Abstract: A controlled force fluid delivery system which provides fluid delivery with continuity over a wide range of flow rate. The system sets the force provided by an energy storage device, e.g. a spring and the opening of system outlet valve in response to a low volume due command. Specifically at a low flow rate, the controlled force is decreased and/or the outlet valve of the system closes before the fluid flow reaches stable velocity whereas at a high flow rate the controlled force is increased and/or the outlet valve does not close until the fluid stops flowing. The system also reduces fluid flow rate variation in part by adjusting the timing and the level of opening and closing the outlet valve, and the speed of pumping the fluid out of system central cassette chamber.

Abstract: A blower supplies compressed air to a predetermined place. The blower is provided with a plurality of compressors, a common air tank for storing compressed air supplied from the compressors, a changeover valve for switching the compressed air taken in from the air tank between a first supply state and a second supply state, and a controller for controlling operations of the compressors and the switching operation of the changeover valve. The controller can select one operation pattern from among a plurality of operation patterns determined by combinations between the compressors and the changeover valve.

Abstract: A reversible pump-turbine system having a discharge adjustment device such as guide vanes, which make it possible to safely stop a pump turbine at the time of emergency shutdown in a generating mode by performing a close operation using an inlet valve even if abnormality has occurred with the guide vanes, without causing abnormal water hammer. Also, at the time of pump mode emergency shutdown, reverse rotation can be prevented even if abnormality occurs in the guide vanes, and it is possible to achieve a safe stop while reducing the loads/stresses to the reversible pump-turbine.

Abstract: Fore many applications it is desirable to determine the operating level, i.e. the current flow rate V and the total pressure difference &Dgr;pt of a fan in the installed state without external measuring points and calibration. The invention should develop a suitable method and a corresponding fan. In the method of the invention, from a measured effective pressure difference &Dgr;pMw a flow rate V is determined and from that, via an operational characteristic curve a target value for the total pressure difference &Dgr;pst is found. By comparing the target value &Dgr;pst determined this way with its measured value &Dgr;pMt the operating level and its accuracy are determined. For this purpose on the fan of the invention measuring points are provided for measuring one or more effective pressure differences &Dgr;pMw and the total pressure difference &Dgr;pMt.

Abstract: A variable volume side branch is provided or attenuating fluid noise in a hydraulic system having a fluid pump and includes a variable volume fluid container having a fluid inlet and a fluid outlet. The fluid container is operable to change the volumetric thereof and to thereby attenuate fluid noise in a hydraulic system in response to changes in fluid pump speed. The fluid inlet of the variable volume fluid container is in fluid communication with a fluid pump and control of the fluid container volumetric is accomplished through the use of a speed sensor, a controller and various actuating mechanisms. The speed sensor determines fluid pump speed and transmits a signal indicative thereof to a controller coupled thereto. The controller is operable to receive an input signal from the speed sensor and to output an appropriate signal to the actuating mechanism to change the volumetric length of the fluid container in response to the input signal.

Abstract: A lift amount of a valve plug is controlled with respect to a period of time from valve-closing operation instruction time for an electric opening/closing valve to arrival at a preset quick valve-closing operation position at which a flow line of a fluid discharged from a discharge port of a nozzle is in a constricted state, in accordance with a driving action of an electric actuator. The valve plug of the electric opening/closing valve is controlled to be at a closed position after the arrival at the quick valve-closing operation position. Accordingly, it is possible to prevent the incontinent liquid drip from the nozzle during the valve-closing operation of the electric opening/closing valve.

Abstract: A control apparatus, for measuring pressure in relation to a rotary screw compressor with capacity control means and a prime mover, including a pressure sensor to monitor the prime mover manifold pressure, and a series of relays which when tripped by the pressure sensor will engage a pressure mechanism to engage the capacity control means on the compressor. The pressure mechanism may be a hydraulic or a pneumatic pressure mechanism and the apparatus may further include a second pressure sensor to monitor the inlet gas pressure to the compressor and a third pressure sensor to monitor discharge pressure of the gas compressor.

