CA1149704A - Flexible diaphragm valve - Google Patents

Abstract

ABSTRACT

A valve for controlling the flow of liquid has a housing divided into first and second chambers by an air and liquid impermeable, flexible diaphragm. The second chamber has an air vent through the housing arranged so as to prevent the flow of liquid therethrough, an inlet and an outlet with the outlet being normally closed to air and liquid by the diaphragm. Liquid entering through the inlet under sufficient pressure to fill the second chamber contacts and exerts pressure against substantially all of the second chamber side of the flexible diaphragm to hydrostatically lift the diaphragm away from the outlet to thereby allow liquid to exit from the valve until liquid no longer fills the second chamber, whereupon the diaphragm will return to its normal position to again close the outlet to air and liquid.

Description

a7~34 The presen-t invention relates to a novel flexible diaphragm valve used in systems and equipment sets for the administration of medical liquids to a patient. This application is a divisional application of Canadian Application Serial No. 346,461, filed February 26, 1980.
The parenteral administration of medical liquids to patients is a long established practice. Liquids including amino acids, blood, dextrose, electrolytes, and saline are commonly administered to patients over prolonged periods of time. Generally, these liquids are administered from a glass bottle or plastic bag suspended above the patient and containing 250 - 2,000 ml. of the liquid. Such prolonged infusions commonly are administered at a flow rate of 10 - 150 ml./hr, Frequently, the patient must receive an additive or secondary liquid while the prGlonged infusion is being administered. Preferably, this secondary liquid should be administered through the same hypodermic needle to avoid unnecessary pain and trauma to the patient of additional venipuncture. To avoid dilution and incompatability problems r it is also preferred that the flow of the primary liquid employed in the prolonged infusion be temporarily interrupted, the secondary liquid administered and the flow of the primary liquid resumed. Generally, the secondary liquid will be administered at a flow rate of 50 - 250 ml./hr.

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~970~
Back~round Art Abbott Laboratories, North Chicago, Illinois manufactures a y-type set for the sequential administra-tion of primary and secondary liquids. These VENOSET (trade mark) piggyback sets allow the prolonged infusion of a primary li~uid to be t~mporarily halted by means of a backcheck valve in the primary liquid flow path to administer a secondary liquid without the need for a new venipuncture.
Them, when the secondary liquid has been depleted, the backcheck valve automatically opens to resume flow of the primary liquid. An important characteristic of this system is that the secondary liquid container must be suspended at a higher height than the primary liquid con-tainer to establish the liquid pressure differential that closes the backcheck valve in the primary liquid flow pathO
A similar system is disclosed in U. S. Patent 3,886,937 granted June 3, 1975 to D. Bobo, et al., as-signed to American Hospital Supply Corp., and entitled "Medical Administration Set for Dispensing Plural Medioal Liquids", Another similar system is disclosed in U. S.
Patent 4,105,029 granted August 8, 1978 to R. Virag, assigned to Baxter Travenol and entitled "Intravenous Solution Set ~aving An Air Access Site and Constricted Inner Diameter Portionn.
An inherent disadvantage of the above-mentioned prior art medical liquid administration systems is that they each resume the flow of primary liquid at the rate the secondary liquid had been flowing. Because the pre-ferred flow rate of the secondary liquid is generally greater than the preferred flow rate of the primary liquid, when the primary liquid resumes flow at that rate~
the patient can be administered an excessive amount of primary liquid, unless the flow rate of the primary liquid is adjusted to the preferred primary liquid flow rate soon after the flow of primary liquid resumes.
A remedy to the above~described disadvantage would appear to be provided by simply incorporating flow 7~
control devices into both the primary and secondary liquid flow paths. ~Iowever, while this remedy does provide dual flow rates for the primary and secondary liquids, it is unacceptable. That is, hecause the common tube of the y-set must be able to accommodate both flow rates, when the primary liquid is flowing at a slower rate than the secondary liquid was, there will be an unfilled volume or void in the common tube. To fill that void, air will be drawn into the common tube from the depleted secondary container. That air will then be drawn into the patient by the weight of the primary liquid, thereby causing a serious embolism and perhaps, the patient's death.
Accordingly, it will be apparent that an efficacious system for the sequential administration of medical liquids at dual flow rates would be advantageous to the medical profession.
Disclosure of Invention The present invention relates to a novel flexible diaphragm valve which may be used as the air barrier in the secondary liquid flow path of a system for administration of medical liquids. The diaphragm is substantially impervious to air and liquid to insure that no air is drawn from the secondary container when the secondary liquid is depleted.
Specifically, the invention relates to a valve for controlling the flow of liquid in a conduit, the valve comprising: a housing divided into first and second chambers by an air and liquid impermeable, flexible diaphragm, the first chamber having an air vent through the housing, and mb/-'~ - 3 ~

