Abstract: Systems and methods for reducing the pressure of a first pressurized fluid, thereby reducing the temperature of the pressurized fluid, and utilization of the reduced-pressure and temperature fluid to cool a second fluid. Such an approach can enable a reduction in the size and weight of a hydraulic system, utilize waste energy in a system, and/or minimize electrical power requirements of a system, among other benefits.

Abstract: Method and system for determining the real-time flow into a wastewater pump station using analog level sensing technologies. An Accurate Level Generator mechanism supplies an accurate mean value out of multiple readings for each level used to calculate the volume between levels. Two consecutive levels are used to calculate the volume between them using an Accurate Flow Calculator and the time it took to get from one level to the other. A Real Time Inflow Calculator adds results regarding the pumps in operation and overflow events, which are ways for the water to exit the pumping station. At a water level approaching where the pumps start or stop, or when abnormal events occur, a Predictive Abnormal Event Adjuster replaces the highly probable abnormal Real Time Inflow Result by a more stable and possible value, which is the last one calculated plus its variation over time.

Abstract: A refuelling device for supplying liquefied gas is provided, including a feed system adapted to place each reservoir in fluidic through connection with a tank and including withdrawal ducts for withdrawing the liquefied gas from the reservoirs; an inlet duct for introducing the liquefied gas into the tank; a collection manifold for conveying the withdrawal ducts into the inlet duct; a pump adapted to move the liquefied gas in the feed system; and a pressure gauge to measure the inlet pressure of the liquefied gas in the pump; and a valve adapted to regulate the flow in the inlet duct according to the inlet pressure.

Abstract: Systems and methods for reducing the pressure of a first pressurized fluid, thereby reducing the temperature of the pressurized fluid, and utilization of the reduced-pressure and temperature fluid to cool a second fluid. Such an approach can enable a reduction in the size and weight of a hydraulic system, utilize waste energy in a system, and/or minimize electrical power requirements of a system, among other benefits.

Abstract: A pressure boosting system and a method of using the same to increase fluid pressure in a fluid distribution system are disclosed. The pressure boosting system may be installed “in-line” with the fluid distribution system.

Abstract: A motor control device which controls a motor for driving a blower unit, comprises: a target motor output calculating section which calculates a target motor output which causes an air flow of air supplied from the blower unit to coincide with a target air flow; and an operation command generating section which obtains the motor output of the motor, and generates a command for controlling a physical amount of the motor such that the motor output coincides with the target motor output based on a result of comparison between the motor output and the target motor output; and the target motor output calculating section is configured to calculate the target motor output as a product of a polynomial of variables derived by dividing the target air flow by the motor speed, and a cube of the motor speed.

Abstract: A blood circuit having a pressure measurement portion connected to a pressure measurement device includes: a first measurement portion provided downstream of a pumping segment; and a second measurement portion provided upstream of the pumping segment. The first measurement portion includes: a first housing having a tubular shape; and a first flexible membrane having a tubular shape and provided in the first housing. The second measurement portion includes: a second housing having a tubular shape; and a second flexible membrane having a tubular shape and provided in the second housing. A space between the first flexible membrane and the first housing is larger than a space between the second flexible membrane and the second housing in an initial state before permitting the blood to flow.

Abstract: Systems and methods for reducing the pressure of a first pressurized fluid, thereby reducing the temperature of the pressurized fluid, and utilization of the reduced-pressure and temperature fluid to cool a second fluid. Such an approach can enable a reduction in the size and weight of a hydraulic system, utilize waste energy in a system, and/or minimize electrical power requirements of a system, among other benefits.

Abstract: The present invention relates to a method for controlling a pump, in particular a centrifugal pump, during pumping of a liquid, comprising the following steps: fixing a setpoint value of a flow rate of the pump; measuring an inlet pressure of the liquid upstream of the pump and an outlet pressure of the liquid downstream of the pump; determining a setpoint value of a rotational speed of the pump from a performance map of the pump, wherein the fixed setpoint value of the flow rate and a difference between the outlet pressure and the inlet pressure are incorporated into the performance map as input values; and setting the rotational speed of the pump to the setpoint value of the rotational speed. Furthermore, the invention relates to a corresponding device for controlling a pump.