Abstract: An air compressor includes a stator, which includes an inlet and an outlet and defines a substantially cylindrical bore, and a rotor eccentrically rotatably mounted in the bore. The rotor is connected to be rotated by a three-phase asynchronous electric motor of pole amplitude modulated type which is switchable between low speed six pole operation and high speed four pole operation under the control of a controller. A pressure sensor communicates with the compressor outlet and is connected to the controller which is arranged to produce a first signal when the compressor discharge pressure falls below a first threshold value and a second signal when this pressure rises above a second threshold value.

Abstract: The present invention concerns a pump provided with a control module and an attachable fluid reservoir cassette. The control module includes a pumping mechanism for pumping fluid from the fluid reservoir to the patient. The cassette is provided with appropriate indicia to identify differences between a plurality of cassettes. The control module further includes cassette indicia identification structure for identifying indicia on the cassette. One type of cassette identification system includes a projection extending from the cassette and structure associated with the control module which engages the projection. Another type of cassette identification system includes a light reflecting system which utilizes light from the control module and reflected off the cassette. Still other types of cassette identification systems utilize other non-contact switches or sensors to sense indicia on the cassette to identify the cassette from a plurality of cassettes.

Abstract: A pump drive head includes a housing, and a main shaft carried on upper and lower bearings disposed in the housing. The main shaft includes an outer torque tube and a liner tube. The outer and liner tubes abut along a first portion of their length and are separated along a second portion of their length forming a double wall with an elongate tubular space in between. A standpipe is coupled at one end to the housing, below the lower bearing, and received by the elongate tubular space an eliminates the need for a lower seal on the main shaft. A hydraulic pump includes a hydraulic pump chamber displosed in the housing and communicating with the main shaft, and first and second gears disposed in the hydraulic pump chamber and the first gear coupled to the main shaft. The second gear intermeshes with the first gear. A suction port is located between the first and second gears and operable when the main shaft is rotated in a reverse direction from the normal pumping direction, during a condition known as backspin.

Abstract: An integral oil filter-pump system for an electric power device which involves a cabinet having an oil-filled compartment for containing the power device, as well as a circulation pump for circulating oil through the system, including the compartment for containing the power device.

Abstract: A booster water pump for increasing source water pressure to a high water pressure for industrial use, has an elongated tubular hollow cylinder having both ends closed with a cylinder inlet port in one end, and a cylinder outlet port to permit the cylinder to be filled with source water. The pump has a submersible motor and hydroturbine pumping unit so articulated that turbine impellers are adjacent the motor and a turbine outlet is away from the motor, the motor-pump unit fitting in the tubular cylinder. The water passageway is annular and the turbine outlet is attached inside the cylinder to the cylinder outlet port. The pump is highly portable and effective to provide high pressure water to remote locations from low pressure sources.

Abstract: An air compressor system having an actuator for controlling the energization of the primary and start windings of the compressor motor and the state of a relief valve is disclosed. No power is applied to either of the windings and said valve is closed when the actuator is disposed in the first position. Movement of the actuator to the second position energizes both of the windings and opens the relief valve so that the motor and compressor can reach full speed before a load is applied. When the actuator is released and moved to the third position, the start winding is deenergized and the relief valve is closed to allow an air storage tank to be filled.

Abstract: First liquid pumping apparatus for containing a first quantity of first liquid, second liquid pumping apparatus for containing a second quantity of second liquid and control apparatus for alternately connecting the first liquid pumping apparatus and second liquid pumping apparatus to pressurized liquid utilization apparatus and for causing the first and second liquid pumping apparatus to alternately deliver the respective liquids to the liquid utilization apparatus at a substantially constant flow or substantially constant pressure; the first and second liquids may be the same liquid or different liquids.

