Air quality sampler

Abstract

A gas sampler is described for automatically collecting a plurality of different samples of a gas, such as from the atmosphere, at different time intervals. Such sampler includes a plurality of containers and associated pumps for collecting and retaining the samples. It further includes programmable control instrumentation for governing when a gas sample is collected into each of the containers. Each pump provides an average flow rate into its associated container by periodically starting and stopping operation during such period.

Description

BACKGROUND OF THE INVENTION

The present invention relates to monitoring a gas atmosphere and, more particularly, to a gas sampler which is programmable to automatically collect into individual containers, given quantities of an atmosphere at different time intervals.

In the study and handling of air pollution, it is often desirable to determine the character and concentration of pollutants at any given location at different times. For example, in studying pollution generated by automobiles in the vicinity of a highway or freeway, a comparison between traffic density and the resulting pollution is often important. Making such a comparison requires numerous measurements to be taken adjacent to the roadway at different times. Moreover, it is often desirable to determine whether or not pollutants from a known pollution sources are reaching a given location and, if they are reaching the location, when and in what concentration.

In order to obtain pollution measurements at differing times at a specific location, it has generally been necessary for personnel to be at the location at such times, and either make the measurement directly at the site or obtain a sample of the atmosphere at such site for later analysis in a laboratory. Neither of these procedures, however, is entirely satisfactory. The necessity for personnel to be at the site at the time of measurement not only adds to the expense, but reduces as a practical matter the number of differing sites which can be serviced in any given time period. In addition, on-site air pollution measurement apparatus is generally quite sophisticated and expensive.

SUMMARY OF THE INVENTION

The present invention is a simple and inexpensive air quality sampler which enables a plurality of samples to be automatically obtained from a given location at differing selected times. In its basic aspects, the apparatus simply includes a plurality of sample containers, such as inflatable, gas-impermeable bags, and pumping means for directing a quantity of the gas to be sampled into each of the containers. It further includes control instrumentation connectable with such pumping means for governing when the pumping means directs the gas sample into any one of the containers. With this arrangement, it will be recognized that with appropriate programming of the control instrumentation, samples of the atmosphere at the location of the apparatus can be collected at differing times and segregated for later analysis, merely by keeping track of which container receives a sample at any given time. Numerous samples can thus be taken at a remote location without the necessity of personnel being available during the sampling.

Most desirably, the control instrumentation includes programming means which permits an operator to change the time interval during which the pumping means directs a gas sample into each of the containers. The arrangement then enables an operator to "tailor" the apparatus to obtain air samples at any given site at those times deememd to be of most interest. Moreover the pumping means preferably includes a plurality of pumps, the output of each of which is connected with an associated one of the containers. The inclusion of a separate pump for each of the containers obviates the need for a complex valving and air plumbing arrangement and the necessary sophisticated control therefor. Moreover, the utilization of a pluraity of pumps, rather than a single, continuously operating pump, greatly increases the life expected from the system.

As another salient feature of the instant invention, it includes flow rate selection means for determining the rate of flow of gas into each of the containers during the time interval within which the pump associated with such control means is activated. Most effectively, such flow rate selection means varies the flow rate of the pump not by increasing or decreasing the operating pumping rate of the pump, but by periodically stopping and starting the operation of the pump during the full time interval when it is activated to take a sample. The resulting intermittent operation of the pump during the selected time interval provides the desired average flow rate, while also collecting gas from the atmosphere at times during the full time interval so that the resulting sample is an integration of the gas make-up during such full time interval. Intermittent operation of a pump to obtain a desired flow rate also eliminates the need for special (and more expensive) pumps having variable pumping speeds, besides resulting in a power saving advantage. That is, because the average power consumed by a pump at the typically low flow rates employed in gas sampling is directly related to its operating duty cycle, less power is used to periodically operate a pump than to continuously operate a similar pump providing the same overall flow rate. Additional power saving is obtained by utilizing for the power source, battery cells which recuperate between uses.