Abstract: Automated operation of well site pumping equipment, including generating a mathematical belief model for maintaining an interrelationship between flow rate achievable by a pump unit discharge pressure of the pump unit, and probability of achieving the flow rate at corresponding discharge pressure. Speed of the pump unit is controlled to achieve a target speed based on a flow rate set-point and the mathematical belief model and updating the mathematical belief model at least while the target speed is achieved. Updating the mathematical belief model may include increasing the probability of achieving the flow rate set-point when actual flow rate of the pump unit is not less than the flow rate set-point and decreasing the probability of achieving the flow rate set-point when the actual flow rate of the pump unit is less than the flow rate set-point.

Abstract: A pressure boosting system and a method of using the same to increase fluid pressure in a fluid distribution system are disclosed. The pressure boosting system may be installed “in-line” with the fluid distribution system. The pressure boosting system includes a submersible pump and a controller that may be configured to control the submersible pump based on an outlet pressure if inlet pressure is below a threshold. The pressure boosting system may also control the submersible pump based on a flow of the fluid through a pump unit as a function of the inlet pressure. A mounting bracket may be moveably coupled to a tank of the pressure boosting system.

Abstract: A method for determining a through-flow quantity in a fluid delivery system, in which a fluid is delivered by a pump, the pump including an electromotor and the electromotor being operated at a first speed when the electromotor is in operation and the through-flow quantity being determined from a measured motor power and the speed. The method includes (i) increasing the first speed to a second speed which is greater than the first speed; (ii) determining a second through-flow quantity at the second speed from the motor power and the second speed; (iii) determining a third through-flow quantity from the second through-flow quantity by extrapolation of the second speed to the first speed, wherein the third through-flow quantity is the target variable; and, (iv) reducing the speed back to the first speed once the second through-flow quantity has been determined.

Abstract: A fluid transport system includes at least one flow control device and a multiphase pump configured to transport fluid. At least one pump sensing device is configured to measure at least one operating characteristic of the multiphase pump. A controller is programmed with a pump map including a correlation of the at least one operating characteristic of the multiphase pump with at least one operating characteristic of the fluid. The controller is configured to determine an estimated value of the at least one operating characteristic of the fluid based on the measured value of the at least one operating characteristic of the multiphase pump and the pump map. At least one regulating device coupled to at least one flow control device is modulated based on the estimated value of the at least one operating characteristic of the fluid.

Abstract: A method of controlling the production efficiency of a well includes determining one or more parameters of a pump model for a pump of the well, determining an inflow rate of liquid into the well, and adjusting a pumping speed of the pump based on the one or more parameters of the pump model to maintain a outflow rate of liquid from the well at a desired fraction of the inflow rate.

Abstract: A pressure detection device of a liquid flow route includes; displacement detecting means that detects displacement of a peristaltically-actuated tube in the radial direction; pressure calculating means that is able to calculate blood removal pressure based on the displacement of the peristaltically-actuated tube; closed flow route forming means that is able to form a closed flow route which includes a portion at which the displacement detecting means is disposed; pressure changing means that is able to arbitrarily change the pressure in the closed flow route; pressure detection means that is able to detect pressure change in the closed flow route; and calibration curve acquiring means that is able to produce and acquire a calibration curve with which the displacement detecting means and the pressure calculating means are calibrated by a relationship between the pressure change detected by the pressure detection means and a detection value of the displacement detecting means.

Abstract: An automated seed treatment system is adapted for on-site operation at a retail seed distributor. A sealed seed-treater vessel is configured to apply a plurality of chemical treatments to a batch of seed based on a recipe. A programmable system controller is electrically coupled to pump controllers of pump-stations. The controller is configured to receive a material transfer indication from each pump-stations and control the pump controllers in accord with the seed treatment recipe. The programmable system controller is configured to collect operational data representing at least consumption of chemical from the chemical container at each of the pump-stations based on the corresponding material transfer indication during seed treatment and to provide the operational data to a remotely hosted information system located remotely from the site of the retail seed distributor and accessible to at least one third party that is distinct from the retail seed distributor.

