Abstract: A fuel pressure regulator is shown as having two distinct and variable chambers sharing, as a common wall therebetween, a pressure responsive diaphragm which controls the position of a valve actuator depending upon the pressure differential existing across the diaphragm with such pressure differential being reflective of the pressure differential existing as from the magnitude of the pressure of the fuel in a first of the two chambers to the magnitude of the pressure within the second of the two chambers which is at ambient atmospheric pressure; a flapper type valve openable by the valve actuator serves to control the flow of fuel into the first of the two chambers from where the pressure regulated fuel flows as to associated fuel metering apparatus.

Abstract: A mini-regulator valve assembly for providing a continuous supply of fluid at a predetermined pressure from a source of high pressure fluid. The valve has a first member adapted to join with the fluid source and a second member disposed for movement relative to the first member, one of the members forming a valve seal and the other forming a sealing edge cooperating therewith. The valve is further provided with a first biasing spring, a second biasing spring and an actuator. The first biasing spring biasing the second valve member against the first valve member and the second biasing spring acting on the actuator such that when the second biasing spring moved inward, the actuator acts on the second valve member moving the valve seat and edge away from each other thereby opening the valve, the first spring in combination with the pressure of the fluid passing through the valve ending close to the valve as the pressure builds up and thereby obtaining a regulating affect.

Abstract: A check valve to be interposed between a source of pressure and a device to be moved by the application of the pressure. The valve has a passageway communicating with the source of pressure and a passageway communicating with the device. There is a valve seat formed between the two passageways and a valve member contacts the valve seat. A valve stem can move the valve member to rest on the valve seat to close the valve but the stem is separate from the valve. With lessening of pressure in the source of pressure beyond a desired level the check valve may be closed. Movement of the valve stem to a position away from the valve member ensures that the valve will open but only when the pressure on each side of the valve is about the same. A particular application is to protect the lip of a head box in a paper making machine but may applications are possible.

Abstract: The invention is a lockout valve used in a hydraulic circuit to prevent leakage in a static condition; the lockout valve does not require outside force to hold the lockout open once flow across the lockout is established due to the positioning of an orifice ring around the poppet upstream of the poppet seat with the closing area acting on the poppet in conjunction with a spring which senses the pressure downstream of the orifice ring so that when there is sufficient flow across the orifice ring, the force created by the opening area on the poppet, which is located upstream of the orifice ring, will exceed the combined force of the spring and the closing area so that the lockout valve will remain open without an outside force so long as sufficient flow is maintained across the poppet.

Abstract: A flow limit valve for limiting the flow rate of a pressurized fluid includes a valve body with an interconnecting cavity of circular cross section. Within the cavity if a piston that slides within the cavity under force generated by a pressure differential across the piston to a closed position which prevents fluid flow through the valve. A pin is provided that is attached to the piston and that protrudes through the piston seat into the outlet side of the cavity when the piston is at the closed position. Opposite the pin is an encapsulated magnet within the valve body that can be moved in response to another magnet outside the valve body to contact the pin attached to the piston to move it to the open position. The magnetic forces applied through the valve body affect internal valve operation via the pin attached to the piston and this avoids the danger of noxious fluids escaping through sliding seals or flexible membranes.

Abstract: In a spring-loaded valve, a coil spring functions not only to bias a valve member toward its seat but also to retain the valve member in assembly with the valve.

Abstract: A combined pressure compensated exhalation and anti-suffocation valve assembly of the type which may find utility in an aviator's breathing mask. The valve assembly (14) includes a valve body (20) provided with an exhaust port (44) and a compensated pressure chamber (62) in communication with the mask cavity through an orifice tube (72). Disposed within the valve body (14) are a movable diaphragm assembly (22) and an exhaust port plate (24) supported by and movable toward and away from the diaphragm assembly.

Abstract: A hydraulic power supply system utilizing a turbine-driven pump in a hydraulic circuit and a solid propellant gas generator providing gas for driving the turbine. A gas pressure relief valve is operable to maintain the gas generator at constant pressure and has a range of pressure settings to vary the burn rate of gas generator and, thus, the power delivered to the turbine dependent upon the flow demands on the pump. There is a relatively low pressure setting when there is a reduced flow demand on the pump. The control provided by the settable hot gas relief valve reduces the size and weight of a number of components of the hydraulic supply system.

