostly solids, while, for example, the filtrate is flown contrariwise over the board. In the upper part of a container 291 a sample pipe 292 is open via a sample-line valve 293. A drain pipe 294, open in the lower part of the container, is also communicated with a waste-liquid line valve 295. A manifold 296, open in the upper part of the container 291, is provided with an atmospheric-pressure line valve 297, an increased-pressure line valve 298, and a reduced-pressure line valve 299. Moreover, a nozzle 300 extends downwardly from the top of the container 291 and is open at a suitable point just clear of the bottom of the container. The nozzle 300 communicates to a sample line 301, filter 303, and a tee 304 that leads to a change-over valve 305 and also to a sample-line valve 308. These components combinedly form a filtration tank unit 514a. The filter 303 has a filter board, e.g., of glass, in the center. The change-over valve 305, like the one described in relation to the washing unit, is designed to establish alternative communication between the tee 304 and either a washing-solution A line 306 or a washing-solution B line 307, or some other line. In the upper part of another container 310 is open a sample pipe 309 which also communicates to the sample-line valve 308. A sample-drain pipe 311, open in the lower part of the container, is also communicated with a sample-line valve 312. A manifold 313, open in the upper part of the container 310, communicates to an increased-pressure line valve 314 and a reduced-pressure line valve 315. Such is the construction of a filtrate-collecting unit 514b. The filtration unit of the filter board type thus comprises the filtration tank unit 514a and filtrate-collecting unit 514b.

This filtration unit operates in the manner now to be described. A predetermined amount of the sample is admitted into the container 291 through the sample pipe 292 either under pressure via the sample-line valve 293 or gravitationally. Next, the atmospheric-pressure line valve 297, sample-line valve 308, and reduced-pressure line valve 315 are opened. This establishes communication between the containers 291, 310 through the sample line and the associated fittings, thus enabling a reduced (negative) pressure to prevail in the container 310. Consequently, the sample from the container 291 is drawn up by suction through the nozzle 300 and sample line 301 into the filter 303, where the solid contents are removed and the filtrate alone is admitted into the container 310 by way of the tee 304, sample-line valve 308, and sample pipe 309. After a necessary amount of the sample has been filtered, all the valves are closed. When the filtrate in the container 310 is to be transferred to some other place, the increased-pressure line valve 314 and sample-line valve 312 are opened to effect the transference. Solids and other residues deposited on the walls of the filter 303 and filter board 302 are washed away with the washing solution A under pressure that can dissolve those residues, through communication between the washing-solution A line 306 and tee 304. At this time it is only necessary in the filtration tank unit to open the atmospheric-pressure line valve 297 or, alternatively, the waste-liquid line valve is opened to drain off the washings into the waste-liquid line wherein suction is provided at all times. If the washing solution of one type alone is found inadequate for the washing purpose, the change-over valve 305 may be manipulated for communication with the line 307 for supplying the washing solution B under pressure. Desirably, after the necessary amounts of such washing solutions have flowed down, the change-over valve 305 is turned to introduce a jet of air (or other inert gas) under pressure through the tee 304, filter 303, sample line 301, and nozzle 300, thereby to clean the inner walls of those lines. In order to wash the containers 291, 310, it is generally desirable to apply the method of washing with the washing unit that has already been described.

It should be obvious to one skilled in the art that the filter incorporated in this filtration unit may use, if necessary, a dialyzing membrane in place of the ordinary filter board so that it can serve as an ultrafilter.

The seventh example is an extraction unit as schematically illustrated in FIGS. 16 and 17. The technical concept of the extraction resides in mixing with agitation a sample and an extracting solvent in an agitation tank, thereby extracting the objective (extractive) ingredients from the sample, transferring the extracts into a settler (stationary separation tank) and keeping them stationary for a certain period of time to separate them gravitationally into light and heavy layers, and then taking out the light or heavy layer under an increased or reduced pressure. FIG. 16 is a schematic arrangement for taking out a light layer, and FIG. 17 for taking out a heavy layer. The former arrangement will now be detailed first. In the upper part of a container 321 is open a sample pipe 322 that extends via a sample-line valve 323. A sample-drain pipe 324, open in the bottom of the container, is in turn communicated with a sample-line valve 325 and a waste-liquid line valve 330. A manifold 326, open in the upper part of the container, is equipped at the other part with an atmospheric-pressure line valve 327, an increased-pressure line valve 328, and a reduced-pressure line valve 329. A reagent inlet pipe 331 opens in the upper part of the container and is connected, at the other end, with a change-over valve 332 that can alternatively communicate the pipe 331 with a washing-solution A line 333 or a washing-solution B line 334 for selective supply of the washing solutions under pressure. Inside the container 321 there is placed an agitator blade 335 for agitating the sample therein, and, outside the vessel there is a drive, e.g., a magnetic stirrer 336, for driving the blade 335. These components constitute an agitation unit 515. It should be construed possible, though not shown, that the change-over valve 332 can be stopped in a position where it does not establish any connection between the pipe 331 and either washing-solution line, or where the valve itself is closed. Another container 337 is so shaped as to comprise an upper part or a light-layer compartment E that has a suitable contour and a suitable capacity, a lower part or a heavy-layer compartment G also having a suitable contour and a suitable capacity, and an intermediate compartment F having the same or smaller diameter than those of the other compartments. The expression "suitable contour" as used herein means a contour suited for the transference of the sample or the like to be described later and also suited for washing of the container to be described later. In the upper part of the container 337 enters one end of a sample pipe 338 that communicates at the other end to the above-mentioned sample-line valve 325. A sample-drain pipe 339, open in the lower part of the container, is associated at the other end with a sample-line valve 340 and a waste-liquid line valve 352. A manifold 341 that opens in the top of the container 337 is in communication with an atmospheric-pressure line valve 342, an increased-pressure line valve 343, and a reduced-pressure line valve 344. A light-layer-conveying valve 346 is installed on a nozzle 345 which, in turn, extends into the upper part of the container 337. Also open in the upper part of the vessel is a pipe 348 equipped with a change-over valve 349 for its selective communication with washing-solution lines 350, 351 in the same manner as has been described with the agitation unit 515. In the manner described a settler unit 516 is built. The lower end of the sample pipe 338 is preferably open in the center of the intermediate compartment F of the container 337, while the nozzle 345 is preferably open in the lower part of the light-layer compartment E. Thus, the agitation unit 515 and settler unit 516 are combined to form an extraction unit for the removal of the light layer.