There are other advantages and features of the instant invention which will become apparent or will be described in connection with the following description of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the accompanying three sheets of drawings:

FIG. 1 is a partly broken-away, elevation view of a preferred embodiment of the air quality sampler of the invention;

FIG. 2 is an enlarged cross-sectional view of the top of the sampler of FIG. 1, illustrating the mechanism and instrumentation therefor;

FIG. 3 is a further enlarged view showing details of one of the pumps of the apparatus and its relationship to other components of the air sampler;

FIG. 4 is an enlarged top plan view of the cover on said air sampler, and

FIG. 5 is a schematic diagram of the control instrumentation for the air sampler and its relationship to other mechanisms thereof.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference first to FIG. 1, a stand-alone air quality sampler of the invention is generally referred to by the reference numeral 11. As is illustrated, such air quality sampler includes a protective enclosure 12 for housing collected samples of a gas, and an upper or cover portion 13 for the enclosure which also inclludes the operating mechanism for obtaining the gas samples. The protective enclosure is, as is illustrated, simply in the form of a barrel or similar housing. Most desirably, such enclosure is portable to enable the air sampler to be simply moved to any location at which it is desired to obtain samples. In this connection, the enclosure is desirably of a plastic or other lightweight chemically inert material. The capacity of the enclosure is dependent upon the desired total volume of gas it is desired to sample in any given intended use. For example, a barrel having a two foot diameter and three foot height will adequately contain and protect 24, 5-liter samples.

Each of the obtained samples is trapped within a container uniquely asociated therewith which segregates it from other samples. The gas containers are most simply gas impermeable bags 14 which are provided in a flat condition but which are inflatable by a gas sample as it is taken. It will be recognized, though, that other types of containers, such as liquid filled gas bubblers often used in the art, would also suffice.

Pumping means are provided for directing a sample quantity of the gas to be analyzed into each of the bags 14 when desired. More particularly, each of the bags is communicated via a flexible hose 16 with a nipple 17 extending through a bulk head 18 of the enclosure cover 13. A second flexible hose 19 communicates the upper end of each of the nipples with the flow output port 21 of a small piston pump 22 which is suitably mounted via bracket 23, for example, to the upper side of the bulk head. Associated with each of the pumps 22 is a simple, low operating power, dc driving motor 24.

From the above, it will be seen that a separate pump 22 and a driving motor 24 therefor is associated with each of the sample bags. Thus, at any time it is desired to obtain a sample within a particular bag, it is necessary to cause operation of the pump which is in communication with such bag. Although this provision of a plurality of pumps is a multiplication of similar parts, it has been found that the advantages gained by such a redundancy far outweighs the additional costs which might be involved. One of the primary advantages is the elimination of the need for complex and sophisticated valving and control mechanisms which would be required for appropriately divering gas to be sampled into the various containers if only one pump were provided. Moreover, as previously discussed, the utilization of a plurality of simple pumps results in both a significant power saving and an extended operating life for the system.

As illustrated, the pumps 22 are circumferentially mounted on the bulkhead 18 inwardly of the latter's outer circumference. The volume within which such pumps are located is separated from the external environment by a cylindrical particulate filter 26. The purpose of such filter is to prevent larger particles within the atmosphere from entering into the chamber of the pumps and fouling the same. An upper cover 27 is also provided having a downwardly extending peripheral skirt 28 to provide protection for the filter 26 from the elements.

The air sampler further includes control means for governing when each of the pumps directs a gas sample into its associated container. As can be seen from FIGS. 2 and 4, such control means, generally referred to by the reference numeral 29, is mounted on the underneath side of the bulkhead 18 centrally thereof. A suitable container 31 for a battery power source is also mounted to the underneath side of the bulkhead adjacent the control mechanism.

The control means is adapted to activate each of the pumps 22 during a discrete time interval selected especially for such pump and, hence, for filling of the container associated therewith. For a detailed description of the control means, reference is made to FIG. 5 which is a schematic logic and electrical diagram of the instrumentation thereof and its relationship to the pumps. The pumps are represented in such figure at 22' and are shown connected to gas containers 14' by hoses 16'. The power input to each of the pumps is provided by a pump driver 30 which is energized by an output terminal 32 of an associated gate 33. Energization of the inputs to each gate 33 in a manner to be described will result in the operation of its associated pump 22'.

As a particularly salient feature of the instant invention, the control instrumentation includes programming means, generally referred to by the reference numeral 34, which permits the selected time interval during which each of the pumps operates to be programmed or changed when desired. In this connection, the programming means include a second set of gates 36 whose output terminals 37 provide, in effect, control output connections for the programming means. That is, each of such control output terminals 37 is associated with a discrete time interval and, in this connection, is energized during such time interval by other aspects of the control means. The number of gates 36 and, hence, control output terminals 37 are dependent upon the number of time intervals that it is desired to be able to utilize during any one cycle of operation of the system. In this particular embodiment in which hour long samples are to be taken, 24 gates 36 and thus 24 different time intervals are provided, representing the 24 hours within a day. That is, each of the output connections is energized for a one-hour period during a day with each representing a particular one of the daily hours during which it might be desired to collect gas samples.