Abstract: Filling and discharging valve for inflatable hollow bodies, particularly dinghies, comprising a valve housing having a radial flange adapted to be attached to the inflatable body and a valve seat facing the interior of the inflatable body, the valve seat co-operating with a plate-like valve member. A spring is located within the valve housing and biasing the valve member towards the closed position thereof. Holding means hold the valve member in the opened position. A dead center spring above the valve member includes a dead center spring which is secured to the circumference of the valve housing. The dead center spring holding the valve member in its close position above the dead center and holds the valve member in its opened position below the dead center.

Abstract: A blow-off valve in the quick take-up master cylinder comprises first and second valves therein. The first valve is responsive to the fluid pressure built up in a primary pressure chamber. The second valve includes a valve member urged towards a valve seat thereof. The force urging the valve member of the second valve is adjustable according to the position of the first valve.

Abstract: A hydraulically unblockable non-return valve has a control piston (21), the control side of which can be connected with a control pressure medium source (35) and the other side of which can be connected with a supply container (33). In order to create a hydraulically unblockable non-return valve, in which the control side of the control piston does not need to be relieved of pressure, the other side of the control piston is perpetually connected with the supply container. Also provided is a throttle bore (27) which connects the two sides of the control piston with each other.

Abstract: A device for dispensing molten thermoplastic material which an operator grips while using his thumb to press a solid block of the thermoplastic material through a sleeve and into a heated melting chamber from which the molten thermoplastic material is discharged through a nozzle. The device includes a bracket adapted to hold a second block of thermoplastic material in end-to-end relationship with a first block in the sleeve, and a heated barrier ring at the inlet to the melting chamber that restricts escape of the molten thermoplastic material through the sleeve; and may also include a slidable pressure plate between the block and an operator's thumb and/or a trigger-operated outlet valve between the melting chamber and nozzle.

Abstract: A safety valve responding to overheating conditions of the surrounding atmosphere, more specifically a combustion gas inlet valve that closes when a fire declares. The valve uses a shape-memory element for detection and command. For the latter function it must be inside the valve, at the expense of sufficiently rapid detection of external temperature. This problem is solved by using a shape-memory element that is in close contact with the valve housing, e.g. countersunk in a groove in the internal wall of the valve housing, for facilitating conduction heat transfer.

Abstract: A relief valve (10) incorporating a poppet assembly (14) having a metallic sealing disc (46) in engagement with an annular valve seat (34). The disc is acted on by a ball (44) received within a recess formed in the end of the poppet stem (36). The disc and the ball are retained in free-floating relationship with the stem by means of a cylindrical retainer (40), which allows the ball to center itself over the disc and valve seat and thus effectively apply the closing force at a point at the center of the disc. The point application of the closing force causes the disc to flex a finite amount, which causes the disc to contact the inner edge only of the annular valve seat, thus approximating an ideal knife-edge engagement between the valve seal and the seat.

Abstract: The invention relates to a stop which is locked in position a bore of an operative device as well as to a device provided with at least one such stop. The stop is adapted for use particularly with, but not exclusively, with a safety valve. The stop includes a skirt adapted to be received in a bore and having at one end (29) by which it is connected to a centering dish (26), a diameter which adjusts itself practically without play in the bore (30) designed to receive the stop. At a second free end (31) the skirt has a diameter prior to positioning in the bore which is larger than that of the bore (30) intended to receive the stop so that, during the assembly, the skirt is compressed by the walls of the bore and thereafter, by reaction, it is forcibly pressed against the walls of the bore (30).

Abstract: A valve mechanism for low temperature applications comprising an outlet for a low temperature fluid, valve means for opening and closing said outlet, an axially movable rod having one end secured to said valve means and the other end extending outwardly to a normal temperature zone, means for holding said rod, resilient means located in said normal temperature zone for urging said rod toward a position wherein said outlet is closed by said valve means, and means for selectively applying a pressurized fluid to said rod to exert a force counter to said resilient means, whereby said rod and valve means may be displaced and said outlet opened.

Abstract: An improvement in ball-type check valve arrangements including a valve body in which is formed a fluid passageway and a valve chamber communicating through a valve seat in the chamber, a ball in the chamber seated in the valve seat, and a reciprocal retaining member having a head engaging the ball in opposition to the valve seat and a stem extending from the head through the chamber wall opposite the valve seat, the ball and retaining member being reciprocably movable toward and away from the seat.

