An electrical submersible pump (ESP) isolates its motor lubricant from pumped product without requiring a bellows, diaphragm, bladder, or external lubricant pressurizing system. A pair of nested isolation chambers below the motor housing are filled with a barrier fluid that is non-reactive, non-miscible, and higher in density than the pumped product and the motor lubricant. As the motor lubricant expands and contracts after pump start-up and shut-down, motor lubricant and barrier fluid are exchanged between the motor housing and the isolation chambers via three interconnections, while pumped product is exchanged with the inner barrier chamber, while being isolated from the motor housing. The interconnections extend between the bottom of the motor housing and the bottom of the outer barrier chamber, between the top of the outer barrier chamber and the bottom of the inner barrier chamber, and between the top of the inner barrier chamber and the pumped product.

The invention relates to a positive displacement pump 1 for conveying medical fluids, which pump has a pumping chamber 5 and a positive displacement element 15, and to a blood treatment apparatus comprising a positive displacement pump 1. In addition, the invention relates to a method for controlling a positive displacement pump 1 for conveying medical fluids. The positive displacement pump 1 according to the invention has an actuation member 20 in operative connection with the positive displacement element 20 for displacing or deforming the positive displacement element in order to convey the fluid into the pumping chamber or out of the pumping chamber, and a drive device 21 for displacing the actuation member 20. A control unit 14 is provided for to controlling the drive device 21 and an inlet valve 12 and outlet valve 13. The actuation member 20 is in operative connection with the positive displacement element 15 via a working chamber 19 that is filled with gas and has a sealed volume. In order to achieve a high conveying precision, the pressure in the working chamber 5 is kept constant when the positive displacement element 15 is moved.

A system and a method for cooling a prime mover and lube oil, comprising: a prime mover configured to drive a pump with a motor shaft; a prime mover cooling assembly that encases the prime mover, wherein the prime mover cooling assembly comprises: an air intake and an exhaust ventilator mounted above the prime mover; and a lube oil cooling assembly mounted above the prime mover, wherein the lube oil cooling assembly cools lube oil circulating within the pump and is mounted above the prime mover such that the lube oil cooling assembly does not hang off one or more sides of the prime mover and prime mover cooling assembly.

The invention concerns a method and an apparatus for operating a multi-phase pump which has a suction-side inlet (10) and a discharge-side outlet (20) and which pumps a multi-phase mixture charged with solids, comprising the following steps: a. pumping a multi-phase mixture into a discharge-side separation chamber (45), b. separating a gaseous phase from a liquid phase and a solid phase in the separation chamber (45), c. separating the liquid phase from the solid phase in the separation chamber (45), and d. supplying a portion of the liquid phase freed from the solid phase to the suction side.

The invention concerns a method and an apparatus for operating a multi-phase pump which has a suction-side inlet (10) and a discharge-side outlet (20) and which pumps a multi-phase mixture charged with solids, comprising the following steps: a. pumping a multi-phase mixture into a discharge-side separation chamber (45), b. separating a gaseous phase from a liquid phase and a solid phase in the separation chamber (45), c. separating the liquid phase from the solid phase in the separation chamber (45), and d. supplying a portion of the liquid phase freed from the solid phase to the suction side.

A system of pumps wherein a first hydraulic motor operatively connected to a first master pump can hydraulically drive a second hydraulic motor operatively connected to a second slave pump. A hydraulic fluid outlet of the first hydraulic motor is fluidically connected to a hydraulic fluid inlet of the second hydraulic motor whereby the first hydraulic motor, operatively connected to the first pump, drives the second hydraulic motor, operatively connected to the second pump, in a hydraulically synchronized manner.

A monitoring system may include strain gauges and position sensors corresponding to multiple pressure pumps. The strain gauge for each pressure pump may measure the strain in a respective chamber of each pump. The position sensor for each pump may measure the position of a rotating member of each pump. The monitoring system may also include one or more computing devices for determining actuation delays associated with valves corresponding to the respective chamber of each pump using expected actuation points and actual actuation points of the valves. The computing devices may compare the actuation points for the valves of all of the pressure pumps to determine a condition of a valve in one of the pressure pumps.

A monitoring system may include strain gauges and position sensors corresponding to multiple pressure pumps. The strain gauge for each pressure pump may measure the strain in a respective chamber of each pump. The position sensor for each pump may measure the position of a rotating member of each pump. The monitoring system may also include one or more computing devices for determining actuation delays associated with valves corresponding to the respective chamber of each pump using expected actuation points and actual actuation points of the valves. The computing devices may compare the actuation points for the valves of all of the pressure pumps to determine a condition of a valve in one of the pressure pumps.

A piston pump, in particular a high-pressure fuel pump for an injection system of an internal combustion engine, has a piston and a working chamber which is delimited by the piston. The piston has a running surface section, via which the piston is guided with a guide element, and is configured and developed in such a way that the running surface section of the piston tapers in cross section towards its end which faces the working chamber.

A piston pump, in particular a high-pressure fuel pump for an injection system of an internal combustion engine, has a piston and a working chamber which is delimited by the piston. The piston has a running surface section, via which the piston is guided with a guide element, and is configured and developed in such a way that the running surface section of the piston tapers in cross section towards its end which faces the working chamber.