7(~4 the second chamber llaviny an ai.r vent through the housing and means associated therewith to prevent the flow of liquid therethrough, an inlet to be connected to the conduit for the entrance of liquid into the second chamber, and an outlet to be connected to the conduit for the exit of liquid from the second chamber, which the outlet is normally closed to air and liquid by the diaphragm, whereby liquid entering through the inlet under sufficient pressure to fill the second chamber will contact and exert pressure against substantially all of the second chamber side of the flexible diaphragm and hydrostatically lift the flexible diaphragm away from the outlet to thereby allow the liquid to exit from the valve until the liquid no longer fills the second chamber, whereupon -the flexible diaphragm will return ~.o its normal position to again close the outlet to air and liquid.
Brief Description of the Drawings Other objects and attendant advantages will become obvious to those skilled in the art by reading the following detailed description in connection with the accompanying drawing, wherein like reference characters designate like or corresponding parts throughout the several figures thereof and wherein:
FIG~RE 1 is a schematic block diagram of the efficacious system for the sequential administration of medical liquids at dual flow rates contemplated by this invention;

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FIGURE 2 - 5 are front elevation views of four medical liquid administration equlpment sets embodying the system of FIGURE l;
FIGURE 6 is a front elevational view of one em-. 5 bodiment of the efficacious equipment sets for the sequen-tial administration of medical liquids at dual flow rates contemplated by this invention;
FIGURE 7 is a front elevational view of another embodiment of the equipment sets contemplated by this invention;
FIGURE B is a front elevational view of an al-ternate version of part of the set of FIGURE 7;
FIGURE 9 is a front elevational view of one em_ bodiment of the efficacious equipment sets for the sequen-tial administration of medical liquids at dual flow rates contemplated by this invention;
FIGURE 10 is a front elevational view in cross-section of the flexible diaphragm valve depicted in FIG-URE 9;
FIGURE 11 is a front elevational view of another embodiment of the efficacious equipment sets for the se-quential administration of medical liquids at dual flow rates contemplated by this invention;
FIGURE 12 is a front elevational view in cross-section of the flexible diaphragm valve depicted in FIG-URE 11; and FIGURE 13 is a front elevational view in cross-section of an altern~te embodiment of the flexible dia-phragm valve of FIGURE 12.

Best Mode for Carrying Out Referring to the drawings, there is shown in FIGURE 1, a schematic block diagram of the basic elements of the gravitational flow system for the sequential ad-ministration of medical liquids at dual flow rates.