Abstract: An air controlled valve assembly for a lumbar support device of the type having a plurality of parallel, horizontally disposed air bags located in the seat back of an automobile seat includes a hollow housing having a main air distribution chamber therein and a plurality of individual air supply chambers each of which is adapted to be connected to a respective air bag. A check valve is associated with each individual air supply chamber to control the flow of air under pressure from the main air distribution chamber to the respective air bags. The check valve is adapted to be spring biased into normally closed position against a valve seat and a spring guide member is interposed between the spring and the check valve. The spring guide member is formed with a plurality of radially extending circumferentially spaced apart projections, each of which has a partial circumferential surface adapted to be in sliding engagement with a hollow cylindrical bore.

Abstract: A safety valve intended to limit the pressure of a fluid contained in a vessel to which the valve is connected by a nozzle closed off by a flap-valve pressed against its seat by a spring acting on a first side of the flap-valve. The valve has two operating states; either the flap-valve is closed when the fluid pressure in the vessel acting through the nozzle on the opposite or second side of the flap-valve is below a pre-determined value or the flap-valve is open allowing fluid from the vessel to escape via an escape chamber in the valve when the pressure in the vessel is above the pre-determined value. A casing surrounding the spring is connected with the escape chamber by calibrated holes whereby the pressures in the casing and chamber are equalized. In addition to the spring, fluid pressure in the chamber acts on the first face of the flap-valve. When the flap-valve is closed, the fluid pressure in the escape chamber and casing is low.

Abstract: A master cylinder, according to the present invention comprises a primary piston and a secondary piston disposed within a bore of a cylinder housing in tandem relationship. The secondary piston has a sectional area facing to a secondary pressure chamber, which area is smaller than that of the primary piston facing a primary pressure chamber. The hydraulic pressure in the secondary chamber is regulated by a regulator valve means provided opposing thereto. The regulator valve means becomes operative when the hydraulic pressure applied to the secondary pressure chamber exceeds a predetermined value. Due to the difference of the sectional area between the primary piston and the secondary piston which respectively face to the primary and secondary pressure chambers, hydraulic pressure to be applied to the front and rear wheel cylinders is varied to reduce the pressure in the rear wheel cylinder for preventing skidding of the vehicle.

Abstract: The valve, in the exemplary embodiment shown, comprises a gas inlet or intake valve for use with a gas compressor. It has a valve body with a gas inlet opening and a gas discharge opening, the latter for communication with the gas inlet of a compressor. A pair of concentrically-engaged pistons, relatively movable therebetween, cooperate to open, close, and throttle communication between the valve inlet and discharge openings. A first, compression spring, reactive from the valve body, urges the piston pair in a first closure disposition, to prevent gas flow through the valve body, and a second, compression spring, reactive from one of the pistons of the pair thereof, urges the other piston to a second, open disposition, to accommodate gas flow through the valve body.

Abstract: A simple, reliable pressure control valve for a medical device having a hydraulic system comprises a valve housing having an open top and a bottom and an inwardly directed shoulder partially closing the top; a poppet with an upwardly extending stem mounted in the housing between the top and the bottom; a sealing edge mounted on the poppet circumferentially about the stem, and a calibrated spring urging the poppet towards the open top of the housing so that the sealing edge is in sealing contact with the underside of said shoulder and the stem extends above the top of said housing so that manual pressure can be exerted upon the stem to open the valve or the valve can be opened by a hydraulic pressure which exerts sufficient force upon the top of the poppet to overcome the force of the spring.

Abstract: A valve which controls either the injection of fluid from an exterior source into the interior of the valve housing or the exhausting of fluid pressure from the valve housing. The valve is especially adapted for controlling the injection of fluid into a wireline lubricator assembly. Alternative means are provided for opening and closing the valve. Preferably a metal-to-metal seal is used to control fluid flow.

Abstract: The thermostat mounting assembly is used to support a thermostat at a location between an engine block and a radiator. The housing has a fluid inlet port and a fluid outlet port with a support assembly used to rigidly fix the thermostat in place within the housing. A manually operable mechanism is connected to the housing to effect a continuous flow of coolant liquid to by-pass the position of the thermostat between the engine block and the radiator.