In order to provide proper, sequential energization of the output connections 37, the control instrumentation includes timing means, generally referred to by the reference numeral 38, for generating an output representative of the passage of time, and a time decoding means, generally referred to by the reference numeral 39 for receiving such output and sequentially activating the output connections during the time intervals represented thereby.

The timing means first includes an oscillator and divider 41, which provides a 60 hertz signal output. Such oscillator is, for example, a standard collector-base crystal feedback transistor oscillator, and the divider a conventional binary divider. The 60 hertz signal output of the oscillator and divider is fed to a timing processor 42. Such processor processes the 60 hertz signal into a plurality of time division multiplexed, time related outputs represented by flow line 43 which can be decoded with synhronous timing to appropriately drive a time display 44. The time display is, for example, a light emitting diode device of four digits representing hour and minute time divisions, the inputs of which are appropriately connected to the timing processor time related outputs.

The timing processor 42 also processes the 60 hertz input signal into binary coded decimal (bcd) outputs representing the passage of hours and minutes. As represented by flow line 48, the bcd outputs of the processor are connected to a memory 46 which stores the time representation of such output. The timing processor also directs strobe pulses to the memory 46 as represented by the flow line 45 synchronous with such timing pulses to cause storing in the memory of only that portion of the bcd output of the timing processor representative of the hour at any given time. Most simply, the memory is in the form of two four-element memories, one for storing the units of hour in bcd format and the other for storing the tens of hours in bcd format.

The timing means further includes time setting means for synchronizing its operation with an external time source. That is, time setting inputs to the timing processor for hours and minutes are appropriately connected through setting switches 49 to ground, to permit advancement of the outputs of the timing processor as necessary to synchronize the same with an external time source, such as a watch showing the actual time of day. The bcd output of the timing processor 42 and, hence, the output of the timing means is then representative of the time of day as well as the passage of time.

The time of day memory 46 output is fed to the time decoding means for appropriate decoding thereof and sequential activation of the control output connections so that each will be activated during a particular hour associated therewith during any 24 hour cycle. More particularly, the bcd output of the memory representing hour units is fed to a unit time decoder 51 which converts the same to the unit decimal equivalent and a corresponding energization of the appropriate one of the ten output terminals 52 representing the decimal equivalent of the binary input from the memory 46.

The bcd output of the memory representing the tens units in the decimal system is fed to a tens decoder 53 which provides the decimal equivalent thereof at its outputs 54. Since the particular embodiment being described is designed to provide a twenty-four hour cycle, the tens unit will only vary from "zero" to "two." This is the reason for only three outputs from the tens decoder rather than a full set of ten.

The output from the units and tens decoder are appropriately connected with the input terminals of the dual input gates 36 for sequentially activating the output connections 37 as described above. More particularly, the inputs to each of the gates represents the digits of the hour associated therewith. That is, one of the inputs of the first ten gates 36 (only five of which are shown) is connected to the first decade output as shown, and the other input of each of such gates is connected to the appropriate one of the unit time decoder outputs 52. This latter connection is represented in the drawing by a numbering of the gate inputs corresponding to a numbering of the unit time decoder outputs. Similarly, one of the inputs to the gates representing the hours 10 through 19 is connected to the second decade tens output of the decoder 54, and the other input to each is connected with the appropriate unit time decoder. Because the particular unit being described is designed for twenty-four hour cycles, only four gates 36 are shown with one of their inputs connected to the third decade output 54 of the decoder 53 and their other input appropriately connected to the first four unit time decoder outputs 52.

Simultaneous energization of both input terminals to any one gate will result in energization of that gate output. Thus, as will be recognized from the above, upon the decoding means providing an appropriate unit and tens output for each hour stored in the time of day memory, the proper control output connection will be energized. Thus, connection with a patch cord or the like between a control output connection 37 representing a particular hour and an input terminals 55 to a gate 33 associated with a chosen one of the containers 14' will result in such input terminal being energized.

The control instrumentation of the invention further includes time cycle control means which allows both remote start-up and samples to be taken at different times within sequential twenty-four hour periods without the necessity of an operator programming the same between cycles. Such control means is represented in the diagram by logic block 56. As illustrated, such logic includes "start cycle" logic in which an input thereto on 57 will result in an output on line 58 to enable mode logic represented at 47 which will respond thereto by applying an enabling signal to the unit time decoder 51 as represented by flow line 60. That is, until such time as the start cycle logic is energized, the output from the time of day memory 46 is not decoded by the unit time decoder, with the result that subsequent operation of the control unit dependent thereon is not initiated, and the output connections 37 cannot be energized. Thus, the start of the cycle of operation of the pumps is controlled by the enable mode logic. Such enable logic is desirably adapted to be energized by way of the start cycle logic either manually via switch 65 or remotely through input 57. The completion of operation of a similar, adjacent air quality sampler can provide the energization signal through the input 57 if, for example, it is desired to sequentially operate several air quality samplers at a single location.

