Abstract: An external fluid circuit capable of being connected between service valves provided on a closed system containing a refrigerant. The external fluid circuit is provided with a testing tube and testing tube holder. A flow meter and flow regulator are connected in series in the external fluid circuit. The flow meter is provided with a transparent chamber containing a float indicator member to indicate when a desired rate of refrigerant flow through the circuit has been achieved. A three-way toggle valve is provided between the flow meter and testing tube holder allowing the refrigerant to be directed through the testing tube or through a bypass loop. A hand-held compressor downstream of the testing tube holder induces sufficient flow pressure difference where there is insufficient system pressure to cause proper flow through the external fluid circuit.

Abstract: Provision is made in a refrigeration purge system for sensing certain conditions indicative of failure of components within the system, to responsively shut-down the system and prevent refrigerant from being undesirably vented to the atmosphere. Failure conditions sensed include inadequate cooling medium to the condenser coil and failure of a relief valve.

Abstract: In order to enhance the efficiency of removing refrigerant from the mixture of non-condensable gases in a purge recovery system, a carbon filter is placed in the flow of mixed gases from the purge chamber such that any remaining refrigerant can be absorbed by the filter and not be vented to the atmosphere with the non-condensable gases. The filter is periodically reactivated by the operation of a vacuum pump to remove the refrigerant from the carbon filter and return it to the system refrigeration circuit. The reactivation process is initiated and controlled by way of a pressure switch and a timer.

Abstract: In a centrifugal machine for a refrigeration or air conditioning system and including a casing, an impeller, a variable width diffuser assembly leading from the impeller, and a plurality of vanes received through respective complementary-shaped openings in a movable wall member, there is provided a sealing means in the openings between the vanes and movable wall member for preventing leakage of fluid through the openings, thereby increasing the operating efficiency of the machine.

Abstract: A method and control system are disclosed for minimizing the number of recycle starts of a compressor in a refrigeration system to thereby reduce wear and tear on the mechanical and electrical systems of the refrigeration system thereby prolonging the operating life and improving the reliability of the refrigeration system. The rate at which the refrigeration system compressor's capacity is increased upon the recycle start is greatly reduced compared to a normal, relatively fast rate of increase which is provided when the capacity of the compressor is controlled directly in response to the load placed on the refrigeration system. This prevents the refrigeration system from quickly satisfying a new, increased load placed on the refrigeration system upon a recycle start which will then require a relatively quick shutdown of the refrigeration system compressor due to excess cooling capacity and require a relatively quick subsequent recycle start of the compressor.

Abstract: A method and control system are disclosed for minimizing the number of recycle starts of a compressor in a refrigeration system to thereby reduce wear and tear on the mechanical and electrical systems of the refrigeration system thereby prolonging the operating life and improving the reliability of the refrigeration system. By limiting the load placed on the refrigeration system upon a recycle start the rate at which the refrigeration system satisfies the load is significantly reduced compared to a normal, relatively fast rate of satisfying the actual load which usually occurs when the capacity of the compressor is controlled directly in response to the actual load placed on the refrigeration system.

Abstract: A method and control system are disclosed for checking and verifying sensor operation in a refrigeration system. A microcomputer control system determines whether a signal provided by the sensor is within normal limits prior to startup of the refrigeration system. Also, the microcomputer system verifies an out of bounds sensor signal provided to the microcomputer system from the sensor during operation of the refrigeration system by intermittently monitoring the sensor to determine whether a preselected consecutive number of out of bounds signals are provided to the microcomputer control system from the sensor.

Abstract: A method and control system for protecting an electric motor driven compressor in a refrigeration system are disclosed. The refrigeration system operates to satisfy a load placed on the system and the refrigeration system compressor is turned off when the load is satisfied and the refrigeration system is providing excess capacity. When the compressor is turned off due to excess capacity, current flow to the electric motor driving the compressor is sensed and the refrigeration system is shut down if the sensed current flow is abnormal. In this manner, the compressor and the electric motor driving the compressor are protected against restarting under unfavorable operating conditions which could unduly wear the compressor motor and/or the compressor.