Abstract: An air brake system augments the braking force available while parking without interfering with the operation of the parking brakes. The brake system includes a service brake, a pilot check valve and, typically, a quick release valve. The quick release valve and pilot check valve are interconnected in two alternative ways among the service and spring brake lines and the service brake cylinder. When the spring brake line is pressurized the system acts normally. However, when the pressure on the spring brake line is eliminated the pilot check and quick release valves trap the pressurized air within the service brake. This keeps the service brake for each individual wheel actuated. Pressurizing the service brake line pressurizes the service brake regardless of the condition of the spring brake line. Safety valves can be incorporated in the brake systems to insure that the pressure within the service brake chamber does not exceed a predetermined value.

Abstract: An electriclly actuated, spring biased closed solenoid valve comprising a valve actuating coil, a valve bias spring, a valve plug and a valve seat is adapted to be mechanically actuated by an hydraulic actuated piston actuated by hydraulic fluid in a second fluid channel and having means for cushioning release of the piston from the solenoid valve to prevent hydraulic hammer when the solenoid valve plug stops the flow fluid in the main fluid flow channel. The solenoid valve is also adapted to open under hydraulic back-pressure against the valve seat when the back-pressure exceeds the pressure of the normally closed spring bias.

Abstract: A hot water system in which a damped, gravity operated, check valve is interposed between the hot water heater and the hot water delivery pipe network. The valve opens when a tap is opened allowing hot water to pass into the pipes and to the tap. The valve is prevented from closing abruptly when the tap is closed by a close fitting cylinder which surrounds the valve piston and restricts fluid flow necessary for valve closure.

Abstract: A snap-on, easily removable, fluid shut off valve (with pipe and interlocking member) that is useful as a low cost, primary turn off valve for domestic and commercial fluid fixtures and is quickly installed by manual snap-on between the inlet fluid supply and the supply pipe to conventional fixtures such as faucets or the like. The valve comprises a rigid housing having an inlet chamber and an outlet chamber, and a cross-over passage separating the first and second chambers that houses a moveable ball or poppet valve member that is held in the cross-over chamber by a spring retainer. A mechanical plunger or cam device (operable from the exterior of the housing) is disposed within the outlet chamber for contacting and pushing the ball or poppet valve member against the spring retainer, away from the valve seat, to open the valve.

Abstract: In a high pressure hydraulic system wherein a source supplies pressurized fluid to a slave unit through a control valve operative to maintain the slave unit in a desired condition, leakage from the slave unit past the control valve when the source is inoperative is prevented by a control valve comprising two solenoid-operated valves, oppositely acting and arranged in series between the source and the slave unit, each valve being closed to prevent flow through the valve in a direction towards the other valve and opened to permit flow in both directions, under the control of a solenoid and the pressure differential acting across the valve. A seating portion on the valve located between the other valve and the slave unit is of elastomeric material to provide a leakproof seal when that valve is closed.

Abstract: An automatic valve for a pressure suit. The valve has a valve body with an inlet port therein having an actuable valve member to admit pressurized gas in a valve chamber in communication with a suit to which the valve is secured. An adjustable cover member is displaceably secured to the body and has at least one exhaust orifice. An outlet port is provided in the body and communicates with the valve chamber and has an automatic pressure regulating valve mechanism therein. The valve mechanism is adjustable by a pressure biasing member controlled by a first displacement of the adjustable cover member to control the pressure of the gas in the suit by automatically exhausting some of the gas through the outlet port when the internal pressure exceeds a preset pressure of the mechanism. A displaceable valve member is associated with the valve mechanism and displaceable by a second displacement of the cover member to exhaust gas from the valve chamber and the inside of the suit through the outlet port.

Abstract: A spring-loaded safety valve has a housing with inlet and outlet, a valve member mobile between open and closed positions, a valve spring urging the valve member to the closed position and having a tendency to vibrate during the operation of the valve, and vibration-disturbing element for damping the vibrations of the valve spring during the operation of the valve. The vibration-disturbing element may be formed as a damping load or a damping spring which urges a valve spindle in direction of opening of the valve.

Abstract: An accumulator device is characterized in the provision of plural mechanisms for maintaining the oil port sealing valve member in open position, one said mechanism comprising a spring and the other comprising a control device member which may be activated to its valve stem releasing condition responsive to pressure drops of a predetermined magnitude or after a predetermined time interval.