Abstract: A pumping system for at least one aquatic application comprises a motor coupled to a pump and a controller in communication with the motor. The controller may be adapted to determine a first motor speed, determine a present flow rate using curves of speed versus flow rate for discrete power consumptions, generate a difference value between the present flow rate and a reference flow rate, and/or drive the motor at a second motor speed based on the difference value until reaching a steady state condition.

Abstract: Methods and systems for controlling a chiller system to achieve control stability while maintaining optimum efficiency. Particularly, methods and systems for controlling a centrifugal compressor speed and an inlet guide vane position that establishes three distinct regions in the control path: (i) during initial unloading from full load, the inlet guide vane position is kept at a fully open position while the centrifugal compressor speed is changed to achieve the desired cooling capacity; (ii) between an inflection point and a transition point, keeping the centrifugal compressor speed constant while the inlet guide vane position is changed to achieve the desired cooling capacity; and (iii) between the transition point and zero cooling capacity, changing both the inlet guide vane position and the centrifugal compressor speed to achieve the desired cooling capacity.

Abstract: An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Abstract: The embodiments herein disclose a method and system for measuring and controlling an amount of flow and volume of liquid/fluid and/or electrical energy. The method and system obtains a plurality of values for the electrical parameters of an electro-pump, including voltage value, current value and active/reactive energy value; calculates the plurality values; and determines and controls the amount of instant flow and volume of the liquid/fluid based on the calculated values. The system/method gathers these two measuring and controlling features such as measuring and controlling the volume of liquid and amount of energy in one casing, thereby providing a secure reference for both the parameters at the same time for underground water resources.

Abstract: The present disclosure relates to a multiple-capacity centrifugal compressor, which includes a plurality of capacity-control mechanisms. Each of the capacity-control mechanisms includes an inlet guide vane and an outlet diffuser, so that the multiple-capacity centrifugal compressor provides a flexible control strategy. In addition, the present disclosure further provides a method for controlling the multiple-capacity centrifugal compressor that effectively adjusts and controls the capacity-control mechanisms by coarsely adjusting the inlet guide vanes and combined with subsequently adjusting the outlet diffusers.

Abstract: A pressurization control system configured to regulate air pressure within a space includes a first damper fluidly coupled to an air supply, the first damper configured to control delivery of an air flow, and a second damper having an operating range, the second damper fluidly coupled to the air supply and the first damper, the second damper configured to supplement delivery of the air flow. The pressurization control system further includes a room controller configured to provide a control signal to the first and second dampers, wherein the control signal drives the first damper to direct the air flow towards the operating range, and wherein the control signal drives the second damper to direct the air flow towards a set point.

Abstract: A method and apparatus for producing and controlling flow rate of a compressed gas produced by a compression system having one or more stages of compression formed by a centrifugal compressor or compressors, inlet guide vanes to control flow through the compression stage or stages and an electric motor directly coupled to the stage or stages having a restricted speed zone within which vibrational modes can damage the electric motor. A desired flow rate is obtained by speed adjustment alone and with the inlet guide vanes positioned at 0° when the speed will lie above or below the restricted speed zone. Where a desired flow rate would require extended operation of the electric motor at a speed within the restricted speed zone, the speed is set to the uppermost level of the restricted speed zone and the desired flow rate is obtained through appropriate positioning of the inlet guide vanes.

Abstract: An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Abstract: There is provided a centrifugal compressor apparatus including a centrifugal compressor that centrifugally compresses a gas, an electric motor that rotatably drives the centrifugal compressor, a current detector that detects a drive current I of the electric motor, and an exhaust valve that discharges a compressed gas to a lower pressure section. The centrifugal compressor apparatus (A) detects the drive current I at a sampling cycle ts, (B) updates, as a current threshold, in real time, a value “(moving average)?n×(standard deviation)” for which a plurality of drive currents measured in a sampling period tp serves as a population, where n is a positive number in the range of 3 to 4 and, (C) determines that surging has occurred when the exhaust valve is closed and the drive current I is below the current threshold X, and (D) further opens the exhaust valve to discharge the compressed gas when determining that surging has occurred.