The operation of this extraction unit will now be explained. It is assumed that the sample to be handled amounts to 100 ml and the extractive ingredients contained therein are to be extracted with 10 ml of an extracting solvent lighter in specific gravity than the sample. Here a "suitable capacity" for the heavy-layer compartment G is such that the sum of the capacity of the compartment G and one half of the capacity of the intermediate compartment F amounts to 100 ml. Stated differently, 100 ml of the sample to constitute the heavy layer, when placed in the container 337, forms a liquid level in the vicinity of the open end of the sample pipe 338. A "suitable capacity" for the light-layer compartment E is such that when a light layer overlies the heavy layer its liquid level reaches approximately the center height of the light-layer compartment E (the volume being about 20 cm.sup.3 in this embodiment).

First, the sample-line valve 323 and reduced-pressure line valve 329 are opened to convey the sample into the container 321 through the sample pipe 322. The extracting solvent may be premixed with the sample or may be separately introduced into the container by means not shown but already explained in relation to the reagent-addition unit. After the sample and extracting solvent have been fed to the container 321, all of the valves may be closed or, if necessary, the atmospheric-pressure line valve 327 is opened and the charge is mixed with agitation by the agitator blade 335 driven, for example, by the magnetic stirrer 336. The container 327 and agitator blade 335 are, of course, so shaped as to suit extraction. Following the agitation for a sufficient period for extraction, the agitation is discontinued, the atmospheric-pressure line valve 327 is closed, and the increased-pressure line valve 328, sample-line valve 327, and atmospheric-pressure line valve 342 are opened. By this procedure of active transference from the agitation unit 515 the sample-solvent mixture is conveyed to the container 337. Because an extracting solvent is often volatile, the passive transference from the agitation unit 515 is not advisable. Following the transference of the sample-solvent mixture to the settler unit 516, all valves are reclosed and quiescense is maintained for a sufficient period to effect the separation of the liquid into heavy and light layers. The light layer so separated is taken out by opening the light-layer-conveying valve 346 and increased-pressure line valve 343 and forcing the layer out through the nozzle 345 open in the lower part of the light-layer compartment E. At this time, care must be exerted to use a pressure (positive pressure) source that will not disturb the boundary between the light and heavy layers. If the heavy layer of the sample-solvent mixture left behind is to be examined by a subsequent chemical analysis, only the increased-pressure line valve 343 and sample-line valve 340 are opened to take out the heavy layer from the container 337. The portion of the residual sample-solvent mixture close to the inter-layer boundary must be left intact for subsequent abandonment through the waste-liquid line valve 352. Washing of the interior of the container 321 is carried out in the same manner as described in connection with the washing unit 511. It may be accompanied by agitation by the blade 335. The inside of the container 337 may be washed again by the same procedure as with the washing unit 511.

As regards the extraction unit for selectively taking out a heavy layer, it is noted that the agitation unit to be employed is the same as the one for the removal of the light layer and, therefore, the settler unit alone will now be explained in detail by reference to FIG. 17. A container is indicated at 361. A nozzle 362 is sealed in the lower part of the container and is open at a point therein to be described later. At its lower end the nozzle is connected to a sample-line valve 363 and a sample line not shown (corresponding to the sample line 338 of FIG. 16 if this settler unit is to be communicated to the agitation unit). A sample-drain pipe 364 is open in the lower part of the container 361 and has, at the other end, a sample-line valve 365 and a waste-liquid line valve 370. In communication with a manifold 366 which opens in the upper part of the container, there are installed an atmospheric-pressure line valve 367, an increased-pressure line valve 368, and a reduced-pressure line valve 369. Also provided are a washing-solution C line 373, a washing-solution D line 374, a change-over valve 372 for the respective lines, and a reagent inlet pipe 371 communicated with those lines and change-over valve and is open in the upper part of the container. These components are assembled to form a settler unit 517 for taking out a heavy layer. The shape of the container 361 is suited for washing. It is desirable that, when the volume of the sample to be treated is 100 ml and that of the extracting solvent is 20 ml, the capacity of the heavy-layer compartment J in the lower part of the container 361 is slightly less than 20 cm.sup.3, say 18 cm.sup.3, while the capacity of the upper light-layer compartment H of the container 361 is about 120 cm.sup.3. The open end of the nozzle preferably is held near the boundary between the heavy and light layers, or, in this embodiment, at a point corresponding to the surface level of the liquid in an amount of 20 cm.sup.3 filled in the lower part of the container 361.

The settler unit 517 is operated for selective removal of a heavy layer therefrom in the following way.