Abstract: A pressure washer is powered by a prime mover, e.g., an electric motor or an internal combustion engine, and has a flow control valve. The valve has a housing containing a piston assembly and the assembly has a mechanism coupled to it for controlling prime mover power. The piston assembly includes a first piston sealing against the housing and dividing the housing interior into two chambers. Such first piston is spring-biased to a first position during periods when no output flow is being demanded from the washer. The assembly also has a second piston spring-biased to seal against the first piston during periods of no flow. When flow is demanded by opening the nozzle, the pressure in the second chamber diminishes. And when the difference between the pressure in the second chamber and that in the first chamber exceeds a predetermined value, the assembly shifts to a second position, causing the mechanism to actuate the prime mover.

Abstract: A system for controlling the pressure output of an engine-driven centrifugal fire pump includes a discharge pressure sensor mounted in the discharge line of the pump. A governor varies the RPM of the engine in response to pressure changes detected by the discharge pressure sensor. An electronically controlled hydraulic relief valve responsive to the discharge pressure sensor operates simultaneously with the governor to provide improved pressure control in overpressure situations.

Abstract: A method for controlling compressor discharge pressure in a compressor. The compressor comprising a compression module driven by a prime mover, the compression module having a discharge port through which a compressed fluid is discharged with a discharge pressure, and an inlet through which uncompressed fluid is flowed into the compression chamber, the flow of fluid through the inlet controlled by an inlet valve repositionable by an actuator driven by a motor. The method comprising the steps of running a discharge pressure control routine, comprising the steps of: calculating the difference between the actual discharge pressure and a predetermined setpoint discharge pressure; computing the required change in valve position to achieve the setpoint discharge pressure, the period of time the motor means must be energized to produce the change in valve position, and the direction the valve must be moved to produce the setpoint discharge pressure.

Abstract: A pumping system for continuously delivering fluid at a selected flow rate to a receiving system. The system includes at least a first and a second pumping unit, each of the individual units comprises a syringe and a valve. The syringe comprises a piston and a piston actuator, cylinder, and pressure sensor. The valve comprises a positively-actuated zero switching volume valve and valve actuator. The first and second pumping units are in fluid communication with one another and are capable of independent actuation. The individual valves are arranged to isolate either the first syringe or the second syringe, respectively, from the receiving system while at least one of the syringes remains in fluid communication with the receiving system whereby system pressure can be continuously monitored and the selected system flow rate maintained.

Abstract: A gas transfer system is provided for establishing or maintaining a predetermined gas pressure within a plenum, such as a tire. In an exemplary embodiment, the gas transfer system includes a power source, a pressure sensor, a control unit, and a gas transfer mechanism. Preferably, a gas transfer mechanism includes a micromechanical device, comprising one or more pumping units that transfer gas from one pressure zone to another. In one embodiment, pumping is accomplished, in part, by heating the gas within a sealable chamber of a pumping unit to cause the pressure of the gas to increase. In another embodiment, the change in pressure of the gas caused by compression of a tire provides a pumping force. Valves are provided for regulating movement of the gas through the gas transfer mechanism and can include electromechanical valves responsive to signals from the control unit, or passively biased valves responsive to applied gas pressure.

Abstract: A fluid control apparatus for use in separation and filtration having a removable sterilizable and disposable element which is engagable with a fixed element in the apparatus. When the two elements are engaged, the flow of fluid around a fluid circuit is controlled to optimize separation. The elements contain various conduits and inlet and outlet ports that function to deliver fluid to and from separation and filtration systems such as life support systems.

Abstract: An assembly is disclosed for supplying compressed air to both an engine and an air suspension of a motor vehicle. The assembly comprises a direct current electric motor, a centrifugal air pump, and a piston pump. The motor has a shaft extending outwardly from opposite sides of the motor, with the centrifugal pump being driven by one end of the shaft and the piston pump being driven by the other end of the shaft. The centrifugal pump produces high volumes of air at low pressure required by the engine, while the piston pump produces low volumes of air at high pressure required by the air suspension. Bypass valves are provided to selectively divert the air provided by the pumps to the atmosphere.