Abstract: An electromagnetic valve, which is provided between an intake port of a compressor body and a pneumatic line at an intermediate position of an intake pipe, is opened/closed by a control unit. Communication between the intake port of the compressor body and the pneumatic line is permitted when the valve is open, and is blocked when the valve is closed. In a start-up control of the compressor body, the electromagnetic valve is opened, permitting communication of the pneumatic line in the plant with the intake port of the compressor body for power supply to an electric motor to drive an orbiting scroll. Rattling of the orbiting scroll by an amount equal to the axial gap (play) is suppressed before starting a compression operation.

Abstract: A water supply apparatus is configured to meet energy-saving demands by controlling a pump so that the rotational speed of the pump is lowered while keeping a constant flow rate. The water supply apparatus includes a pump for pressurizing and delivering water, a frequency converter for supplying electric power to the pump to operate the pump at a variable rotational speed, a discharge-side pressure sensor for detecting a pressure at a discharge side of the pump, and a controller (15) for controlling the rotational speed of the pump. The controller (15) stores a plurality of control head curves (B, C1, C2, C3) representing different relationships between flow rates (Q) and heads (H), and controls the rotational speed of the pump based on an alternatively selected one of the control head curves (B, C1, C2, C3).

Abstract: An improved pump, reservoir and reservoir piston are provided for controlled delivery of fluids. A motor is operably coupled to a drive member, such as a drive screw, which is adapted to advance a plunger slide in response to operation of the motor. The plunger slide is removably coupled to the piston. A method, system, and an article of manufacture for automatically detecting an occlusion in a medication infusion pump is provided. The electrical current to an infusion pump is measured. Based on a series of measurements of one or more variables, the infusion pump detects whether there is an occlusion in the system.

Abstract: The present invention relates to a method and control system to control the speed of a centrifugal compressor operating within a vacuum pressure swing adsorption process to avoid an operation at which surge can occur and directly driven by an electric motor that is in turn controlled by a variable frequency drive. In accordance with present invention an optimal speed for operation of the compressor is determined at which the compressor will operate along a peak efficiency operating line of a compressor map thereof. This speed is adjusted by a feed back speed multiplier when the flow or other parameter referable to flow through the compressor is below a minimum and a feed forward multiplier during evacuation and evacuation with purge steps that multiplies the feed back multiplier to increase speed of the compressor and thereby avoid surge.

Abstract: A system and a method for operating a variable-displacement compressor are provided wherein a volume of a compression chamber of at least one cylinder is varied during a compression cycle, wherein during the cycle the at least one cylinder is alternately coupled to a low pressure side and a high pressure side of the compressor. A first thermodynamic state of the low pressure side and a second thermodynamic state of the high pressure side can be estimated and a current compression ratio ( v in v out ) of the compressor can be estimated. Accordingly, a compressor displacement (D) as a function of the compression ratio ( v in v out ) can be calculated. From this, a compressor torque (M) depending on the calculated displacement (D) can be computed, and the compressor torque (M) can be provided to a control unit for operating the compressor or an engine coupled to the compressor.

Abstract: A vehicle includes a clutch set, a tank with fluid, an auxiliary battery, an electric fuel pump, and a controller. The electric fluid pump delivers some of the fluid from the tank to a designated oncoming clutch of the clutch set. The controller calculates a predicted flow value for the oncoming clutch during the shift event, and selectively controls the speed of the pump using the predicted flow value during the shift event. The controller controls the pump using an actual flow value when the vehicle is not executing a shift event, i.e., when holding torque. The speed of the electric fluid pump is increased to a first calculated speed determined using the predicted flow value when the shift event is initiated and before filling of the oncoming clutch commences, and is reduced to a second calculated speed determined using the actual flow value when the shift event is complete.

Abstract: An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Abstract: A system for measuring current in an H-Bridge motor drive circuit and using that current to determine the output of a device powered by the motor. A particular embodiment is disclosed for a motor-driven fluid pump. Motor current is measured at predetermined pump pressures and flow rates to create calibration tables relating motor current to pump pressure. Once calibrated, the system determines pump pressure based on motor current by referring to the calibration tables. In an embodiment, the pump is driven to achieve a predetermined fluid dispense profile. The system monitors pump pressure by measuring motor current and determines if the dispense profile is being achieved and sets alarms if predetermined thresholds are not maintained. The system also detects pump wear based on the current measurements and issues warnings to the user in such conditions.