The sample-solvent mixture agitated by the agitation unit 515 is conveyed to the container 361 through the nozzle 362 by the active transference from the unit 515. The sample mixture separated into heavy and light layers before the transference is taken out from the lower part of the container of the agitation unit, and initially the heavy layer is conveyed and, immediately after the liquid level of the layer has reached the open end of the nozzle 362, the conveyance of the light layer is started. Consequently there is no possibility of the layers being disturbed by the flow of the sample mixture in the settler. The liquid is allowed to stand for a period of time enough to effect its thorough separation into the heavy and light layers. Then, if the heavy layer alone is to be taken out, the sample-line valve 365 and increased-pressure line valve 368 are opened. Care must be used to discontinue the transference leaving a part of the heavy layer behind. If, immediately after this, the light layer is to be taken out for chemical analysis, it is possible to open the waste-liquid line valve 370 and increased-pressure line valve 368 to abondon the residual heavy layer and a lower portion of the light layer, and thereafter open the sample-line valve 365 and increased-pressure line valve 368 to take out the rest. Washing of the interior of the container 361 may be performed generally in conformity with the procedure described in connection with the washing unit 511.

The eighth example of unit equipments is an incubator unit as schematically illustrated in FIG. 18. Since the rate of a chemical reaction generally depends upon the temperature, it is required to maintain a constant ambient temperature for the reaction vessel. The method employed in this embodiment is, for example, to circulate a thermal medium such as water at a constant temperature around the reaction vessel. A container is indicated at 381. A sample pipe 382 provided with a sample-line valve 383 is open in the upper part of the container. A sample-drain pipe 384 which opens in the lower part of the vessel is equipped with a sample-line valve 385 and waste-liquid line valve 390. A manifold 386 also connected to the upper part of the container is communicated with an atmospheric-pressure line valve 387, an increased-pressure line valve 388, and a reduced-pressure line valve 389. All around the container except for its top wall, a jacket 391 is provided in the form of an enclosed vessel open only at a constant-temperature water inlet K and a constant-temperature water outlet L, and through which the sample-drain pipe 384 extends from the container downward. These components form an incubator unit 518.

The function of this incubator unit will now be explained. First, a thermal medium such as, for example, water at a given temperature is led into the jacket through the constant-temperature water inlet K and is overflown out of the outlet L, so that the temperature of the container 381 can be kept constant at a preset level. A sample is fed into the container 381 by the active transference into the incubator unit by use of the sample-line valve 383 and reduced-pressure line valve 389. After the sampling, the atmospheric-pressure line valve 387 is opened to maintain the sample at the atmospheric pressure. If necessary, the sample is agitated while the atmospheric-pressure line valve is kept open and, where necessary, by means of an agitator such as a magnetic stirrer. In the manner described, the sample will attain the preset temperature. It is then retained in the container for a period of time necessary for the chemical reaction desired. Thereafter, the sample-line valve 385 and increased-pressure line valve 388 are opened, and the sample is transfererd to some other place by the active transference from the incubator unit 518. While water is used in this embodiment as a thermal medium for keeping the temperature constant, it is possible, of course, to replace the thermal medium by an electric heater.

The ninth exemplary unit equipment is an aeration unit schematically shown in FIG. 19. There is shown a container 401, in the upper part of which is open a sample pipe 402 equipped with a sample-line valve 403. A sample-drain pipe 404 is open in the bottom of the container 401 and is equipped with a sample-line valve 405. A manifold 406 opens in the upper part of the container and is communicated with an increased-pressure line valve 407 and a reduced-pressure line valve 408. Also open in the upper part of the container is a gas-collecting pipe 409 which, in turn, communicates to a trap 410 and a gas-collecting valve 411. From above the container 401 comes down an aerating pipe 413, which terminates with a nozzle 414 at the lower end. The other end of the aerating pipe 413 is provided with an aerating valve 412. Constructed in this way is an aeration unit 519.

The operation of this aeration unit 519 will be described in detail below. Because the sample to be handled often contains volatile matter, it is desirable that the sample be kept under pressure and that it be transferred by the passive function of the aeration unit 519 with both the sample-line valve 403 and atmospheric-pressure line valve 407 opened. Next, the gas-collecting valve 411 connected to a gas-collecting container not shown is opened, while the aerating valve 412 is opened to admit an aerating gas under pressure into the sample. The nozzle 414 has a shape suited for the aeration purpose; for example, it may take the form of a perforated disc, ball or tube, or a finely perforated pipe directed against the inner wall of the container 401. Since the gas after the aeration (which has taken over the volatile matter from the sample) contains fine particles of the liquid, the trap 410 for gas-liquid separation is provided on the gas-collecting pipe 409, preferably close to the container 401. The aerated sample is conveyed elsewhere by the active transference from the aeration unit 519, with the sample-line valve 405 and increased pressure line valve 408 opened.

The tenth example of unit equipments is a thermal concentration unit as schematically shown in FIG. 20, which will now be described in detail. In the upper part of reaction tank 421 is open a sample pipe 422, which in turn communicates to a sample-line valve 423. In the lower part of the tank is open a sample-drain pipe 424 which is connected to a sample-line valve 425 and a waste-liquid line valve 430. A manifold 426, also open in the upper part of the tank, is provided with an atmospheric-pressure line valve 427, increased-pressure line valve 428, and a reduced-pressure line valve 429. A vapor pipe 431 in communication with the upper center of the reaction tank 421 is partially covered with a cooling jacket 432, which in turn has a cooling-water inlet 433 and a cooling-water outlet 434. Near the upper end of the jacket, a vapor valve 435 is installed. A capillary tube 436 extends from above the reaction tank 421 downward and is open in the lower part of the vessel, whereas the upper end of the tube 436 is connected to a line 438 via a valve 437. An oil bath 444 to be described later surrounds the reaction tank 421 except for its top portion, the sample-drain pipe 424 extending downward through the bath. In this way a thermal concentration unit 520 is constructed. A jacket 439 containing the oil bath is provided with a reflux tube 441 in the upper part which is integrally formed with an air condenser 442 and an open port 443. An electric heater 440 is liquidtightly sealed in the lower part of the bath. The jacket 439 is filled with a type of oil (not shown) having a high boiling point and a low vapor pressure.