Abstract: A fluid rotating apparatus of a positive displacement pump includes a plurality of rotors accommodated in a housing, a bearing for rotatably supporting the rotors, a suction port and a discharge port formed in the housing, a suction chamber and a discharge chamber in the housing respectively communicating with the suction port and the discharge port, a plurality of motors for individually rotating the rotors, and a detecting device for detecting rotating angles and rotating numbers of the motors. In the apparatus, a fluid is sucked and discharged due to capacity change of a space defined by the rotors and the housing through synchronous control of the rotation of the plurality of motors by a signal from the detecting device. The housing has a communicating path with a flow control device to make an upstream side communicate with a downstream side of the apparatus when the rotational numbers of the rotors are less than a predetermined value.

Abstract: A pumping arrangement including a squeezing device for deforming a length of pliant p.v.c. tubing first in one direction locally to reduce its volume and in another tending to restore its original cross-section and, on either side of squeezing device, inlet and outlet valves which operate by occluding the tubing. The squeezing device and the valves are controlled by a microprocessor control unit such that inlet valve is open and outlet valve shut while the squeezing device is relaxed and thereafter outlet valve is open and inlet valve shut while the squeezing device is operated to deform the tubing, this sequence repeating. Downstream of the output valve is a pressure responsive device providing input to the control unit whereby upon a rise in pressure in the delivery portion of tubing due to a restriction, the squeezing device is disabled and valves are open together to allow excess fluid to pass back towards the fluid source.

Abstract: A well pump system having a motor-driven pump and a pressure tank for delivering water from a source to a utilization point. A sensing device detects a parameter correlated to the rate of flow into and out of the pressure tank. The parameter is utilized to regulate flow into the tank so as to establish at least approximate equality between flow into and out of the tank.

Abstract: In a high-pressure cleaning appliance comprising a high-pressure pump driven by an internal combustion engine, a bypass line leading from the pressure line of the pump to the intake side of the pump and opening when the pressure line is closed, and a pressure sensor in the pressure line, in order to adapt the power of the internal combustion engine to the prevailing operating conditions, it is proposed that the pressure sensor reduce the speed of the internal combustion engine immediately the pressure in the pressure line drops below a certain value.

Abstract: A method for removing floating immiscible liquids from a well containing both the floating immiscible liquids and water, where the floating immiscible liquids and water meet at a water interface, by controlling a cone of depression within the well. A removal system for removing said floating immiscible liquids is used including a microprocessor, a discharge water line and an upper water interface sensor where at least a portion of the discharge water line is located within the well. The upper water interface sensor is located within the well at a sensor location.

Abstract: A vehicle compressor unit having an adjustable outlet pressure at which it will be de-activated. A compressor is operated by an electric motor from the vehicle's electrical supply. A pressure release valve detects the pressure from the outlet of the compressor, the valve being spring loaded and the force on the spring being adjustable to vary and pre-set the pressure which the valve releases. An enclosure into which air releases when the valve releases. Electrical contact means movable by the release of air into the enclosure to de-activate the motor at that pre-selected pressure.

Abstract: A rotary compressor includes first and second compressing devices in a casing to successively carry out a parallel operation wherein first and second compressing devices are parallely driven and a single operation wherein one of first and second compressing devices is driven. A relatively high driving frequency is applied to the rotary compressor during single operation as compared to the driving frequency during parallel operation necessary to produce the same compressing capacity to enhance the EER of the rotary compressor and to extend the variable compressing capacity of the rotary compressor.

Abstract: A method of controlling the air output of a screw compressor, wherein the average air output of the compressor during operation is adapted to air consumption by throttling the flow of suction air or by connecting the compressor alternately to full air output capacity and idle operation capacity. In order to reduce the power consumption of the compressor, the air output is controlled first by throttling the flow of suction air and by simultaneously measuring underpressure in the suction conduit of the compressor. Thereafter the compressor is controlled so as to operate alternately at full air output capacity and idle operation capacity, and the pressure rise rate in the air-pressure network is measured when the compressor operates at full output capacity and the pressure fall rate is measured when the compressor operates at idle operation capacity.

Abstract: In a compressor system, surge detection is provided by sensing the current of the motor driving the compressor and reading oscillations of the current about the average thereof and above and below two opposite threshold levels from such average current and counting the polarity changes within a time interval containing so many samples of the current and defining a sliding window.