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The diagram depicts a primary liquid container 11 that contains a primary medical liquid to be admin-istered to a patient for a prolonged period of time. The diagram also depicts a secondary liquid container 13 that contains a secondary medical liquid to be administered to the patient for a relatively short period of time, during which time the administration of the primary liquid will be temporarily interrupted. As shown in the sets of FIGURES 2 and 5, containers 11 and 13 can be glass bottles, plastic flexible bags, or any other suitable container.
Primary container 11 and secondary con~ainer 13 are connected in fluid communication to a conventional hypodermic needle 15 through a primary tube 17, a second-ary tube 19, and a common tube 21. Thus, the primary liquid flow path from primary container 11 to needle 15 comprises primary tube 17 and common tube 21~ Likewise, the secondary liquid flow path from secondary container 13 to needle 15 comprises secondary tube 19 and common tube 21.
The distal end of primary tube 17 is in fluid communication with primary container 11, preferably by means of a piercing pin 23 inserted into a puncturable closure of container 11. Piercing pin 23 can have an integral drip chamber 25, and when container 11 is a glass bottle, as shown in the set of FIGURE 2, an inte-gral filtered air vent 27. Such piercing pins, drip chambers and air vents are well known in the medical prac-tice and need not be more fully explained here.
The proximal end of primary tube 17 is joined in fluid communication to the distal end of common tube 21, preferably by a y-tube 29, it being understood that the primary, secondary and common legs of y-tube 29 constitute a portion of the primary, secondary and common tubes 17, 19 and 21, respectively. Primary tube 17 has a primary flow control 31 intermediate its ends for independent adjusting the rate of flow of the primary liquid through the primary flow path. Preferably, as shown in FIGURES 2 - 5, primary flow control 31 can be ~ ~ ~9~
a roller clamp. However, it can be any other adjustable device that will reliably maintain a desired primary liquid flow rate.
The proximal end of primary tube 17 is joined in fluid communication to the distal end of common tube 21, preferably by a y-tube 29, it being understood that the primary, secondary and common legs of y-tube 29 con-stitute a portion of the primary, secondary and common tubes li, 19 and 21, rQspectively.
As shown in FIGURES 6 and 7, primary tube 117 may have a portion 130 having a constricted or reduced inner diameter for restricting the flow of primary liquid through primary tube 117 to a predetermined rateO As shown in FIGURE 7, primary tube 117 also includes a por~
tion 131 joined in parallel to constricted portion 130 by y-tubes 132. Portion 131 has a substantially larger inner diameter than reduced portion 130 and, accordingly, does not affect the flow rate of primary liquid through pri-mary tube 117. Portion 131 has slide clamp 134 that pre- 1 vents or permits primary liquid to flow through portion 131.
Alternatively, as shown in FIGURE 8, portions 130 and 131 can be provided with a common clamp 134a.
Clamp 134a is designed so that when it is slid to open con-stricted portion 130, portion 131 will be closed and vice versa. Returning to Figures 1-5, Primary tube 17 includes a primary valve 33 between its proximal end and primary flow control 31. Primary valve 33 allows primary liquid to flow from primary container 11 whenever the height of the primary liquid is greater than or equal to the height of the secondary liquid in the system of FIGURE 1~
Further, primary valve 33 prevents the flow of primary liquid from primary container 11 whenever the height of the primary liquid is less than the height of the second-ary liquid in the system.
While primary valve 33 has been shown in the sets of FIGURES 1 - 5 as being spaced from the proximal en~ of primary tube 17, it will be readily apparent that primary valve 33 can be incorporated into the primary leg of y-tube 29, if so ~esired. For example, primary valve 33 can be a co~ventional, one-way, backcheck valve mounted within the primary leg of y-tube 29.
The distal end of secondary tube 19 is in fluid communication with secondary container 13, preferably, by means o a piercing pin 35 inserted into a puncturable closure of container 13. Piercing pin 35 can have an integral drip chamber 37, and when container 13 is a glass bottle, as shown in FIGURE 2, an integral, filtered air vent 39. The proximal end of secondary tube 19 is joined in fluid communication to the distal end of common tube 21, preferably, by a y-tube 29.
An air barrier 41 and secondary flow control 43 are located in the secondary liquid flow path. Preferably, as shown in FI~URES 2 - 5, secondary flow control 43 can be a roller clamp. ~owever, it can be any other adjustable device that can reliably maintain a desired secondary liquid flow rate.
As shown in FIGURES 1 - 5, air barrier 41 is lo-cated in secondary tube 19, which is its preferred loca-tion. However, air barrier 41 can be located in common tube 21, if so desired. Likewise, for increased relia-bility of the system, a plurality of air barriers 41 can be located in either the secondary tube 19, common tube 21, or both. Further, while air barrier 41 is shown spaced from the proximal end of secondary tube 19, it will be readily apparent that air barrier 41 can be incorporated into the secondary or common tube leg of y-tube 29.
As shown in the set of FIGURE 2, air barrier 41 comprises a housing 44 having an inlet and outlet in fluid communication with secondary tube 19 and constitutes` a portion of it. Housing 44 is filled with a hydrophilic membrane filter 45 which is impermeable to air when wet.
The hydrophilic filters can be formed from materials such as a cellulose acetate material produced by the Millipore Filter Corporation of Bedford, Massachusetts or the Sartorius-Membranfilter GmbH of Weender Landstr, West Germany.