The operational function of this unit is as follows. The oil in the jacket 439 is heated by the electric heater 440 and is partly evaporated. The oil vapor is cooled by the air condenser 442 (which may be replaced by a water condenser, if necessary), and is returned to the bath through the reflux tube 441. The open port 443 permits the jacket 439 to maintain the prevailing atmospheric pressure inside. The oil temperature can be kept at a predetermined level by controlling the power supply to the electric heater 440.

Now it is assumed that the sample-line valve 423 has been turned open, the sample fed to the reaction tank 421, and the vapor valve 425 opened. The oil bath 444 preheated to a suitable temperature is further heated to a predetermined temperature by the electric heater 440. If the sample is to be heated up to its boiling point, it is a desirable practice to introduce clean air or inert gas under slight pressure into the line 438 and open the valve 437, so that the gas is gradually blown out of the capillary tube at a rate low enough to avoid bumping. The cooling jacket 432 provided on the intermediate part of the vapor pipe 431 is designed to condense high-boiling-point ingredients of the sample and return the condensate to the container. For this purpose cooling water is admitted into the jacket through the inlet 433 and is overflown through the outlet 434. If low-boiling-point ingredients are to be recovered, a recovery tank (not shown) may be located on the other end of the vapor valve 435. If the unit is intended for mere heating, a cooling jacket having a suitably chosen length may be used to reflux every drop of the condensate. After the thermal concentration to a predetermined value, the heating is discontinued. The valve 437 and vapor valve 435 are closed, while the sample-line valve 425 and atmospheric-pressure line valve 427 or increased-pressure line valve 428 are manipulated to effect transference, either passively or actively, of the concentrated matter elsewhere from the thermal concentration unit 520.

The eleventh example is a distillation unit. FIG. 21 is a schematic view of the arrangement. This unit consists of three major components, i.e., a heating tank, a cooling jacket, and a distillate tank. The heating tank is analogous to the thermal concentration unit just described above. The tank 451 is connected at its upper part to a sample pipe 452 for the supply of the sample through a sample-line valve 453. In the lower part of the tank is open a sample-drain pipe 454, which in turn is connected to a waste-liquid-line valve 459. A manifold 455 opens, too, in the upper part of the heating tank and is provided, on the other hand, with an atmospheric-pressure line valve 456, an increased-pressure line valve 457, and a reduced-pressure line valve 458. The heating tank 451 is further connected to a vapor pipe 466 through its top wall. An oil bath 465 to be described later surrounds the heating tank 451 except for its top portion, the sample-drain pipe 454 extending downward through the bath. These components form a heating tank unit 467. The oil bath 465 comprises: a jacket 460 which surrounds the heating tank 451 except for the top portion and allows the sample-drain pipe 454 to penetrate therethrough; a reflux tube 461 which opens in the upper part of the jacket and is formed with an air condenser 462 and terminates at its upper end with a port 463 open in the atmosphere; an electric heater 464 sealed in the bath on the bottom of the jacket 460; and a chemically stable oil or heat medium having a high boiling point and a low vapor pressure filled in the jacket 460. The cooler 471 comprises a cooling jacket 468 having a cooling water inlet 469 and an outlet 470, which jacket is connected at one end to the vapor pipe 466 and at the other end to a check valve 472 that contains a float 473. The distillate tank unit 483 comprises: a receiving tank 474 in which a nozzle 482 connected to the check valve 472 extends downward; a sample-drain pipe 477 which opens in the lower part of the receiving tank 474 and is connected to a sample-line valve 478; a manifold 479 which opens in the upper part of the tank and is provided with an atmospheric-pressure line valve 480 and an increased-pressure line valve 481; and a reagent inlet pipe 475 which opens in the upper part of the tank 474 and is communicated with a reagent inlet valve 476. The heating tank unit 467, cooler 471, and distillate tank unit 483 are combined to form the distillation unit.

The operational function of this distillation unit will now be explained. The oil in the jacket is heated by the electric heater 464 and is partly evaporated. The oil vapor is cooled by the air condenser 462 (or, if necessary, by a water condenser) and is returned to the jacket through the reflux tube 461. The open port 463 permits the maintenance of atmospheric pressure in the jacket 460, and control of the power supply to the electric heater 464 makes it possible to keep the oil temperature at a predetermined level. The check valve 472 works in such a manner that, if there is no liquid therein, it does not function as a valve, but if there is, the float 473 rises to close the path for an upward flow but provide no obstruction to a downward flow. It follows that, when the check valve 472 is not filled with a liquid (or when all other valves of the distillation unit are closed), the heating tank 451 and receiving tank 474 are in communication with each other through the cooler 471, thus forming a closed system independent of the outside. The sample to be distilled may be fed to the heating tank 451 in four different ways. One (A) is by passive transference to the distillation unit with both the sample-line valve 453 and the atmospheric-pressure line valve 456 opened. Another (B) is by passive transference to the distillation unit with the sample-line valve 453 and atmospheric-pressure line valve 480 opened. The third procedure (C) is to open the sample-line valve 453 and reduced-pressure line valve 458 and effect active transference to the distillation unit. The fourth (D) is by opening the sample-line valve 453 and a reduced-pressure line valve not shown which is communicated with the manifold 479 and thereby effecting active transference to the distillation unit. One of these procedures may be chosen in consideration of the unit's combination with another unit or units intended.

