Pressure Pumping System With Sealed Pressure Container

Abstract

New and improved pressure pumping system with sealed pressure container is provided and comprises means to supply the fluid to be pumped to said sealed pressure container from a substantially open, nonpressurized source thereof, and means to pressurize said sealed pressure container to pump said fluid therefrom. Means are additionally provided to maintain the level of said fluid within said sealed pressurized container substantially within a predetermined range.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new and improved pressure pumping system with sealed pressure container and, more specifically, to such system as is particularly adaptable for use in automatic, sequentially operable blood sample analysis means.

2. Background of the Invention

Although pressure pumping systems are known as described in greater detail hereinbelow for the supply of liquids in the nature of suitable color-producing reagents to automatic, sequentially operable constant flow rate blood sample analysis systems in the nature, for example, of those disclosed in U.S. Pat. No. 3,241,432 issued March 22, 1968 to Dr. Leonard T. Skeggs, et al., it may be understood that certain significant problems do arise in such use of the said prior art pressure pumping systems. More specifically, it may be understood that such prior art systems rely upon covered, pressurized reagent containers of relatively low reagent capacity to give rise to the problem, in the event that the said containers are not properly recovered after replenishment of the reagent supply therewithin, of hazardous leakage of highly pressurized reagent with resultant loss of the requisite substantially constant system reagent flow rate. In addition, and since the said relatively low capacity reagent containers are pressurized, it may be understood that the requisite periodic replenishment of the reagent supply therein will, of course, require correspondingly periodic system shutdown with resultant undesirable loss in system operating time.

OBJECTS OF THE INVENTION

It is, accordingly, an object of this invention to provide a new and improved pressure pumping system with sealed pressure container wherein the container for the fluid to be pumped at substantially constant flow rate is a sealed pressure container.

Another object of this invention is the provision of a pressure pumping system as above wherein the supply container for the fluid to be pumped is a substantially open, nonpressurized container, the supply of the fluid in which may be periodically and conveniently replenished without effect upon system operation.

Another object of this invention is the provision of a pressure pumping system as above which includes means for automatically controlling, in noncritical manner, the level of said fluid within said sealed pressure container.

A further object of this invention is the provision of a pressure pumping system as above which requires the use of only readily available components of proven dependability in the fabrication thereof to accordingly provide for long periods of satisfactory, maintenance-free system operation.

A further object of this invention is the provision of a pressure pumping system as above which, in one form thereof, is complete within itself and does not require any external source of system pressurization.

A still further object of this invention is the provision of a pressure pumping system as above which is particularly, though not exclusively, adapted for use in the in the supply of liquids in the nature of suitable color-producing reagents at substantially constant flow rate to automatic, sequentially operable blood sample analysis systems.

SUMMARY OF THE INVENTION

As currently preferred, the new and improved pressure-pumping system of the invention comprises a sealed pressure container having fluid inlet and outlet means. Pump means are provided to supply the fluid to be pumped from a substantially open, nonpressurized container thereof through said inlet means to said sealed pressure container, and means are provided to pressurize the latter at substantially constant pressure to pump said fluid therefrom through said outlet means. Fluid level control means are provided with said sealed pressure container and are operative to control said pump means in accordance with the level of said fluid in said sealed pressure container to maintain the latter within a predetermined range. In a first form of the invention, said container pressurization means take the form of an independent source of a suitably pressurized, distinct fluid which is connected to said sealed pressure container, while in a second form of the invention, said pressurization means take the form of said pump means, and fluid-directing means which are operatively associated therewith and with said fluid level control means and which are operable to enable pressurization of said sealed pressure container by said pump means.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of this invention are believed made clear by the following detailed description thereof taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic flow diagram of a pressure-pumping system constructed and operative in accordance with the principles of the prior art;

FIG. 2 is a flow diagram of a first form of a pressure-pumping system constructed and operative in accordance with the teachings of this invention; and

FIG. 3 is a schematic flow diagram of a second form of a pressure-pumping system constructed and operative in accordance with the teachings of this invention.

BRIEF DESCRIPTION OF THE PRIOR ART

A pressure-pumping system constructed and operative in accordance with the principles of the prior art for use in fluid analysis system is indicated generally at 10 and may, for example, take the form of that shown and described in the copending application Ser. No. 712,431 of Edward B. M. DeJong filed Mar. 12, 1968 and assigned to the assignee hereof.

More specifically, the pressure-pumping system 10 comprises a tank 12 of a suitably inert gas at suitable pressure, as for example nitrogen at 2,200 p.s.i. connected as shown through suitable pressure regulator means 14 to a branched conduit or manifold 16 to maintain the latter at a substantially constant pressure in the order, for example, of 66.8 cm. Hg.