Abstract: A relief valve (10) having both spring biasing means (116) and air pressure biasing means (114). The spring biasing means (116) includes a plurality of spring washers (132) acting between the valve body (12) and a valve member (74). The air biasing means (116) includes an air cylinder defined by an intermediate portion (20) of the valve body (12), and a piston (118) disposed within the cylinder and acting on the valve member (74). An air inlet port (48) is provided above the piston (118) to permit the area above the piston (118) to be pressurized to add to the biasing force of the spring biasing means (116), and an air inlet port (52) is provided below the piston (118) to permit the area below the piston (118) to be pressurized to open the valve manually for testing and exercising. A "quiet" element (102) surrounds the valve member (74) to reduce the sound level of the fluid flowing through the valve when the valve opens.

Abstract: A pilot operated check valve for high pressure service utilizing an O-ring is disclosed, wherein a poppet valve having a seating surface for engagement with a valve seat is provided on its front side with a spool member formed integrally therewith and projecting axially therefrom, an O-ring mounting groove is provided on the spool member in abutment relation with the seating surface of the poppet valve opposed to the valve seat so that the O-ring mounted in the groove may be positioned in a fluid passageway extending through a partition wall between primary-side and secondary-side fluid compartments. The spool member has a passage for fluid flow formed on it which extends from its front end facing the primary-side fluid compartment to the surface of the spool member adjacent the O-ring mounting groove.

Abstract: A device for blocking or releasing the flow of a gaseous or liquid medium therethrough by means of a valve ball which is situated in a valve seat includes a release bar which can be moved such that the valve ball is moved relative to the valve seat. The longitudinal axis of the release bar is disposed at an angle in the range of 20.degree.-100.degree. to the direction of flow of the gaseous or liquid medium.

Abstract: A vacuum breaker for use on a moving tank for allowing atmospheric air to enter the tank to relieve a reduced pressure condition in the tank. The vacuum breaker has a light-weight closure assembly including a closure member of relatively large area. The closure assembly is normally held closed by permanent magnets. The magnets and the light-weight construction of the closure assembly substantially prevent the vacuum breaker from opening due to vibration of the moving tank. However, the vacuum breaker opens readily in response to a relatively slight reduced pressure in the tank because of the large area of the closure member. The permanent magnets are shielded from undesirable proximity of ferrous objects to prevent the magnets from being drained. The vacuum breaker may be opened manually to test for a positive pressure condition in the tank.

Abstract: A system for filling and emptying a fluid storage tank includes an air pressure source 11, a vent valve 12, and a fill valve 14. The vent valve 12 includes first and second housing portions 23 and 24 and a main valve member 18. A coil spring 20 acts between the second housing portion 24 and a valve stem 19 to close the main valve member 18 and to bias the housing portions 23 and 24 together. A piston 21 cooperates with the second housing portion 24 to define an expansible chamber 39, and air pressure from the source 11 enters the chamber 39 to move the piston 21 and open the main valve member 18. A secondary valve member 40 isolates the fill valve 14 from the air pressure source 11 until the main valve member 18 is opened, and then communicates air pressure to the fill valve 14 to open the fill valve 14 and permit filling or emptying the tank.

Abstract: A valve disc is capable of moving between a closed position in which it seals-off an opening formed in an enclosure and an open position in which it is withdrawn from the opening. The valve disc is maintained in its closed position when the pressure within the enclosure is below a predetermined value by means of back-pressure exerted by a pneumatic jack. Coupling means are provided for disconnecting the jack from the valve disc in the event of a fast pressure rise within the enclosure.

Abstract: A device for metering liquids, which device comprises a body, a liquid conduit in the body, vibration means for vibrating the body, a valve for opening the conduit when the body is being vibrated and for closing the conduit when the body is not being vibrated, and a conduit external of the body and arranged to conduct liquid towards or away from the conduit in the body, the device being such that in operation liquid fed along one of the conduits is metered along the other conduit by activating the vibration means for a desired liquid metering time to cause the valve to open the conduit in the body.

Abstract: A crawler tractor has an engine-driven transmission for supplying motive power to the left and right crawler tracks through spring-applied fluid-released left and right steering clutches and also has spring-applied fluid-released track brakes. A hydraulic steering clutch and brake control system is provided and includes left and right manually operable steering levers for the clutches and a single foot-operated brake pedal. The control system further includes a single pump for supplying hydraulic fluid to the steering clutches and to the brake actuators for the brakes. A steering valve, having a flow divider therein, receives fluid from the pump and is responsive to actuation of the steering levers to supply fluid to release the steering clutches. The steering valve also continually directs fluid to a pilot operated shuttle valve which is responsive to operation of the steering clutches to direct operating fluid to the brake actuators to effect brake release for that track whose clutch is engaged.