The cycle timer logic further includes means for controlling a specific pump's operation during a plurality of 24 hours cycles. That is, the cycle timer receives input as indicated by the input terminal 80 from a patch cord connection to one of the output connections 37, representative of the beginning of the 24 hour cycle which the apparatus is starting at any particular time. The number of the cycle can be obtained by counting the number of times the chosen output connection 37 has indicated a particular hour.

The cycle timer responds to an indication that the apparatus is undergoing the start of a particular cycle by energizing one of the output terminals 59 representative of the particular cycle. This energization can be transferred with patch cords or the like to the input 79 of each gate desired to operate during any particular cycle. In this connection, appropriate patch cords are used which allow stacking so that it is possible to have the input 79 to a plurality of the gates 33 simultaneously connected to one of the cycle timer outputs 59 so that more than one pump 22' can be operated during any particular cycle.

The cycle timer further includes logic for cutting off power to the pumps and portions of the control apparatus both when a chosen cycle is completed and prior to application of an enabling signal to the start cycle logic, as well as to provide an output signal to initiate operation of another air quality sampler if desired. More particularly, the cycle timer also includes "cycle complete logic" which is programmable to be energized at a chosen time during operation of the control system. Such cycle complete logic includes an input 61 which can be connected with a desired one of the cycle timer outputs 59 to indicate the cycle during which it is desired that the operation be terminated. A second input terminal 62 to the cycle complete logic is connectable with a path cord or the like to a selected one of the output connections 37 representing the time during a particular cycle at which it is desired that the operation be terminated. Upon simultaneous energization of both of the inputs 61 and 62, the cycle complete logic puts out an output signal which is directed via line 63 to a switch 64 which is connected to the power source represented at 66 for terminating its application of power to the pumps and a portion of the control circuity upon such initiation. By this means the power consumption of the system, when not required to operate, is minimized. As illustrated, a manual switch 67 is also provided to enable an operator to manually control the operation of the system.

When power is initially applied to the system by closisng switch 67, the cycle timer logic 56 automatically assumes the cycle complete mode. Power is then applied only to the timing means 38 for time setting and monitoring at display 44. It is only when the start cycle logic is energized that the output signal on line 63 is removed and power is applied to the full system, allowing normal operation to start with the beginning of the first 24 hour cycle as chosen by input to the 24 hour cycle time at terminal 80.

The output from the cycle complete logic also energizes an output connection 68. Such output connection can be connected, for example, to the start cycle input 57 of the logic of another air quality sample to initiate the latter's standby mode logic and hence its cycling operation.

The control instrumention further includes flow rate selection means for determining the rate of flow of gas into each respective one of the containers during the time interval within which its associated pump is activated. As previously mentioned, such flow rate selection means provides the desired average flow rate over the time it is desired to pump a sample into a particular container by intermittently operating the pump, rather than varying the operating rate of such pump. The flow rate selection means is represented in the diagram at 71 and includes a sample timer 72 providing intermittent energization on an output line 73. As illustrated, the output of the sample timer is connected with the third input 74 of each of the gates 33. Moreover, a multiposition switch 75 is provided for selectively connecting into the sample timer 72, differing delay components represented at 76, 77 and 78. Such delay components affect the timer logic 72 by changing the ON/OFF time relationships at the timer output. It will be recognized that by selecting which of the delay components 76-78 is connected with the timer 72, the rate at which the input 74 of each of the gates is intermittently energized can be changed.

Each of the tri-input gates 33 will only provide an output and operate its associated pump when all three of its inputs are energized. That is, the gas to be sampled will be directed into a container only when its associated gate is programmed by suitable connections with the output connection 37 and the cycle connections 59 to do so. Furthermore, because of the flow rate selection connection to the input 74 of each of the gates, such gate will cause intermittent operation of the pump during such time to obtain an average flow rate.

From the above, it will be seen that the present invention provides an air quality sampler which not only enables a plurality of gas samples to be obtained at differing times without operator attendance, but also enables the same to be programmed quite readily and simply for varying the times during which the samples are taken in different operations. Changes and modifications to the exemplary embodiment described will be apparent to those skilled in the art. It is therefore intended that the coverage afforded applicant be limited only by the language of the claims and its equivalent.