Flasks 18 and 20, including screw-on covers 22 and 24, respectively, are provided and may be understood to respectively contain liquids in the nature, for example, of color-producing reagents for use in the fluid analysis system in the event the latter is constituted by a blood sample analysis system as discussed hereinabove, and the respective interiors of the said flasks are connected as shown by relatively short inlet conduits 26 and 28 to the branched conduit 16.

An outlet conduit 30 connects the interior of flask 18 to the inlet of a high flow resistance coil 32, and a conduit 34 connects the outlet of the coil as indicated to the fluid analysis system. In like manner, an outlet conduit 36 connects the interior of flask 20 to the inlet of a high flow-resistance coil 38, and a conduit 40 connects the outlet of the coil as indicated to the fluid analysis system.

For use in a representative blood sample analysis system, the respective internal diameters of the high flow-resistance coils 32 and 38 are made relatively small on the order, for example, of 0.010 inch or 0.25 mm., while the respective lengths thereof are made relatively long on the order, for example, of 210 inches for liquids, to provide the desired high flow impedance and attendant, relatively low flow rates. In addition, the respective high flow resistance coils 32 and 38 would be disposed in a temperature control bath as indicated in dashed lines at 42 which operates at a suitable temperature as, for example, 37.degree. C. to maintain the liquids passing through the said coils at substantially constant viscosity. If desired, the respective flasks 18 and 20, and the respective entireties of the outlet conduits 30 and 36 may also be disposed in the said temperatures control baths.

In operation, the gas from container 12 will pressurize the respective interiors of flasks 18 and 20 to force the liquids therefrom through the respective high flow-resistance coils 32 and 38 and therefrom, through conduits 34 and 40 at predetermined, substantially constant flow rates.

The flow rates of the liquids through the respective high flow-resistance coils 32 and 38 are determined by the Hagen/Poiseuille equation:

Q=.DELTA.P.pi.D.sup.4 /128 uL wherein:

Q is the flow rate;

.DELTA.P is the pressure drop across the coil;

D is the internal coil diameter;

u is the viscosity of liquid; and

L is the effective length of the coil.

Since the respective flasks 18 and 20 are, of course, highly pressurized during system operation, it may be understood that any failure to properly retighten the respective covers 22 and 24 thereof on the part of the system operator after replenishment of the supplies of reagents therein, as has in fact been observed to occur, will, of course, result in the hazardous leakage of highly pressurized reagent therefrom with attendant loss of the requisite constant reagent flow rate and resultant total system disability. Too, it may be understood that since the said flasks are, of necessity, of somewhat limited capacity, the respective reagent supplies therein must, of course, being periodically replenished and, since the system is pressurized, such reagent supply replenishment will require system shutdown with attendant undesirable loss in system operating time.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 2, a first form of a new and improved pressure-pumping system with sealed pressure container constructed and operative in accordance with the teachings of this invention for use, for example, in the supply of suitable color-producing reagents at substantially constant flow rate to automatic, sequentially operable blood sample analysis systems as discussed hereinabove with regard to said U.S. Pat. No. 3,241,432, is indicated generally at 44 and maybe seen to comprise an open reagent supply container 46.

A pump which may take any suitable form is indicated at 48, and the same includes a pump inlet conduit 50 which extends as shown into the lower portion of the reagent supply container 46.

A pressure container is indicated at 52 and the pump outlet conduit 54 extends thereinto as shown to enable the pumping of reagent from tee reagent supply container 46 to the pressure container 52 as should be obvious.

A container of a suitably pressurized and chemically inert gas in the nature, for example, of nitrogen at 2,200 p.s.i. is indicated at 56 and is connected as shown through suitable pressure regulator means 58 and conduit 60 to the interior of the pressure container 52 to suitably pressurize the latter.

An outlet conduit 26 extends as shown from the lower portion of the pressure container 52 to without the latter and a high flow-resistance coil 64 is connected as shown in the said outlet conduit. Preferably, a substantial portion of the outlet conduit 62, and the entire extent of the high flow-resistance coil 64, are immersed as shown in temperature control bath means 66 to maintain the temperature of the reagent flowing therethrough substantially constant and, in conjunction with the viscosity of the reagent, the pressure in the pressure container 52, and the respective length and internal diameter of the high flow-resistance coil 64, maintain the reagent flow rate through the said coil substantially constant for delivery therefrom to the blood sample analysis system as indicated by the arrow in the drawings.

