Apparatus for combining fluid flows in variable proportions is adapted for blending an active constituent gas and a diluent gas to calibrate gas analyzers used in monitoring pollution. Diluent gas passes from source 34 through a downstream differential pressure regulator 17 and a constant flow restrictor 12 to outlet 14 which communicates with control port 20 of regulator 17. Active gas passes from source 35 through differential pressure regulator 23, through three fixed parallel flow restrictors 22, 29 and 30 to combine with the diluent gas upstream of restrictor 12. Control port 26 of regulator 23 communicates with the input to restrictor 12. Switching of valves 31, 32 and 33 varies the rate of flow along conduit 16 and hence the proportions of gases combined upstream of restrictor 12. Regulator 23 maintains flow along 16 substantially constant for given valve settings, and regulator 17 maintains flow along outlet 14 substantially constant despite changes in flow rate in the conduit 16.

Fluid flow apparatus and method

A valve assembly for mixing air and oxygen in a medical respirator over a wide range of volumetric flow rates, without sacrificing relative mixing accuracy at the lower flow rates. The assembly is divided into a plurality of mixing valve modules characterized respectively by progressively increasing volumetric flow capacities and progressively decreasing absolute mixing accuracies. The higher flow capacity modules are sequentially brought into operation as the overall valve flow increases and then interrupted when the flow decreases below a threshold level associated with each module. The valve assembly accordingly has a large range of flow capacities without degrading absolute mixing accuracy during low flow rate conditions by the effect of the higher capacity modules.

Multistage mixing valve for a medical respirator

A valve drive device includes a valve seat plate in which an inflow port and an outflow port for fluid are formed, a sealing case covering the front face side of the valve seat plate, an inflow pipe and an outflow pipe which are fixed in the rear face side of the valve seat plate so as to be in communication with the inflow port and the outflow port, and a valve element which slides on an area where the outflow port is formed on the front face side of the valve seat plate to open or close the outflow port. The valve seat plate includes a first plate member which constructs an area where the outflow port is formed, a second plate member which is thinner than the first plate member and is jointed with the first plate member, and a deformation preventing member which is attached on the rear face of the second plate member and prevents the second plate member from being deformed due to an internal-pressure in a sealed space constructed by the sealing case and the valve seat plate.

Valve drive device

The improved gas flow control apparatus controls the flow of multiple gases to a tonometer for calibration of a blood gas or pH sensor and compensates for the failure of gas supply solenoid valves to operate properly in controlling gas flow. Intermediate gas supply solenoid valves select between gas flow of the supplied gas in an open position, and venting to the atmosphere in a closed position. A common selector valve is also provided in the gas flow path to the tonometer to select gas flow from one of the intermediate gas flow valves. A control unit is provided for controlling the operation of the intermediate and common selector valves.

Method and apparatus for flow control for sensor calibration

A system is disclosed for providing an interconnection between two needle valves such that movement of either needle valve, in opening or closing thereof, is affected or limited by movement of the other valve. The invention is particularly suited to an anesthesia machine wherein separate supplies of oxygen (O 2 ) and nitrous oxide (N 2 O) are fed to individual needle valves which are then individually adjusted to provide a desired mixture of N 2 O and O 2 for administration to a patient to anesthetize the same. The system herein disclosed interconnects the individual needle valves such that the O 2 needle valve may be opened fully without restriction, however, when the N 2 O valve is open, the interconnection provides that closing of the O 2 valve will, at a predetermined point, also correspondingly close the N 2 O valve, thus preventing the percentage of N 2 O in the mixed gas from raising above a set value, i.e. one at which sufficient oxygen for a respirable mixture is assured. Similarly, the N 2 O valve is prevented, through the same interlock system, from being opened beyond a point where the N 2 O percentage could exceed such limit. Again, when the N 2 O valve reaches the predetermined point, further opening of the N 2 O valve also opens the O 2 valve such that the flow can be increased by further opening of the N 2 O valve but the percentage of N 2 O and O 2 will thereafter remain constant. In addition, the overall system has a further preventative feature where the flow of oxygen cannot be set below a predetermined value so that sufficient oxygen flow to the patient is assured.

Anesthesia machine having proportion limiting control system

Gases under pressure are mixed by directing the gases through two separate conduits while the pressure in one of the conduits is regulated by a pressure regulator to a desired mixing pressure and the pressure in the other conduit is passed through a pressure valve which is operated in proportion to the regulated pressure in the first conduit. The gases are then directed through separate throttles in the respective conduits to a common mixing line while the valves of the throttles are regulated together in order to vary the mixing ratio and the flow area through each throttle while the combined flow area is maintained constant. The throttle valves include valve members which are movable in respect to the associated valve seat to provide a constant variation of the flow area for the gases and each valve is connected to a gear which is rotated by a central common gear which is affixed to a hand wheel adjustment. The regulation of the hand wheel effects a simultaneous proportionate opening and closing of each of the throttle valves. In addition the valves are constructed so that the changes which are produced by one produces a corresponding change of the other so that the overall output flow through the valves is constant.

Method and apparatus for mixing gases under pressure particularly for respirators and medical devices

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Method and apparatus for mixing gases under pressure particularly for respirators and medical devices