37~
The housing of each se~ shown in FIGURES 2 -5 also includes an air vent tube 47 having a slide clamp 49 and a filtered opening 50. Alternatively, opening 50 can be filtered by a hydrophobic membrane filter which is permeable by air, but not liquids. The hydrophobic filters can be ~ormed of polyfluorotetraethylene, hexa-fluoropropylene/tetrafluoroethylene copolymer, or other suitable materials. One such filter is made of Gelman ANH-450 material made by Gelman Instruments of Ann Arbor, Michigan. ~hen such a hydrophobic filter is used, slide clamp 49 can be eliminated.
Each embodiment of the system of FIGURE 1 shown in FIGURES 2 - 5 includes a slide clamp 51 near the-distal end of secondary tube 19 and a slide clamp 52 near the proximal end of common tube 21.
The air barrier 41 shown in the set of FIGURE 3 comprises a housing 53 that is substantially transparent and has graduations 55 on its sidewall that in~icate the - amount of liquid contained therein. Housing 53 has an ~l inlet and outlet in fluid communication with secondary tube 19 and constitutes a portion of it. The outlet from housing 53 is covered by a hydrophilic membrane filter 45. In the set of FIGURE 3, secondary tube 19 in-cludes a drip chamber 55 on the proximal side of air barrier 41.
The air barrier 41 shown in the sets of FIGURES
4 and 5 comprises a housing 63 that has an inlet and out-let in fluid communication with secondary tube 19 and constitutes a portion of it. The outlet from housing 63 has a float valve 65 which floats away from the outlet when liquid is present in housing 63, but seats or closes over the outlet when no liquid is present. It will be apparent to those skilled in the art that numerous other conventional mechanical valves can be employed to perform the function of float valve 65, so long as the valve forms a barrier impermeable by air when no liquid is present in the housing 63O