With power supply to the electric heater 464, the oil bath preheated to a suitable temperature is further heated to a desired temperature, and distillation is started. At this time the atmospheric-pressure line valve 480 must be kept open. If bumping of the sample is to be prevented, the method as used with the thermal concentration unit should be adopted, too. The vapor of the sample is condensed by the cooler 471, dropped through the nozzle 482, and is collected in the receiving tank 474. If it is desired to stabilize the distilled sample by having the same absorbed by an absorbent, the absorbent is supplied beforehand to the tank 474 through the reagent inlet valve 476. Judicious choice of the open end position of the nozzle relative to the reagent level is an important consideration. This may necessitate a modification to the bottom contour of the receiving tank. Should the open nozzle end be immersed in the distilled sample during the distillation, the heating container would form a closed system. In such case a pressure change may lead to a backward flow of the distilled sample from the nozzle 482 up to the cooler 471. When this happens, the float 473 rises up and forms a check valve that keeps the distilled sample from flowing back to the cooler 471, in the manner already explained. After distillation for a predetermined period of time, or after a predetermined amount of distillate has been obtained (as determined by the liquid level detection methods with the dilution unit, although no such means is shown here), the electric heater 464 is switched off, the atmospheric-pressure line valve 456 (or, if necessary, the increased-pressure line valve 457) is opened and, after the pressure inside the system has returned to the atmospheric level, all valves are closed. The atmospheric-pressure line valve 456 may have to be kept open depending on the condition of the oil bath 465. Residues from the heating tank are drained off by opening the waste-liquid line valve 459, and the sample in the distillate tank unit 483 is transferred elsewhere by opening the sample-line valve 478. Washing of the heating tank 451 and receiving tank 474 may be carried out in the manner already described in connection with the washing unit. If the cooler has to be cleaned, it may be either washed with the washing solution distilled in the way above described or cleaned with a jet of air or inert gas.

So far a total of eleven typical unit equipments having separate functions for chemical operations have been described in detail. As noted in the early paragraphs dealing with the fundamental principle of the invention, these units may be freely combined to meet the particular requirements for various chemical analyses and, in that way, fully automatized analytical operations will be made possible.

As a preferred embodiment of the present invention, an automatic analyzer built in conformity with the invention for conducting Testing Method B (indophenol test) for the analysis of ammonium ions according to JIS K-102 will now be described.

The indophenol test will be briefly explained first. One hundred milliliters of test water (usually adjusted to about pH 2 by the addition of hydrochloric acid for the preservation purpose) is neutralized to about pH 7 by dropping a sodium hydroxide solution. With the addition of one milliliter of a zinc sulfate solution, the mixed solution is thoroughly mixed with stirring. The pH is adjusted to about 10.5 by the addition of a mixed solution of sodium hydroxide and sodium carbonate (usually in an amount of 0.3 to 0.5 ml). The mixture is again throughly mixed with stirring, allowed to stand for some time, and the supernatant fluid is separated or filtered out to obtain a clear solution. A suitable amount of this test water is neutralized to about pH 7 with hydrochloric acid, and water is added to give a total amount of about 10 ml. One milliliter of an EDTA (disodium ethylene diamine tetraacetate) solution and 4 ml of a sodium phenolate solution are added and the mixture is shaken well. Finally 3 ml of a sodium hypochlorite solution and water are added to obtain a total amount of 25 ml, and the mixture is mixed with shaking. The mixture is allowed to stand at 20.degree.-25.degree.C for about 20 minutes. After the standing, it is transferred to a 10 mm absorption cell of a spectrophotometer, and the absorbance is determined in the vicinity of the wave-length of 625 nm, and the amount of ammonium ions is found from a calibration curve prepared beforehand.