Liquid level control means are indicated schematically at 68, and may be understood to be cooperatively associated as depicted with the pressure container 52, and with the pump 48 as indicated by the control line 70 extending therebetween, respectively, in such manner as to be operative to control the level of reagent in the said pressure container through suitable control of the operation of the said pump. More specifically, it may be understood that the said liquid level control means may take any suitable form in the nature, for example, of photoelectric or float operated switch means, which are in turn operative to energize and deenergize the pump 48 in accordance with the reagent level in the pressure container 52 to substantially maintain the said reagent level at a predetermined point or within a predetermined range in the said container.

Referring now to the form of the pressure pumping system with sealed pressure container of the invention as indicated generally at 72 in FIG. 3, it may be understood that the same incorporates many of the components of the system form of FIG. 2 and that the said components are identified by the same reference numerals in each of the said FIGURES.

In the system form 72 and FIG. 3, however, the pump 48 is continuously operable, and a three way valve is indicated at 74 and is disposed as shown in the pump inlet conduit 50 to control reagent flow therethrough. More specifically, the three way valve 74 may be seen to include a valve port 76 which is in communication with the atmosphere, and the said valve may be understood to be operative, in a first position thereof, to connect valve port 76 to the pump inlet conduit 50 with resultant pumping of air rather than reagent into the pressure container 52, and to be operative, in a second position thereof, to close valve port 76 and enable the pumping of reagent from the reagent supply container 46 to the pressure container 52.

Preferably, the three way valve 74 is operated between said first and second positions thereof by a valve-operating solenoid as indicated at 78, and it may be understood that the said valve-operating solenoid is in turn controlled from the liquid level control means 68 through control line 70 in such manner that the said valve will be moved to said second position thereof only when the reagent level in the pressure container 68 falls below said predetermined point to thus enable replenishment of the reagent supply in pressure container 52 by pump 48.

Alternatively, or that is to say with the three way valve 74 in said first position thereof, it may be understood that operation of the pump 52 and thus eliminate the need for the separate pressurization means 56, 58 and 60 of the system form 44 of FIG. 2.

A pressure relief valve 80 is provided as shown in the upper wall of the pressure container 52 to control the pressure to which the same is pressurized by the pump 48 when the three way valve 78 is in said first position thereof.

OPERATION

In the operation of the system form 44 of FIG. 2, the pressurization of the pressure container 52 at substantially constant pressure from the pressurization means 56, 58 and 60 will be effective to force reagent therefrom for flow at substantially constant flow rate to the blood sample analysis system through outlet conduit 62 and high flow-resistance coil 64.

As soon as the level of the reagent within the pressure container 52 falls below a predetermined point as established by the location and/or arrangement of the liquid level control means 68 relative to the said pressure container, it may be understood that the said control means will be effective to energize pump 48 to replenish the supply of reagent in the pressure container 52 from open reagent supply container 46. Once such reagent replenishment has been effected to the extent necessary to return the reagent level within the pressure container 52 to or above said predetermined point, the liquid level control means 68 will be effective to deenergize the pump 48 and maintain the same deenergized until reagent replenishment within the pressure container 52 is again required.

The operation of the system form 72 of FIG. 3 is generally similar to that of the system 44 of FIG. 2 with the exception that, in the former, the pump 48 is continuously operable and functions to both periodically replenish the supply of reagent within the pressure container 52 as well as to pressurize the latter for reagent pumping purposes at constant flow rate to the connected blood sample analysis system.

More specifically, with regard to the operation of the system form 72 of FIG. 3, it may be understood that with the reagent level at or above the predetermined point in the pressure container 52, the liquid level control means 68 will be effective to operate valve-operating solenoid 78 to place three way valve 74 in said first position thereof to enable pump 48 to pump air through valve port 76 into the pressure container 52 to pressurize the latter to the predetermined pressure as established by the setting of pressure relief valve 80.

Alternatively, once the level of reagent in pressure container 52 falls below said predetermined point, it may be understood that the liquid level control means 68 will be effective to operate valve-operating solenoid 78 to place three way valve 74 in said second position thereof to enable the pumping of reagent by pump 48 from the open reagent supply container 46 to the pressure container 52 to suitably replenish the reagent supply within the latter.