Abstract: A method for minimizing the production of sand in submersible-pump well applications is disclosed, in which control of fluid production rates is used to maintain a low rate of change of formation pressure. Simulation of well drawdown conditions in advance of startup allow the prediction of well performance and the selection of a drawdown profile to be implemented in control systems.

Abstract: An apparatus and method are disclosed for an IV pump which can act also as a passive infusion controller. The apparatus has a disposable flow chamber with two pumping subchambers connected by a first collapsible passageway. A pump drive is used to operate the pumping subchambers and includes a first control valve for depressing the first collapsible passageway to control flow between the subchambers and an outlet control valve for depressing an outlet collapsible passageway to control flow of infusate out of the flow chamber. The flow chamber has a base surface and first and second caps, each cap being spaced apart from the base surface and having means for attachment to one of two moveable connector rods. The caps each act as one side of the first and second pumping subchambers, respectively, the base surface being the other side. A flexible wall is connected to the base surface and to each of the caps providing the subchamber volumes therebetween.

Abstract: Infusion liquid flows from a container via a hose controlled by a squeezing valve into a measuring chamber which has an existing predetermined upper filling level and a predetermined lower filling level which may be detected by a filling level detector. A hose pump conveys liquid from the measuring chamber to the patient. In order to adjust the rate of the hose pump in accordance with the provided infusion rate, the time required in case of the closed squeezing valve to pump off fluid from the upper filling level to the lower filling level is determined. Subsequently, the measuring container is refilled within a filling time, while pump is further operative or may be also stopped. The measuring chamber including the hoses connected thereto may be designed as a disposable unit.

Abstract: A compressed air supply system including an electric motor for driving an air compressor. An air reservoir connected to an outlet of the air compressor via a cooler. A dryer and a check valve, a pressure sensor coupled to the air reservoir for sensing the pressure therein. An unloading valve coupled to the outlet of the air compressor. A control circuit coupled to the electric motor and the unloading valve. A protective circuit coupled to the control circuit and the unloading valve for preventing the motor from starting under an overload condition and for averting the unnecessary running of the motor and driving of the air compressor.

Abstract: A control apparatus and method for restricting liquid flow in a liquid moving pump, usually of the centrifugal type, to prevent pump cavitation and pump prime mover overloading. The control apparatus includes sensors to detect liquid temperature and pressure at the inlet of the pump. It may further include a device such as a current transformer to develop a signal indicative of power consumed by the prime mover of the pump where the prime mover is an electrical motor. The liquid pressure and temperature indications are used to generate a specific indication of the subcooling of the liquid. The temperature indication is used to derive an indication of the instantaneous required subcooling of the pump. The subcooling indication and the required subcooling indication are introduced to a comparator. Should the subcooling of the liquid fail to exceed the required subcooling, a first control signal is generated.

Abstract: A surge control fluid delivery system is described particularly adapted for pumping of high-viscosity substances from a reservoir for dispensing. The system includes a manifold which is connected to an outlet line of a pump. A vent circuit for returning fluid from the manifold to the reservoir is also provided. Surge control is achieved through a control system which modulates the fluid supply pump and further activates a valve in the vent return line to maintain the pressure of the fluid within the manifold to within adjustable upper and lower limits. The system further includes means for automatically switching from one source of fluid to another upon depletion of the first source.

Abstract: A method and apparatus for regulating power consumption while controlling surge in a centrifugal compressor are disclosed. Various operating parameters of a centrifugal compressor are measured and based upon these parameters control of the power consumption of the compressor motor via inlet guide vanes and/or diffuser vanes is achieved. Additionally, the control senses and regulates power consumption and vane positioning to control operation under surge conditions and will, if necessary, energize a blow-off valve to prevent operation under surge conditions. The control is designed to integrate compressor and motive source operation to effectively minimize power consumption while avoiding operation in the surge range.