FIG. 22 is a schematic diagram of this automatic ammonium ion analyzer embodying the present invention. The component units will now be detailed. Reference numeral 601 indicates a fixed-quantity sampling unit, the construction and function of which have already been described separately. The unit is equipped with a metering nozzle 602 and outgoing and incoming sample-line valves 603 and 671. A reagent-addition unit 611 is associated with a pH-adjusting unit. The structures and operational functions of these units have already been clarified. A sample line 612 extends between the sample-line valve 603 and the upper part of the container for the reagent-addition unit 611. A pH electrode 613 is operatively connected to an automatic titrator located outside but not shown, so that the reagent can be dropped from a sodium hydroxide solution line for the pH adjustment of the sample. The reagent-addition unit is also equipped with a magnetic stirrer 614 and a sample line 615. Settler tank units 621, 621' are constructed and designed for functioning as have been explained in the early paragraphs dealing with the fixed-quantity sampling unit. In the upper parts of these settler tanks are open, respectively, sample lines 623, 623' which in turn communicates to the sample line 615 via sample-line valves 622, 622'. Nozzles 624, 624' which extend through the top walls of the settler tanks and open near the bottoms of those tanks are provided with sample-line valves 625, 625' above the tanks. The settler tanks 621, 621' are arranged in parallel with the reagent-addition unit 611 and a filtration unit 631 now to be described. The filtration unit, the construction and function of which have already been detailed separately, has a sample line 632 open in the vessel and also in communication with the above-mentioned sample-line valves 625, 625'. The unit is equipped, moreover, with a vertically and horizontally movable funnel 633 and a sample line 634 communicated with the funnel. A fixed-quantity collecting unit 641, which in effect serves as a filtrate-collecting unit for the filtration unit 631, has the structure and function of the fixed-quantity sampling unit already described as a unit equipment. A sample line 634 provided with a sample-line valve 635 is open in the upper part of the vessel of this unit. In addition, a nozzle 643 and a sample-line valve 642 are installed. A reagent-addition unit 651 is associated with a pH-adjusting unit. In this unit 651 is open a sample line 652 in communication with the sample-line valve 642. The unit is also equipped with a pH electrode 653, a magnetic stirrer 654, etc. An incubator unit 661 is built and functions in the manner described separately as a unit equipment. It is communicated to the reagent-addition unit 651 with a sample line 663 open in the bottom of that unit and extended to this unit 661 via a sample-line valve 662. On the other hand, the unit 661 is communicated to a sample line 672 through a sample-line valve 664. Although two such incubator units are shown, actually five units are connected in parallel with the reagent-addition unit 651 and sample line 672. An atmospheric-pressure line 681, an increased-pressure line 682, a reduced-pressure line 683, and a waste-liquid line 686 in which suction is provided at all times are all connected to the above-mentioned units through valves, as illustrated. The functions of those valves have already been explained in connection with the individual unit equipments. The atmospheric-pressure and increased-pressure lines are in communication with reservoirs of clean air or inert gas free of impurities such as carbonic acid gas. Also provided are a zinc sulfate solution line 692, an alkaline mixed solution line 693, a hydrochloric acid line 694, an EDTA solution line 695, a sodium phenolate solution line 696, and a sodium hypochlorite solution line 697, through which predetermined amounts of a zinc sulfate solution, mixed solution of sodium hydroxide and sodium carbonate, aqueous solution of hydrochloric acid, EDTA solution, sodium phenolate solution, and sodium hypochlorite solution can be forced into the system. The forced introduction of these solutions may be accomplished, for example, by a combination of an injector and a valve motion which can be automatically operated, or a commercially available reagent-pipetting device.

The operation of this ammonium ion analyzer will be described below in the order of the procedural steps involved. It is to be understood that all of the surface to contact the sample and other liquids to be handled are made of chemically resistant material, e.g., glass, fluorocarbon resin, polyvinyl chloride or the like, and that, unless otherwise specified, all valves are normally closed. The sample line (not shown) in communication with the sample-line valve 671 is immersed in water to be tested, and the sample-line valve 671 and a suction valve communicated to the nozzle 602 is opened, so that the test water is sampled by the active transference to the fixed-quantity sampling unit 601. At this time the open end position of the nozzle 602 should be equal to the liquid level of 100 ml of the sample in the vessel. After the sampling, the sample line immersed in the test water is taken out and the sample deposited on the inner wall of the sample line and the associated parts is blown away cleanly with a jet of air. The sample portion overflown from the nozzle is drained into the waste-liquid line wherein the suction prevails. The atmospheric-pressure line valve is opened and the pressure inside the tank is made atmospheric. Next, the increased-pressure line valve and sample-line valve 603 of the fixed-quantity sampling unit 601, and the atmospheric-pressure line valve of the reagent-addition unit 611 are opened to convey the sample by active transference from the fixed-quantity sampling unit 601 to the reagent-addition unit 611. After the transference the interior of the sample line 612 is cleaned with a jet of air. As already noted in connection with the pH-adjusting unit, a reaction unit equipped with a pH electrode must at all times be kept at the atmospheric pressure. The 100 ml portion of the test water fed to the reagent-addition unit is adjusted to pH 7 by the addition of a sodium hydroxide solution supplied from the line 691 by means of an automatic titrator cooperative with the pH electrode 613, while the sample is being agitated, for example, by the magnetic stirrer 614. Next, one milliliter of a zinc sulfate solution and 0.5 ml of a sodium hydroxide-sodium carbonate solution are added, respectively, from the zinc sulfate solution line 692 and alkaline mixed solution line 693. Desirably the sample is continuously agitated during this course of addition. Then, a white precipitate will result. Manipulation for the opening and closing of the solenoid valves for the above operation is performed by a programmer that produces a working program of the control sequence with the aid of electric pulse generators which give 3-, 8- and 16-second pulses at intervals of 30 seconds or thereabouts. All of the foregoing steps of chemical operation and the washing to be described later are carried out in a period of five minutes. The sample that has yielded the white precipitate is conveyed to the settler tank unit 621 by the active transference with the sample-line valve 622 and reduced-pressure line valve opened. In about 7 minutes the precipitate aggregates to form sufficiently coarse particles to settle down on the bottom of the tank, and the liquid portion becomes almost clear in the portion of the settler tank unit where the lower end of the nozzle 624 opens. In the meantime, the fixed-quantity sampling unit 601 and reagent-addition unit 611 are thoroughly washed by the method of the washing in the washing unit 511 already described and by means of a washing nozzle or the like not shown, using a dilute acid and pure water. Following the washing, untreated test water is again sampled and chemically treated in the manner above described. Then, the sample-line valve 622' and reduced-pressure line valve are opened and the treated sample is transferred to the settler tank unit 621'. After the lapse of a predetermined period of time, the increased-pressure line valve and sample-line valve 625 are opened and only the supernatant fluid of the sample in the settler tank unit 621 is forced by the active transference therefrom to the adjacent filtration unit 631 through the nozzle 624. The sample residues containing the white precipitate are abandoned into the waste-liquid line 686 through the waste-liquid line valve and atmospheric-pressure line valves both opened for the draining purpose. The emptied vessel is washed with a solution from a washing nozzle not shown. Since this step requires about 10 minutes, the pair of settler tank units 621, 621' are connected in parallel. The sample fed to the filtration unit 631 still contains fine particles of the precipitate. A sheet of filter paper cut to a suitable size and shape is applied to the funnel 633 taken out in advance from the vessel, and the valve communicated to the nozzle 643 of the fixed-quantity collecting unit and the sample-line valve 635 are opened so that the filter paper can be sucked up by the funnel, and then the funnel is lowered and immersed into the sample to admit the sample into the fixed-quantity collecting unit 641 through the funnel and the sample line 634. The open end of the nozzle 643 is preadjusted to the position equivalent to the liquid level that 10 ml of the sample produces. Next, the sample-line valve 642 and the increased-pressure line valve of the fixed-quantity collecting unit are opened to force the sample into the adjacent tank of the reagent-addition unit. The used filter paper of the filtration unit is abandoned, and the unit is washed, together with the fixed-quantity collecting unit, by means of washing nozzles not shown. The combined period of time required for these two steps is about 5 minutes. Inside the reagent-addition unit 651, the sample is adjusted to pH 7 by the addition of an aqueous solution of hydrochloric acid from the line 694 and with the use of the pH electrode 653, while being agitated by the magnetic stirrer 654 in the manner described in relation to the reagent-addition unit 611. Next, 1 ml of an EDTA solution, 4 ml of sodium phenolate solution, and 3 ml of sodium hypochlorite are added, respectively, from the lines 695, 696, 697. The mixture is thoroughly agitated and is diluted with pure water to a total volume of 25 ml in a dilution unit of the electric conductivity type, which is not shown but has already been described as a unit equipment. The sample is transferred actively to the incubator unit 661 by use of the sample-line valve 662 and reduced-pressure line valve. The reagent-addition unit 651 is subsequently washed. The above step requires about 5 minutes. The sample in the incubator unit 661 is kept at 25.degree.C by water at that temperature circulated through the jacket. Because the time required for this step of color development and stabilization is about 20 minutes, and also because the ensuing samples arrive at this station at intervals of 5 minutes, five such incubator units are connected in parallel and the samples are temporarily stored in succession in these units. This means that, when the fifth incubator unit is supplied with a sample, the sample in the first unit 661 has been kept at 25.degree.C for about 20 minutes and the color developed has stabilized. Therefore, the increased-pressure line valve and sample-line valve 664 are opened, and the sample is conveyed through the sample line 672 to the flow cell in the visible range of a spectrophotometer not shown, so that its absorbance is determined. After each sample has been transferred in this way, the sample line 672 and flow cell are cleaned with a jet of air. The time required for the above-described step is 5 minutes. From the foregoing it follows that the results of analysis of the first water sample by this automatic analyzer are made known about 45 minutes after its introduction into the apparatus, and thenceforth the results of the following samples are revealed at intervals of 5 minutes. The results are subjected to data processing by an electronic apparatus on the basis of calibration curves obtained in advance from tests on controls, and are converted into ratios by weight of ammonia contents or the like, and then are recorded together with the sample numbers and other information. In a typical test with this analyzer, the following results were obtained. The calibration curve attained linearity with 0-3 ppm, the reproducibility was three percent in terms of the Cv value, the sensitivity was one percent of the full scale, and the degree of contamination was three percent. These values indicate that the apparatus is of great value as a fully automatic analyzer.