Of particular interest, and advantage, with regard to both of the pumping system forms 44 and 72 is the fact that the height or head of the reagent supply within the pressure container 52 is by no means critical to constant pressure and reagent flow rate system pumping operation and thus need not be precisely controlled, to in turn render unnecessary the use of liquid control means with particularly precise operating characteristics and attendant high cost. More specifically, it may be understood that the total additional pressure drop provided by this reagent supply head within the pressure container 52, and/or the variation in such total additional pressure drop as would accompany even a relatively large variation in reagent supply level, would be so small when compared to the overall system pumping pressure as to have no discernible effect upon reagent flow rate from the system, and this may be understood to be especially valid for proposed pumping systems wherein the total volume of the pressure container 52 is 50 ml. Too, and with specific regard to the pumping system form 44 of FIG. 2, it may be understood that the discharge pressure of pump 48 is by no means critical since the said pump functions solely to periodically replenish the reagent supply within pressure container 52.

In addition, it is believed clear that both system forms of this invention function to completely eliminate the very significant problems of hazardous, high pressure reagent leakage with resultant loss of the requisite pumping system constant flow rate, and the need for periodic system shutdown for reagent replenishment, which problems are attendant the use of capped reagent containers in the nature of those indicated at 18 and 20 in the depiction of a prior art pressure-pumping system of FIG. 1. More specifically, since pressure container 52 of the system of this invention is preferably a factory-sealed container, it may be understood that reagent leakage therefrom would be most improbable, while the periodic replenishment of the reagent supply in the open reagent supply container 46 may, of course, be conveniently periodically effected without requiring system shutdown.

Although as described hereinabove, the liquid level control means 68 are set forth to be operative immediately in response to a reagent level at a predetermined point in the pressure container 52, it may be understood that suitable timer means may, of course, be operatively associated with said liquid level control means in conventional manner to delay the operation thereof to a predetermined extent and prevent "hunting."

Too, although the new and improved pressure-pumping system with sealed pressure container of the invention has been disclosed for use in the pumping of a reagent at constant flow rate to a blood sample analysis system, it is believed clear that the system of the invention is suitable for a wide variety of other and different fluid pumping applications.

Claims

While we have shown and described the preferred embodiment of our invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

1. A pressure-pumping system for the pumping of a fluid therefrom at substantially constant flow rate comprising, a pressure container having fluid inlet means and fluid outlet means, respectively, means to supply said fluid to said container through said fluid inlet means, means to pressurize said container at substantially constant pressure to pump said fluid therefrom through said fluid outlet means at substantially constant flow rate, means operative in response to the level of said fluid within said pressure container to control said fluid supply means and maintain said fluid level within a predetermined range within said pressure container, said fluid supply means comprising a container of said fluid, and said fluid supply means and said means to pressurize said pressure container comprising pump means having inlet means extending into communication with said container of said fluid and outlet means extending into communication with said pressure container, fluid directing means disposed in said pump inlet means and operative in a first condition thereof to direct air into said pump inlet means for pressurization of said pressure container by said pump means, and operative in a second condition thereof to direct said fluid from said fluid container into said pump inlet means for supply by said pump means to said pressure container, means operatively connecting said means to control the level of said fluid in said pressure container with said fluid-directing means to operate the latter between said first and second conditions thereof in accordance with said fluid level in said pressure container, and means operatively associated with said pressure container to prevent the pressure therein from exceeding a predetermined maximum.

2. A pressure pumping system as in claim 1 wherein, said container of said fluid is open to atmospheric pressure.

3. A pressure pumping system as in claim 1 wherein, said pump means are continuously operable during operation of the system.

4. A pressure pumping system as in claim 3 wherein, said container of said fluid is open to atmospheric pressure.

5. A pressure pumping system as in claim 1 further comprising, high fluid flow-resistance means of predetermined internal flow diameter and length connected in said pressure container outlet means, and temperature control means operatively associated therewith for maintaining the temperature of said fluid flowing therethrough at a substantially constant level.

6. A pump system for an analytical conduit means, which analytical conduit means has a continuous flow and relatively low fluid flow resistance, and which resistance is subject to variation, for transmitting fluids, including liquid, therethrough, at a substantially constant rate of flow despite any such variation in resistance, comprising: a sealed container for liquid to be pumped having an outlet, means for supplying gas to said container to pass liquid therefrom along said outlet, a liquid reservoir open to atmospheric pressure, liquid supply means coupled to and between said reservoir and said container, a conduit for receiving said liquid from said container coupled to and between said outlet and said analytical conduit means and having a high-resistance coil crating a high resistance to fluid flow therein, and temperature control means for maintaining said coil at a substantially constant temperature for precluding variations in the viscosity of said liquid passing therethrough, whereby the rate of flow along said analytical conduit means is maintained substantially constant.

7. A pump system as defined in claim 6, wherein: said means for supplying gas to said container comprises a pressurized container of said gas.

8. A pump system as defined in claim 6 wherein: said means for supplying gas to said container and said liquid supply means comprise a pump alternately operable to pump gas and liquid to said container.