Abstract: A valve for relieving pressure in a container including an adjustably spring loaded poppet wherein the adjusting means therefor is covered by an actuator knob which drivingly engages the poppet which knob is operable to move the poppet to and from its operative sealing position through engagement of a projection formed in the knob with a cam surface formed on the valve housing. Indentations in the cam surface retain the knob in positions corresponding to sealing and open positions of the poppet.

Abstract: A signal device comprising a balloon, a balloon adaptor attachable to the balloon and having a hollow extension with a seat at one end thereof which end is extendable into the balloon, a sealing or valve member spring-biased on the seat of the balloon adaptor, and a supply adaptor. The supply adaptor includes a hollow stem which can be inserted into the hollow extension of the balloon adaptor so that the end of the stem lifts the sealing member from the seat against its spring-bias, so that ports formed in the hollow stem communicate with the interior of the balloon.

Abstract: A remote-controlled tubing safety valve having a check valve and a remotely controlled valve member operator movable between two positions. When the valve member operator is in a first position the check valve is maintained open. When the valve member operator is in a second position it does not interfere with the operation of the check valve. This abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

Abstract: A valve assembly comprises a valve body having a bore therein, a first opening communicating with the bore, and a second opening displaced from the first opening and also communicating with the bore. A valve element is slidably mounted in the bore for longitudinal movement therein between first and second positions. In the first position the first opening is sealed from communication with the second opening, and in the second position communication between the first and second openings is permitted via the bore. The valve element includes a pressure reaction area exposed to fluid pressure from the second opening in the second position whereby the valve element is retained in the second position upon the presence of fluid pressure in the second opening in excess of a given limit. The assembly further comprises return means for automatically returning the valve element to the first position upon the absence of fluid pressure above the limit in the second opening.

Abstract: A non-return air flow system for supplying secondary air into the exhaust system of internal combustion engines by utilizing pulsating flow of exhaust gases in the exhaust system, wherein the critical valve opening pressure for a check valve incorporated in the non-return system is varied in accordance with intake air flow rate of the engine so that supply of secondary air is effected in proportion to air intake of the engine.

Abstract: Sub-surface water is pumped through a bore hole to an oil-bearing formation by a pump installation in the bore hole including a submergible pump and an adjustable control valve at the discharge side of the pump. The control valve closes automatically when the pump is not operating to prevent reverse flow and loss of flooding pressure and to insure a back pressure on the pump during starting, and is controlled hydraulically from the surface of the earth to vary the flow to the oil-bearing formation. A novel control valve structure provides accurate and reliable control without unduly restricting the flow volume.

Abstract: A cartridge type check valve which may be either pilot operated or of the free flow type. The pilot operated type includes in combination a generally cylindrically-shaped housing having first and second end portions and having internal wall means defining an opening extending axially therethrough. A valve seat is formed on the internal wall means and a valve member is movable into and out of engagement with the valve seat to selectively prohibit and permit fluid flow through the axially extending opening at the valve seat. A fluid port is provided in the first end portion of the housing and serves to provide for fluid entrance into the axially extending opening. A control piston is positioned in the second end portion of the housing and is movable between first and second positions as is a valve stem, which is connected to the valve member and extends axially to a position adjacent the control piston and is adapted to be engaged and moved by the control piston.

Abstract: A general anesthesia rebreathing system comprised of a disposable portion adapted to be easily coupled to and decoupled from a permanent portion. The system is designed so as to minimize the structural complexity and cost of the disposable portion while assuring that the disposable portion includes all elements which are likely to contaminate gases inhaled by a patient. The disposable portion includes conventional breathing tubing for coupling a source of fresh gas, as from an anesthesia machine, to a patient and in addition an overflow tube for coupling the patient end of the system to an overflow (pop-off) valve, preferably mounted on the machine and constituting part of the permanent portion. The overflow tube entrance is located close to the patient end of the system and in communication with the tubing which conveys expired gas to a reservoir, such as a conventional breathing bag, mounted at the machine end.