While the programmer for the sequential procedure of opening and closing solenoid valves is of the electronic type in this embodiment, genuine fluid elements may be employed instead. In the latter case pneumatically driven valves are advantageously used in place of the solenoid valves.

In addition to those embodiments of the invention so far described, a few other embodiments as unit equipments will now be illustrated. One of them concerns the method of agitation with an agitation unit for an extracting operation. The agitation is accomplished not merely by the use of remote force as by the magnetic stirrer shown in FIG. 16, but equally by mechanical means as in FIG. 23. The latter comprises a glass vessel 701 having a neck 702 on its top, a shaft 703 of glass, fluorine-contained resin or other chemically stable material which fits in the neck to form a labyrinth seal, a bladed rotor 704 of glass or other chemically stable member supported at the lower end of the shaft 703 and located in a suitable part of the vessel, and a motor 705 for driving the shaft and rotor at a suitable speed. Although not shown, valves for the transport of samples are, of course, installed on the vessel. Of those valves, an increased-pressure line valve 706 may be partly opened to supply at all times a very small amount of gas under pressure to the vessel in order to avoid seizing of the labyrinth seal.

Another method pertains to heating, and an arrangement for heating in accordance with the present invention is shown in FIGS. 24a and 24b which are, respectively, a vertical sectional view and a transverse sectional view as seen in the direction of arrows in the former figure. As compared with the heating means in the embodiment described earlier which use an oil bath, this arrangement is designed to hold an electric heater in the vessel. A vessel 711, equipped with sample lines and valves not shown, is formed with a ring 713 having a circular cross section and supported near the bottom of the vessel by a connecting part 714 for integral connection with the surrounding wall of the vessel. An electric heating wire is inserted into the ring through holes 713 communicating the circular space and the outside.

With regard to valves, those to be used for contact with liquids (corresponding to the sample-line valves already described) are pinch valves, small switching valves, and change-over valves. In addition, check valves may be employed for other embodiments. With the sample-conveying system using check valves, it is not always possible to adopt both the active and passive transference procedures as with the units so far described. Nevertheless, the limitation that only one of the two procedures have to be resorted to is offset by the advantage of simplified construction of the valves.

Among possible combinations of unit equipments according to this invention are, in addition to the ammonia analyzer described above, metal analyzers equipped with extractors, cyanide monitors incorporating heating and distilling means, and various other automatic analyzers perfected by automatizing analytical operations which have hitherto been done manually.