Abstract: A centrifugal compressor having a variable wall diffuser section that is controlled in response to measured system parameters in order to maintain the compressor at optimum efficiency over extended operating range.

Abstract: A method of regulating startup operation of a vapor compression refrigeration system to prevent oil pump cavitation during startup of the refrigeration system is disclosed. The method comprises monitoring the rate of decrease in evaporator pressure or temperature or monitoring compressor suction line pressure and then comparing this monitored rate to a rate of pressure or temperature decrease which is predetermined to prevent oil pump cavitation. If the monitored rate exceeds the predetermined rate control action is taken to adjust the capacity of the compressor to provide a desired rate of pressure drop which prevents oil pump cavitation. A microprocessor control system and a mechanical control system are disclosed for carrying out the disclosed method.

Abstract: A method and control system for operating a vapor compression refrigeration system to prevent oil pump cavitation during startup of the refrigeration system is disclosed. The control system includes a temperature or pressure sensor located in the evaporator of the refrigeration system, a microprocessor, and an inlet guide vane control mechanism. During startup, the pressure of the gaseous refrigerant or the temperature of the liquid refrigerant in the evaporator of the refrigeration system, or compressor suction line pressure, is measured and an electrical signal corresponding to the measured pressure or temperature is processed by the microprocessor to determine the actual rate of pulldown of refrigerant pressure in the evaporator. The microprocessor compares the actual pulldown rate to a pulldown rate which has been predetermined to prevent compressor oil pump cavitation.

Abstract: In a centrifugal gas compressor the capacity and the prewhirl of the entering gas are both controlled by reciprocating a plug which is located in the flow path. The plug coacts with tapering walls of the flow path to vary the minimum cross-sectional area of the flow path. Additionally vanes are provided either in the wall of the flow path or on the plug. The vanes transition from an axial direction to a helical direction and of reducing height in a downstream direction so as to produce increasing prewhirl with decreasing capacity. Alternatively, prewhirl may be provided without capacity control.

Abstract: A diffuser control for controlling vapor flow through a diffuser passage comprising an annular recess defined by a housing of the diffuser passage and in communication therewith, and an annular control ring supported for movement within the recess and the diffuser passage between a throttling position, wherein the restriction means throttles vapor flow through the diffuser passage, and an open position for permitting a substantially free flow of vapor through the diffuser passage. The diffuser control further comprises a plurality of springs supported by the housing for urging the control ring toward the throttling position, a stop for limiting movement of the control ring at the throttling position, a low pressure conduit for connecting the annular recess to a low pressure source, and a seal for retarding vapor flow from a higher pressure side of the control ring to a lower pressure side thereof when the control ring is in the open position.

Abstract: Motor cooling system for refrigeration machine wherein one condenser connected to a main stage of the compressor is used to satisfy the cooling requirements of the system and a second condenser connected to a subsequent higher pressure compressor stage is employed for heating a medium to satisfy heating requirements of the system. The motor cooling system contains a three-way selector valve which connects either condenser selectively to the motor housing in response to the pressure in one condenser exceeding the pressure in the other condenser to provide a sufficient liquid refrigerant to the motor for cooling motor components under all operating conditions. The selector valve comprises a horizontally extending tubular portion having an annular seat at each end of the portion and a vertically extending tubular portion attached thereon.

Abstract: A diffuser control for controlling vapor flow through a diffuser passage comprising an annular recess defined by a housing of the passage and in communication therewith, a diffuser control ring supported for movement within the annular recess and the diffuser passage between a full throttling position, wherein the restriction means throttles vapor flow through the diffuser passage, and an open position for permitting a substantially free flow of vapor through the diffuser passage. The control further comprises a first set of springs for urging the control ring toward the full throttling position, and a second set of springs for urging the control ring toward an intermediate throttling position located between the open and full throttling positions. The diffuser control also comprises a low pressure conduit for connecting the annular recess to a low pressure source, and a intermediate pressure conduit for connecting the annular recess to an intermediate pressure source.