Abstract: The pump-off controller checks for pump-off by calculating the area inside of a figure whose boundaries are the minimum load, two position lines defined by the user and the load at the time the calculation is being made. This area is compared to a user defined limit to determine whether pump-off has occurred. While the well is running the controller also checks the value of the minimum load, and if it is outside of preset boundaries it readjusts the load signal to locate it within the desired range. The position synthesizer cyclically detects the position of the beam or rod during each stroke and generates a waveform whose amplitude and frequency correspond to the motion of the rod with a period corresponding to the time of each stroke. This information is used by the controller to determine the top of the stroke and to check for pump-off.

Abstract: A pressure controller includes a set point switch mechanism by which a selectable pressure to be maintained in a pressure vessel can be set. The actual pressure in the pressure vessel is detected and converted into a corresponding electrical signal by a suitable pressure transducer. Electrical signals from the set point switch mechanism and the transducer are utilized by a computer to generate control signals for controlling a volume adjustment mechanism which adjusts the effective volume of the pressure vessel and adjusts the quantity of pressurizing fluid disposed in the vessel. The volume adjustment mechanism includes a piston disposed in a cavity which is connectable with the chamber of the pressure vessel. The volume adjustment mechanism also includes a stepper motor which can be moved in precise increments to adjust the position of the piston in the cavity.

Abstract: Regulator in a motor driven pump for the regulation of the output pressure according to a predetermined value. An automatically functioning reliable regulation according to a predetermined value in order to impede cavitation and reduce the risk of an interrupted flow of liquid in the pump is provided by means of the invention. This is made possible by means of a double diaphragm (12) via a preferably spring biased transmission means (4, 10) of movement being in connection with a controlling means serving the purpose to control the capacity of the power source of the pump and with a space (27) between the diaphragm elements (12A, 12B) of said double diaphragm (12) being connected with the output pressure (30) from the pump for the actuation of the double diaphragm (12) in order to adjust the controlling means of the capacity in a desired degree, and increased or decreased fluid output from the pump bringing about a displacement of the double diaphragm (12) to its maximum position (FIG.

Abstract: The invention relates to an air intake regulator for a compressor. The pressure in an oil separator is sent into the rear chamber of a jack having a membrane, which controls the acceleration or the slowing of a motor driving a compressor. A front chamber is placed under compression by the intake of the compressor. A selectively operable valve selectively interrupts the flow of air drawn in through an air filter.

Abstract: A method of controlling a motive power and fluid driving system according to the present invention is disclosed, which generally comprises the steps of sensing a plurality of operating parameters and at least one control parameter defining the energy quotient for the motive power and fluid driving system, and adjusting the control parameter(s) to substantially maximize the energy quotient for the system. The control method may also include the step of substantially maximizing the energy quotient at a predetermined or desired capacity of fluid flow.

Abstract: A control valve and switch assembly for automatic control of the pressure in a high pressure fluid system, such as in car washing apparatus, and comprising a housing having a fluid chamber therein providing communication between a pressure fluid source, such as a pump, and a fluid discharge valve, such as a spray nozzle, a fluid outlet passage provided in the housing in communication with the pressure chamber; a primary pressure switch secured to the housing and open to the pressure within the pressure chamber for selective opening and closing; the primary pressure switch being operably connected between a power supply and a motor starter for selective activation of the motor starter; an unloader valve in communication with the outlet passage and responsive to the pressure therein for selective opening to bleed excessive pressure from the pressure chamber to a fluid return line, and a secondary pressure switch secured to the housing and open to the return pressure; the secondary pressure switch being operably

Abstract: An apparatus having latching effect for limiting pressure in liquid feeding systems has a valve means inserted in the feeding path of a pump supplied liquid. The valve means includes a shunt valve opened upon excessive output pressure; the shunt output of the shunt valve is connected to a feed-back tube. There is further provided a back-stroke valve in the main feeding path of the liquid. A first pressure switch has the output pressure applied thereto while to a second pressure switch the input pressure at the shunt valve is applied. The two pressure switches are inserted into the switch-on circuit of the pump in such a manner that the pump is switched-on in the presence of a low output pressure and switched-off in the presence of an excessive output pressure.