As has been described hereinbefore, the present invention offers the following advantages:

1. Where a number of samples are to be chemically analyzed in the usual manner, the volume of each sample that can be handled is limited to at most about 10 milliliters. Under the invention, by contrast, many samples can be handled in much larger unit volumes, say between 25 and 200 ml.

2. Means for various operations involved in chemical analyses, e.g., filtration, aeration, thermal distillation, thermal concentration, addition of reagent, agitation, pH adjustment, extraction, centrifugal separation, and dissolution, can be selectively incorporated in any part of a series of analytical means of an automatic analyzer. Moreover, sampling, pretreatment of samples, analysis and recording on instruments can be automatically controlled.

3. Of the chemical operations, those which usually take long periods of time, e.g., thermal distillation and thermostatic control, are performed efficiently with increased capacities because a plurality of treating units may be arranged in parallel with the rest of unit equipments.

4. Since mutual interference of analytical steps is eliminated and the units for the chemical analysis are designed for independent operations, the overall analytical procedure may be readily modified with ease.

Claims

What is claimed is:

1. An apparatus for successively transferring a plurality of different liquid samples to a plurality of different treatment stations in an analytical system comprising:

a first treatment unit including a first enclosed vessel, a sample inlet connected to an upper part of said first vessel and a first valve connected to said sample inlet;

a second treatment unit including a second enclosed vessel, a sample outlet connected to the lowermost portion of said second vessel and a second valve connected to said sample outlet;

first conduit means fluidly communicating the lowermost portion of said first vessel with an upper portion of said second vessel;

a third valve connected to said first conduit means;

sources of gasses at an increased pressure, reduced pressure and atmospheric pressure fluidly communicating with upper portions of said first and second vessesl through respective valves; and

control means for controlling the gas sources so that a pressure differential is maintained between the interiors of said first vessel and said second vessel for transferring a sample in said first vessel to said second vessel, said control means maintaining a pressure differential between the interiors of said first vessel and said second vessel after all of the sample is transferred from said first vessel to said second vessel so that sample deposited on the walls of said conduit means is blown away cleanly by a jet of gas, said control means thereafter causing another sample to be introduced into said first treatment station.

2. The apparatus of claim 1, further comprising a third treatment unit including a third enclosed vessel; second conduit means fluidly communicating the lowermost portion of said first vessel with an upper portion of said third vessel; a fourth valve connected to said second conduit means; a sample outlet connected to the lowermost portion of said third vessel; a fifth valve connected to said sample outlet; said source of gas under pressure fluidly communicating with an upper portion of said first vessel through a valve.

3. A method for successively transferring a plurality of liquid samples to a plurality of different treatment stations in an analytical system, each treatment station including a hermetically sealed vessel, inlet means located in the upper portion of the vessel and outlet means located in the lowermost portion of the vessel, said method comprising transferring a first liquid sample to a first treatment station, establishing by means of a conduit a fluid communication between the outlet means of said first treatment station and the inlet means of a second treatment station, establishing a pressure differential between the vessel interiors of the first and second treatment stations so that said first sample is transferred by means of said pressure differential from said first treatment station to said second treatment station, and maintaining the pressure differential between said first and second treatment stations after all of said first sample has been transferred to said second treatment station so that portions of said first sample deposited on the walls of the vessel of said first treatment station and said conduit are blown away cleanly with a jet of gas.

4. The method of claim 3, wherein the pressure differential is established by maintaining the pressure in said second treatment station at substantially 1 atmosphere and increasing the pressure in said first treatment station above 1 atmosphere.

5. The method of claim 3, wherein the pressure differential is established by maintaining the pressure in said first treatment station about 1 atmosphere and reducing the pressure in said second treatment station below 1 atmosphere.

6. The method of claim 3, further comprising transferring said first sample from said second treatment station to a third treatment station by means of a pressure differential established between said second treatment station and said third treatment station.

7. The method of claim 6, wherein a second sample is transferred to said first treatment station prior to the exiting of said first sample from said analytical system.

8. The method of claim 3, further comprising transferring a second sample to said first treatment station after the first sample has been removed therefrom, and transferring said second sample from said first treatment station to a third treatment station by establishing a fluid communication between the outlet means of said first treatment station and the inlet means of said third treatment station and establishing a pressure differential between the vessel interiors of the first and third treatment stations.

9. The method of claim 8, further comprising transferring said first sample from said second treatment station to a fourth treatment station arranged in series with respect to both said second treatment station and said third treatment station, and thereafter transferring said second sample from said third treatment station to said fourth treatment station.

10. The method of claim 9, wherein each sample is transferred from one of the treatment stations to a successive downstream treatment station by establishing a fluid communication between the outlet means of said one treatment station and the inlet means of said successive downstream treatment station and by establishing a pressure differential between the vessel interiors of said one treatment station and said successive downstream treatment station.

11. The method of claim 9, wherein the residence times of the samples in said second treatment station and said third treatment station are approximately twice the residence time of the samples in said first treatment station.

12. The method of claim 11, wherein successive samples passing out of said first treatment station are alternately transferred to said second treatment station and said third treatment station.

13. The method of claim 3, wherein said apparatus is arranged so that said treatment stations define at least one flow path for each sample, each sample travelling down its respective flow path in the forward direction only.

14. The method of claim 3, wherein said first sample is transferred from said first treatment station to said second treatment station by maintaining the pressure in said second treatment station approximately 1 atmosphere and increasing the pressure in said first treatment station to above 1 atmosphere, said process further comprising transferring a second sample from said first treatment station to said second treatment station by maintaining the pressure in said first treatment station about 1 atmosphere and decreasing the pressure in said second treatment station to below 1 atmosphere.