As seen in FIGURES 9 and 11, air barrier 241 and secondary ~low control 240 are located in the secondary liquid flow path. Preferably, as shown in FIGURES 7 and 9, secondary flow control 240 can be a roller clamp. How-ever, it can be any other adjustable device that can re-liably maintain a desired secondary liquid flow rate.
As shown in FIGURES 9 - 11, an air barrier 241 is located in secondary tube 219. While air barrier 241 is shown near the proximal end of secondary tube 219, it will be readily apparent that air barrier 241 can be more distally located on secondary tube 219, or incorporated into the secondary tube leg of y-tube 229, if so desired.
As shown in the set of FIGURE 9, air barrier 241 comprises a valve housing 242 having an inlet 243 and outlet 244 in fluid communication with secondary tube 219 and constitutes a portion of it. As best seen in FIGURE
10, housing 242 is divided into two chambers 246, 247 by an air and liquid impermeable, flexible diaphragm 248.
Diaphragm 248 is, preferably, made of elastomeric material, such as natural or silicone rubber. Diaphragm 248 can also be made of thermoplastic materials, such as poly-ethylene. As shown in FIGURE 10, diaphragm 248 can be captured between halves of housing 242. Alternatively, diaphragm 248 can be insert-molded into a single piece housing.
Chamber 246 has an air vent 250 through housing 242 by which ambient air can enter and exit. Chamber 247 has an air vent 252 through which ambient air can enter and exit. Air vent 252 is covered by a hydrophobic mem-brane 254 which is permeable by air, but not liquids. Thehydrophobic filter can be formed of polyfluorotetraethylene, hexafluoropropylene/tetrafluoroethylene copolymer, or other suitable materials. One such filter is made of Gelman ANH-450 (trade mark) material made by Gelman Instruments of Ann Arbor, Michigan.
As seen in FIGU~E 10, outlet 244, preferably, ex-tends into chanber 247 a substantial distance and its inner end 256 forms a seat on which flexible diaphragm 248 is nor-mally seated to close outlet 244 to air and liquid.
As shown in the set of FIGURE 11, air barrier 241 comprises a valve housing 262 having an inlet 243 and outlet 244 in fluid communication with secondary tube 219 and constitutes a portion o~ it. As best seen in FIGURES
12 and 13, housing 26Z is divided into two chambers 246, 247 by an air and liquid impermeable membrane 248. Cham-ber 246 has an air vent 250 covered by a hydrophobic mem-lQ 'brane 264~ Alternatively, as shown in FIGURE 13, air vent 250 can include a tube 265 having a filtered end 266 and a slide clamp 267 which can be slid to open vent 250 to the passage of air and closed to prevent the pas-sage of liquid.
Housing 262 has a port 268 therethrough and open-ing into'chamber 246. As seen in FIGURE 11, port 268 is connected in fluid communication to primary tube 217 by a 'pilot tube 269,-preferably, by means of a y-tube 270.
Pilot tube 269 has a slide clamp 271 thereon for controll-ing the flow of liquid through pilot tube 269. When slide clamp 271 is open, primary liquid can enter housing 262 to further bias flexible membrane 48 to its normally closed position. The entering primary liquid forces air from chamber 246 through vent 250. However, the primary liquid is prevented from flowing through vent 250 by hydrophobic membrane 264. When the alternative'embodiment of FIGURE
5 is used, slide clamp 265 must also be open to enable liquid to enter chamber 246 and slide clamp 271 can be eliminated, if so desired.
As shown in FIGURES 12 and 13, chamber 247 of housing 262 has an air vent 252 covered by a hydrophobic membrane 254. Alternatively, vent 252 can include a tube having a filtered end and a slide clamp similar to that of vent 250, is so desired. The inner end 256 of outlet 244 from chamber 247 is provided a plurality of protru-sions to form a plurality of seats on which flexible dia-phragm 248 can seat. Preferably, the plurality of pro-' trusions are formed by a plurality of concentric rings of ~ .

~ 9 70 ~
unequal heights, the height of the respective rings de-creasi.ny in a direction from the perimeter of inner end 256 toward its center.
In the set of FIGURE 4, primary tube 17 includes a primin~ tube 67 having a slide clamp 69 that controls the flow of primary liquid through priming tube 67. Prim-ing tube 67 is joined in parallel to the main branch o~
primary tube 17 by y-tubes 71, 72 located on each side of primary control means 31. As will be more fully ex plained in the following paragraphs, priming tube 17 allows primary control means 31 to remain at its preferred adjustment while the set of FIGURE 4 is being primed or backprimed at a higher flow rate.
Primary flow control 31 is shown on the distal side of primary valve 33 in FIGURES 1 - 5. It has been found that for pressure differentials of the magnitude occuring in the system o~ this invention, location of pri - mary flow control 31 on the proximal side of primary valve 33, for most of the preferred settin~s of primary flow control 31, results in a greater pressure being exerted in primary valve 33 by primary liquid than by secondary liquid. As a result, primary valve 33 remains open, as if the height o~ primary liquid were greater than or equal to the height of secondary liquid in the system.
Surprisingly, it has been found that when primary flow control 31 is located on the distal side of primary valve 33, as shown in FIGURES 1 - 5, certain em-bodiments of primary valve 33 might not remain closed as expected whenever the height of primary liquid is less than the height of secondary liquid in the system. This unexpected opening results from the reaction force on primary valve ~3 caused by primary liquid that cannot flow up~wardly past primary flow control 31 when primary valve 33 initially closes. This reaction force reopens valve 33 and keeps it open.
It has been found that this unexpected opening of primary valve 33 can be obviated by the inclusion in primary tube 17 of a chamber 75 for a compressible mass.