Abstract: A switch device for an air compressor plant including an air receiver, an air compressor having an unloader valve mechanism, an electrical motor for driving the compressor, and an electrical supply circuit including a main line for energizing the motor and a pair of capacitor circuits, comprising a pneumatically actuated air valve in an air line between the air receiver and the unloader valve mechanism, in which the air valve is adapted to be opened when excessive pressure is developed in the air receiver for supplying air through an unloader control line to the unloader mechanism. Also, included in the unloader air line is a pneumatic switch actuator device adapted to automatically and simultaneously open switches in the main supply line circuit and the capacitor circuits when the air valve is open.

Abstract: A method and system for controlling natural gas compressor and engine units. Particularly, the control method provides for the adjustment of the engine speed and compressor loading, so as to minimize the compressing energy required while maintaining a desired gas flow through the pipeline. The control of the engine speed and compressor loading is based in part on an energy quotient value for the unit. The control method further provides for efficient operation during multiple-stage compression, by controlling the interstage pressure. The control method is also adapted to predict impending compressor and engine unit failures. The control system is based upon a digital-type controller which generates control signals in response to changes in the energy quotient value for the unit.

Abstract: In a process in which a turbo-expander is utilized to drive a compressor, the pressure of the gas flowing to the turbo-expander is maintained at a desired level by manipulating the speed of the turbo-expander. If the turbo-expander should tend to overspeed, the discharge output of the compressor is recycled to the suction inlet of the compressor to thereby increase the loading on the compressor which will result in a reduced turbine speed. More gas can then be fed through the turbo-expander which will maintain the desired pressure. If the pressure of the gas flowing to the turbo-expander should continue to increase, a bypass valve is utilized to bypass the turbo-expander to thereby maintain a desired pressure of the gas flowing to the turbo-expander.

Abstract: A waste gas recovery system employs a compressor which takes in waste gas from an inlet knock-out drum and passes compressed gas to a heat exchanger which cools the gas prior to passage through a further outlet knockout drum. The compressor is driven at a speed which is selected in accordance with the sensed pressure of the incoming waste gas and a valve progressively controls the supply of gas to the compressor inlet in accordance with the sensed pressure. Liquid condensate from the knock-out drums collects in a header tank. A temperature sensing and control arrangement injects liquid from this tank at the inlet to the compressor in the event of an excessive temperature rise at the outlet of the compressor. Gas is also re-circulated from the output of the system to the compressor inlet should the injection of liquid be insufficient to reduce the temperature rise.

Abstract: A waste gas recovery system employs a compressor which takes in raw waste gas from an inlet knock-out drum and passes compressed gas through a heat exchanger to an outlet knock-out drum. The temperature at the outlet of the compressor is sensed by a device which operates valves to inject liquid coolant into the compressor inlet and to re-circulate gas back from the outlet of the outlet knock-out drum to inhibit an excessive temperature rise. A pressure-sensing device senses the pressure of the gas passing into the compressor and controls both the speed of the compressor and an adjustable throttle valve to regulate the gas flow. The throttle valve is closed automatically should there be a fall in the pressure of the gas at the inlet below a safe level. In this event, further pressure-sensing devices act additionally to close the recirculating gas valve and a further valve in the main inlet flow path to reliably isolate the compressor.

Abstract: A method and apparatus for controlling a compressor is disclosed wherein both the compressed air output and the speed of the compressor are simultaneously adjusted in relation to compressed air demand over a wide range of air demands and in a way so as to use less input energy during below-peak demand and automatically return the compressor to an operating condition of minimum speed and minimum power input when there is no demand on the compressor. A reciprocating piston compressor with at least two, and typically more than two, compression chambers driven by a prime mover has a separate unloader device for each compression chamber. A control assembly is responsive to tank pressures indicating demand on the compressor with the movement of one movable control member simultaneously operating both a control valve adapted for successively operating each of the unloader devices one at a time and a speed regulating member for the prime mover.