Claims

We claim:

1. A gas sampler comprising a plurality of gas sample containers; a plurality of generally constant flow pumps, the output of each one of which is communicably connected with an associated one of said containers for respectively directing a quantity of the gas to be sampled into each of the containers; and control means connectable with said pumps for governing when each of said pumps direects a gas sample into its associated container, said control means activating each of said pumps to direct a gas sample into its associated container during a discrete time interval selected especially for said container and including flow rate selection means for determining the rate of flow of gas into said containers, said flow rate selection means being adapted to operate each of said pumps intermittently at its generally constant operating flow rate during the full time interval selected for each of said containers to thereby provide an average flow rate over the full time interval which is less than the continuous operating flow rate of said pump while still obtaining a gas sample representative of the gas over said full time interval; and said flow rate selection means being adjustable to vary the period of said intermittent operation of said pumping means during the time interval selected for each of said containers and thereby provide a selected one of a plurality of differing average flow rates for said pumping means.

2. A gas sampler comprising a plurality of gas sample containers; a plurality of generally constant flow pumps, the output of each one of which is communicably connected with an associated one of said containers for respectively directing a quantity of the gas to be sampled into each of the containers; control means connectable with said pumps for governing when each of said pumps directs a gas sample into its associated container, said control means activating each of said pumps to direct a gas sample into its associated container during a discrete time interval selected especially for said container and including flow rate selection means for determining the rate of flow of gas into said containers, said flow rate selection means being adapted to operate each of said pumps intermittently at its generally constant operating flow rate during the full time interval selected for each of said containers to thereby provide an average flow rate over the full time interval which is less than the continuous operating flow rate of said pump while still obtaining a gas sample representative of the gas over said full time interval; and a battery power source for operating said pumps.

3. A gas sampler comprising a plurality of gas sample containers; a plurality of pumps, the output of each one of which is communicably connected with an associated one of said containers for respectively directing a quantity of the gas to be sampled into each of said containers; and control means connectable with said pumps for activating each of said pumps to direct a gas sample into its associated container during a discrete time interval selected especially for said container, said control means including programming means permitting the discrete time interval during which said pumping means directs a gas sample into each of said containers to be changed, which programming means includes a plurality of control output connections, each one of which is associated with one of said discrete time intervals and said control means further includes timing means for generating an output representative of the passage of time, time decoding means for receiving said output from said timing means and sequentially activating said control output connections during the time intervals represented thereby, and means for selectively connecting each of said control output connections respectively with a selected pump to provide an energization signal to said pump for operation thereof to direct a gas sample into its associated container during the time interval represented by the control output connection so connected with said pump.

4. The gas sampler of claim 3 wherein said control means further includes time setting means for synchronizing the sequential activation of said control output connections with an external time source.

5. The gas sampler of claim 3 wherein said timing means of said control means includes an oscillator, a timing processor for receiving the output of said oscillator and providing an output representative of hour and minute time divisions, and a memory for holding each of the hour divisions of said timing processor for the duration of the hour represented thereby.

6. The gas sampler of claim 5 further including time display means for displaying hour and minute time division from the outputs of said time processor.

7. The gas sampler of claim 3 wherein said time decoding means includes a plurality of dual input gates, the output of each providing a respective one of said control output connections and the inputs thereto representing the digits of the hour associated therewith.

8. The gas sampler of claim 3 wherein said pumps are constant flow pumps; and said contol means includes flow rate selection means for determining the flow of gas into each respective one of said containers by periodically stopping operation of the pump associated therewith during the time interval selected for said container, and a plurality of gates having at least two input terminals, the output terminal of each respective one of said gates being connected to the power input of means for driving an associated one of said pumps, with one of the inputs being connectable to any one of said control output connections, whereby the output of each of said gates and consequently the operation of the pump associated therewith can only be enabled upon the simultaneous activation of said means for driving said pump by said flow rate selection means and the control output connection connected therewith.

9. The gas sampler of claim 8 wherein said control means further includes time cycle control means for initiating operation of each of said pumps only during a selected time cycle, and one of said gate inputs is connectable to the output of said time cycle control means to enable initiation of each of said pumps only during a selected time cycle.

10. A gas sampler comprising a plurality of gas sample containers, pumping means for directing a quantity of the gas to be sampled into each of said containers, and control means connectable with said pumping means for governing when said pumping means directs a gas sample into each of said containers, said control means including programming means permitting the selected time interval during which said pumping means directs a gas sample into each of said containers to be changed, which programming means includes a plurality of control output connections, each one of which is associated with one of said discrete time intervals, and said control means further includes timing means for generating output representative of the passage of time and time decoding means for receiving said output from said timing means and sequentially activating said control output connections during the time intervals represented thereby, and said control means further including time cycle control means for initiating operation of said pumping means during a selected time cycle and terminating the application of power to said pumping means upon completion of a selected time cycle.