97~
As shown in ~IGUR~ 5, chamber 75 is located between primary flow control 31 and primary valve 33 and provides a cush-ion or ~pring for relieving pressures ont the distal side of primary valve 33 whenever valve 33 closes in response to the height of primary liquid being less than the height of secondary liquid in the system. Although pri-mary valve 33 and chamber 75 are shown as separate units in FIGURE 5, it will be apparent that they can be combined into one unit, if so desired.
As shown in the set of FIGURE 5, chamber 75 has a housing with an inlet and outlet in fluid communication with primary tube 17. ~owever, it is contemplated that chamber 75 can have only one opening in communication with primary tube 17. That is, chamber 75 may have a single opening transverse to the normal flow of liquid through primary tube 17 so that primary liquid only flows in or out of its single opening when reverse flow pres-sures exist on the distal side of primary valve 33.
Generally, the compressible mass of chamber 75 will be air and its housing will be a rigid opaque plas-tic. However, it is contemplated that the compressible mass of chamber 75 can be a sponge or other flexible solid materials, as well. Further, the housing of cham-ber 75 can be a flexible material which is compressible by the primary liquid to expand chamber 75, if so desired.
For simplicity, the equipment sets embodying the system of FIGURE 1 have been depicted and described as integral units of FIGURES 2 - 5. It-is apparent, however, that the sets can be manufactured and assembled in sub-sets of the entire set and that each subset will accord-ingly be provided such resealable closures, piercing means, adapters, etc. as are necessary to permit their easy assemblage into the complete set at an appropriate time.
It will also be apparent that each of the several compo-nents of the sets of FIGURES 2 - 5 can be interchanged or combined in combinations other than those specifically depicted.

Operation_o ~ y~
As depicted in FIGURES 2 - 5, primary container 11 is suspended in space at a height above the patient by means of a hook 77 and stand 79. It will be apparent that other means for suspending the containers of this invention are well known.
- To insure that all the air that might be forced into the patient has been removed from the set, the set is initially primed by first closing all slide clamps 49, 51, 52 and 69, if presen~. Piercing pin 23 is then inserted into the resealable closure of primary container 11. Primary flow control 31 and secondary ~low control 43 are fully opened. Slide clamp 52 is opened to allow primary liquid to flow through the primary liquid flow path and force all the air therefrom that might be forced into the patient. If chamber 75 is present in primary tube 17, a substantial volume of air will remain therein.
Slide clamp 52 is then closed.
In FIGURES 9 - 13, if inlet 243 to air barrier 241 is closed by a resealable closure at this time, second-ary tube 219 will have been backprimed whiie primary tube 217 was being primed. When secondary tube 219 is back-primed, chamber 247 will be flooded so that all of dia-phragm 248 will be contacted by primary liquid that will hyddrostatically lift diaphragm 248 from outlet 244 to fully open the valve. As primary liquid enters chamber 247, diaphragm 248 will flex away from outlet 244 and air will be expelled through air vent 252 in chamber 247 and air vent 250 in chamber 246. However, hydrophobic mem-brane 254 will prevent the flow of liquid through vent 252.
Clamp 49 on air vent 47 of air barrier 41 is then opened to allow primary liquid to flow into, or back-prime, secondary ~low path 19 and force all the air from air barrier 41. Slide clamp 49 is then closed. Alterna-tively, if the set is fully assembled, slide clamp 51 can be opened to allow primary liquid to force air out of the entire secondary tube 19. Slide clamp 51 is then closed.