Abstract: A fire truck operable to automatically refill a water tank comprises a first pressure transducer coupled to an intake inlet of the pump and operable to measure an intake pressure, a second pressure transducer coupled to a discharge outlet of the pump and operable to measure a discharge pressure, a first pump discharge pipe coupled between the discharge outlet of the pump and a fire hose, a second pump discharge pipe coupled between the discharge outlet of the pump and the water tank, a control valve disposed in the second pump discharge pipe, and a controller operable to automatically sense a low water level condition of the tank, and automatically control the engine speed, the pump speed, and the control valve so that adequate water supply to the fire hose via the first pump discharge pipe is automatically maintained while automatically refilling the water tank via the second pump discharge pipe.

Abstract: An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Abstract: A method for controlling the motor of an air handling system to provide a desired output of flowing air therefrom while minimizing the power used by the motor, including operationally connecting a switched reluctance electric motor to a blower, operationally connecting an electronic controller to the switched reluctance electric motor, operationally connecting at least one sensor to the electronic controller, measuring at least one environmental parameter with the at least one sensor, inputting the desired air flow into the electronic controller, calculating the minimum motor speed necessary to provide the desired air flow, and sending a control signal from the electronic controller to the motor to control the motor to the minimum motor speed necessary to provide the desired air flow.

Abstract: A method of operating a multistage gas compressor system including providing a plurality of compressor stages connected in series, receiving a gas flow having contaminants within a gas passage, and supplying solvent to the gas passage at or upstream of a compressor in a compressor stage of the plurality of compressor stages to entrap or dissolve the contaminants in the gas flow. The method includes resisting disabling fouling of the compressor in the compressor stage from any contaminants entrapped or dissolved in the solvent, for example, by controlling a discharge temperature of the compressor, and/or using a type of compressor that is not susceptible to being disabled by fouling in at least the first stage. The discharge temperature can be controlled by providing the compressor with a pressure ratio selected to provide a desired discharge temperature.

Abstract: One form of a hydrogen operated power system according to this invention is a fuel cell system (20) provided with a supply system which supplies a gaseous fuel from a fuel supply tank (24) to a fuel cell (22), characterized in that a pump (32) is provided in the supply system, which is driven by a sensorless motor (34) having no sensor that detects at least a rotational position of the motor (34).

Abstract: A system for controlling a centrifugal gas compressor (108) in an HVAC, refrigeration or liquid chiller system (100) in which flow of gas through the compressor is automatically controlled to maintain desired parameters within predetermined ranges so as to prevent stall and surge conditions within the system. A variable geometry diffuser (119) in the compressor controls the refrigerant gas flow at the discharge of the compressor impeller wheel (201). This arrangement reduces mass flow, decrease/eliminate flow-reducing stall, and increases the operating efficiency of the compressor at partial load conditions. The variable geometry diffuser control in combination with a variable speed drive (VSD) (120) increases the efficiency of the compressor at partial system loads, and eliminates the need for pre-rotation vanes at the inlet of the centrifugal compressor.

Abstract: A method for controlling a pump for delivery of liquid to an organ over a series of fixed-length time intervals f, each interval f comprising a time t1 and a time t2 wherein t1+t2 equals the length of interval f. The method comprises allowing output pressure of the pump to decrease over time t1, increasing output pressure of the pump over time t2, comparing achieved pump output pressure to a predetermined pressure at about the end of interval f, and at least one of (i) adjusting t1 and t2 if necessary so the predetermined pressure is approximated by the output pressure at the end of the next interval f, and (ii) adjusting a rate of change of the output pressure during at least one of t1 and t2 if necessary so the predetermined pressure is approximated by the output pressure at the end of the next interval f.

Abstract: An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Abstract: Systems and processes are provided for gas separation using high-speed permanent magnet variable-speed motors to accelerate and decelerate centrifugal compressors suitable for use in pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA) processes.