~ 3'~ ~
During the initial priming of secondary tube 19, it is advan~ageous to hold secondary tube 19 at a height well below primary container 11. When secondary tube 19 has been primed, it is secured in a convenient place until its subsequent use.
Common tube 21, which preferably has an adapter at its proximal end open to the flow of liquid therefrom, is next connected to needle 15, which will generally have been already inser~ed into a vein of the patient. Slide clamp 52 will then be opened to allow primary liquid to flow th~ough the primary liquid flow path to the patient's vein. Primary flow control 31 is then adjusted to a set-ting that will provide the desired flow rate for a pro-longed infusion of primary liquid into the patient, generally 10 - 150 ml./hr. As is well known in the medi-cal practice, that flow rate can be visually observed by viewing and counting drops passing through the primary drip chamber 25.
In the set of FIGURE 6, flow control device 143 can be alllowed to remain fully open, so that the flow rate of primary liquid through primary tube 117 will be determined solely by the constricted or reduced inner diameter of portion 130~ Alternatively, or in the sets of FIGURES 7 or 8, whenever portion 131 is open to the flow of liquid therethrough, flow control 143 is then adjusted to a setting that will provide the desired flow ~ate for a prolonged infusion of primary liquid into the patient, generally 10 - 150 ml./hr. As is well known in the medical practice, that flow rate can be visually ob-served by viewing and counting drops passing through theprimary drip chamber 25. If the sets of FIGURE 9 are being used, slide clamps 267 and/or 271 are opened to allow primary liquid to enter chamber 246 of valve housing 262. If this pilot liquid enters chamber 246 before secondary tube 219 is fully bac~primed, it will not be possible to back-prime secondary tube 219 as the weight of the liquid will prevent membrane 248 from lifting away from outlet 244. It ~ ~t~
will be apparent that none of the pilot liquid entering chamber 246 through pilot tube 269 will be administered to the patient.
Secondary flow control 243 is then adjusted to a desired flow rate, typically 50 - 250 ml./hr., for the secondary liquid, which will flow until the secondary container 213 is depleted. It will be apparent that the initial liquid flowing from secondary tube 219 will be the primary liquid with which it was primed.
When the height of primary liquid in the sets of FIGVRES 9 - 11 becomes greater than the height of the secondary liquid, primary valve 233 will immediately open and allow primary liquid to flow from the primary con-tainer at the flow rate to whieh primary flow control 31 is adjusted. The primary flow rate is independent of the secondary flow rate. In those instances where it is less than or equal to the secondary flow rate, both primary and secondary liquid will flow through common tube 221, until air reaches air barrier 241 in the secondary tube.
Then only primary liquid will enter common tube 221. Air i barrier 241 then prevents air from being drawin into common tube 221 and eventually to the patient's vein.
Diaphragm 248 of valve housing 242 shown in FIGURE
9 will now seat against outlet 244 because of its own weight and elastic memory. Air will re-enter chamber 246 through air vent 250 as diaphragm 248 seatC. Secondary liquid will remain in chamber 2~7 at a level just below diaphragm 248~ As primary liquid flows through common tube 221 on the proximal side of diaphragm 248, it will create a reduced pressure that will tend to draw dia-phragm 248 into outlet 244 even further. In addition, diaphragm 248 of housing 262 will be further biased against outlet 244 by the weight of the primary liquid present in chamber 246, when that valve is employed.
When secondary container 213 becomes depleted of secondary liquid, it can be left empty until another secondary liquid is to be administered. When another secondary liquid is to be administered, the secondary ~ 370 ~
piercing pin 235 is merely removed from secondary contain-er 213 and inserted into a new secondary liquid container.
The pilot liquid must be drained from chamber 246, if present. The secondary tube 219 must then be backprimed, as when the secondary container was administered.
The set of FIGURE 3 can be employed to admini-ster a specific dose of secondary liquid to the patient by closing secondary tube slide clamp 51 when the desired amount of secondary liquid is in the calibrated cylinder 53. Air vent slide clamp 49 is then opened to allow the secondary liquid to flow from cylinder 53. However, while calibrated cylinder 53 is depicted at a lower height than primary container 11, in FIGURE 3, once secondary tube slide clamp 51 is closed, calibrated cylinder 53 must be raised to a height substantially above primary container 11, otherwise concomitant flow of the primary and secondary liquids will occur.

When the height of primary liquid in the system of FIGURE 1, as depicted in the sets of FIGURES 2 - 5, becomes greater than the height of the secondary liquid, primary valve 33 will immediately open and allow primary liquid to flow from the primary container at the flow rate to which primary ~low control 31 is adjusted. The primary flow rate is independent of the secondary flow rate. In those instances where it is less than or equal to the secondary flow rate, both primary and secondary liquid will flow through common tube 21, until air reaches air barrier 41 in the secondary tube. Then only primary liquid will enter common tube 21. Air barrier 41 then prevents air from being drawn into common tube 21 and eventually to the patient's vein.
When primary container 11 becomes depleted of primary liquid, the primary piercing pin 23 is merely re-moved therefrom and inserted into the resealable closureof a new primary container, which is then suspended in place of the previous container. If primary container 11 had become empty, it will be necessary to reprime the entire system as when the first primary container was administered.
When secondary container 13 becomes depleted of secondary li~uid, it can be left empty until another secondary liquid is to be administered. When another secondary liquid is to be administered, the secondary piercin~ pin 35 is merely removed from secondary contain-er 13 and inserted into a new secsndary liquid container.-The secondary tube 19 must then be backprimed, as when the first secondary container was administered~
Having described the invention in specific de-tail and exemplified the manner in which it may be carried into practice, it will now be readily apparent to those skilled in the art that innumerable variations, applica-tions, modifications and extensions of the basic prin-ciples involved may be made without departing from the sphere or scope.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A valve for controlling the flow of liquid in a conduit, said valve comprising:
a housing divided into first and second cham-bers by an air and liquid impermeable, flexible diaphragm, said first chamber having an air vent through said housing, and said second chamber having an air vent through said housing and means associated therewith to prevent the flow of liquid therethrough, an inlet to be connected to said conduit for the entrance of liquid into said second chamber, and an outlet to be connected to said con-duit for the exit of liquid from said second chamber, which said outlet is normally closed to air and liquid by said diaphragm, whereby liquid entering through said inlet under sufficient pressure to fill said second chamber will con-tact and exert pressure against substantially all of the second chamber side of said flexible diaphragm and hydro-statically lift said flexible diaphragm away from said outlet to thereby allow said liquid to exit from said valve until said liquid no longer fills said second cham-ber, whereupon said flexible diaphragm will return to its normal position to again close said outlet to air and liquid.

2. The valve defined in Claim 1, wherein said first chamber is further characterized by a port through said housing to be connected to a pilot conduit for the flow of a pilot liquid into and out of said first chamber and said air vent of said first chamber has means associ-ated therewith to prevent the flow of liquid therethrough, whereby said pilot liquid entering said first chamber serves to bias said flexible diaphragm against said outlet and liquid entering said outlet to said second chamber will contact an insufficient portion of said flexible diaphragm to hydrostatically lift said diaphragm away from said outlet, thereby preventing the flow of liquid into said valve through said outlet, when said outlet is closed by said pilot liquid.

3. The valve defined in Claim 1 or 2, wherein said outlet is further characterized in that its inner end extends into said second chamber to form a seat on which a portion of said diaphragm seats to normally close said outlet.

4. The valve defined in Claim 1 or 2, wherein said outlet is further characterized in that its inner end extends into said second chamber to form a seat on which a portion of said diaphragm seats to normally close said outlet, said inner end having a plurality of protrusions to form a plurality of said seats.

5. The valve defined in Claim 4, wherein said plurality of protrusions are concentric rings of unequal heights, the height of said rings decreasing in a direction from the perimeter of said inner end towards the center thereof.

6. The valve defined in Claim 1 or 2, wherein said means associated with said air vent of said second chamber is a hydrophobic membrane covering said vent.

7. The valve defined in Claim 2, wherein said means associated with said air vent of said first chamber is a hydrophobic membrane covering said vent.

8. The valve defined in Claim 1 or 2, wherein said means associated with said air vent of said second chamber is a flexible tubing having an air filter at its outer end and a flow control device thereon for controlling the flow of liquid through said tubing.

9. The valve defined in Claim 2, wherein said means associated with said air vent of said first chamber is a flexible tubing having an air filter at its outer end and a flow control device thereon for controlling the flow of liquid through said tubing.

10. The valve defined in Claim 1 or 2, wherein said inlet is covered at its outer end by a resealable membrane.