Abstract: There is provided an electric compressor capable of being actuated rapidly. During the time when the operation of an automotive air conditioner is stopping, by heating a motor 12, a refrigerant on the outlet side 11b of a compressor body 11 is heated. Thereby, the temperature of refrigerant on the outlet side 11b is raised, and the refrigerant is prevented from being liquefied on the outlet side 11b of the compressor body 11, by which the automotive air conditioner can be actuated rapidly. Besides, by rotating the motor 12 at the number of revolutions lower than that at the time of normal operation, the refrigerant liquefied on the outlet side lib of the compressor body 11 may be pushed out.

Abstract: A technique for reducing the risk of free flow through a pump is disclosed. The technique includes sensing a pressure difference between the pump inlet and outlet. The pressure difference is mechanically communicated to a flow restricting element. The flow restricting element increases resistance to flow exiting the pump outlet in a relation to the pressure difference present between the pump inlet and pump outlet.

Abstract: The arrangement as overload protection for the mains voltage (U) comprises an electric motor (1), a compression unit having a compressor (2), a mains voltage-monitoring unit (3), a device for reducing the load on the motor (1) and a control arrangement (4). The control arrangement (4) is connected to the mains voltage-monitoring unit (3) and to the device for reducing the load on the motor (1) such that the motor (1) is disconnected from the load as soon as the mains voltage (U) falls below a predetermined, first threshold value. The load on the motor (1) comes from the pressure difference between the inlet (E) and the outlet (A) of the compressor (2), which is driven by the motor (1).

Abstract: A gas compression system is operable to deliver a flow of compressed gas to a point of use. The gas compression system includes a compressor that is operable to produce a flow of compressed gas at a first pressure, a motor operable to drive the compressor at a compressor speed, and a gas treatment member positioned to receive the flow of compressed gas from the compressor and deliver the flow of compressed gas to the point of use at a second pressure. A controller is operable to vary the compressor speed in response to a difference between the first pressure and the second pressure.

Abstract: Method for controlling an assist pump for fluid delivery systems with pulsatile pressure. If for example a heart assist pump is driven with a constant number of revolutions, it is achieved, that the blood is also delivered through the assist pump, even when the heart chamber is in the decontraction phase. With the present method it is achieved, that an assist pump only acts supportingly in the pressure phase of the main pump, in such a way, that the pressure difference between the input side and the output side of the assist pump is continuously determined and the number of revolutions of the assist pump is controlled in such a way, that the determined pressure difference does not fall below a predetermined value and the rate of flow does not sink below zero.

Abstract: A compressor diagnostic system incorporates a control which receives a plurality of data streams about various operational features of the compressor. As an example, both temperature and pressure of the suction and discharge refrigerant are taken and sent to the control. Moreover, information with regard to the power being supplied to the motor is taken and stored. All of this information is utilized at a control which compares the information to expected values and determines a fault based upon the evaluation. Moreover, in another feature of this invention, much of this data is stored, and maintained at the compressor. In the event of a compressor failure, this stored information will provide a maintenance worker with a good indication of why the compressor failed.

Abstract: In the process according to the invention for determining a nominal values curve of an installation (Hinstallation(Q), Pinstallation(Q)) for controlling the pump capacity of a pump (6) driven by an electric motor (10) with speed control in a closed system with variable capacity requirement, first all consumers in the installation are closed, one consumer operation parameter is determined at a consumer (4-n) arranged at a distance from the pump, the pump capacity is varied until the consumer operation parameter has reached a predetermined value, and, once this value has been reached, a pair of pump parameters representative for the instantaneous pump capacity is determined and stored in the controller. This measurement is repeated with different consumers being open, and from the stored values of the pairs of pump parameters the curve of nominal values (Hinstallation(Q), Pinstallation(Q)) of the installation is calculated by way of a mathematical process for establishing a curve.

Abstract: A method for determining the suction pressure of a centrifugal pump including the steps of determining pump torque and pump discharge pressure at at least two different speeds, forming a first order wave curve as a straight line using said pump torque and pump discharge and determining suction pressure from the y axis intercept of said line.