A method of controlling the injection of hydraulic fluid into a high pressure diaphragm compressor having a hydraulic system, the method including: measuring a representation of pressure in a high-pressure part of the hydraulic system of the diaphragm compressor, and maintaining a desired pressure in the high-pressure part of the hydraulic system by adding hydraulic fluid to the high-pressure part of the hydraulic system under the control of a controller on the basis of the measuring of pressure.

A pressure sensor having a housing connected to a compressor head, the housing including a piston movably mounted in a cylinder, the cylinder is fluidly connected to a high-pressure part of a hydraulic system of the compressor, where the piston is adapted to be moved in a first direction away from the compressor head by the pressure of the hydraulic fluid in the high-pressure part, thereby moving a displacement member which is movably attached to the housing by one or more flexible suspensions, and the piston is adapted to be moved in a second direction towards the compressor head by the flexible suspension via the displacement member.

A high-pressure compressor having a hydraulic system and a gas chamber, where the hydraulic system includes a reservoir, connected to a hydraulic fluid chamber by a hydraulic flow path and a pump assembly positioned in the hydraulic flow path, and the compressor furthermore includes a control element controlling the flow of hydraulic fluid in the hydraulic flow path and thereby the pressure in the hydraulic fluid chamber, where the control element and the pump assembly is configured for controlling the pressure of hydraulic fluid in the hydraulic fluid chamber when the compressor is not in operation.

An apparatus includes a bootstrap accumulator having multiple fluid expansion volumes each configured to receive fluid. The bootstrap accumulator also includes a piston assembly configured to move within the fluid expansion volumes based on pressures within the fluid expansion volumes. The piston assembly includes (i) a fluid pathway that couples the fluid expansion volumes and (ii) a bypass valve configured to selectively open or block the fluid pathway. The piston assembly could also include multiple pistons and a connecting rod coupling the pistons. The fluid pathway could include a narrower path through a first portion of the connecting rod and a wider path through a second portion of the connecting rod. The bypass valve could include a ball and a spring configured to push the ball to block the narrower path through the first portion of the connecting rod.

A fracturing pump system includes a fluid end having a cylinder and a piston movable to pressurize fluid in the cylinder. The cylinder has at least one cylinder sidewall, packing located to prevent fluid from leaking between the piston and the cylinder sidewall, and a hydraulically-driven assembly configured to apply variable amounts of pressure on the packing.

A method for operating a construction-material and/or viscous-material pump for conveying construction material and/or viscous material has the steps of: a) determining a required value of a power or of a size of the motor system, corresponding to the power, for moving the conveying piston, b) setting, on the basis of the required value, a speed value of the motor system in such a manner that a power and/or speed reserve value between an operating point, wherein the operating point is defined by the required value of the power or of the size and the speed value, and a characteristic curve of the motor system, wherein the characteristic curve is defined by maximum values of the power or of the size and speed values, wherein maximum values are different for different speed values at least in sections, is greater than or equal to a reserve limit value.

A gas booster for increasing a pressure of a gas includes a gas cylinder and a drive. The gas cylinder defines a chamber having an inlet and an outlet. A piston is actuatable within the gas cylinder to draw gas into the chamber through the inlet at a first pressure and to push the gas out of the chamber through the outlet at a second pressure that is higher than the first pressure. The drive includes an electric motor coupled to the piston of the gas cylinder by a mechanical connection to actuate the piston.

A conveying device for conveying a viscous material from a container includes a follower plate that can be inserted into the container, and a pump by means of which the viscous material can be conveyed through the follower plate. Moreover, a measuring chamber for accommodation of a measuring sample of the viscous material is provided. The measuring chamber includes a closable material inlet opening for this purpose. A closable disposal line leads away from the measuring chamber. Moreover, a closable material return line extends from the measuring chamber via the follower plate into the container. The conveying device also includes a controller that is designed and can be operated appropriately such that it determines the compressibility of each of multiple measuring samples. The controller opens the disposal line or the material return line to the measuring sample present in the measuring chamber as a function of the compressibility thus determined.

An apparatus includes a bootstrap accumulator having multiple fluid expansion volumes each configured to receive fluid. The bootstrap accumulator also includes a piston assembly configured to move within the fluid expansion volumes based on pressures within the fluid expansion volumes. The piston assembly includes (i) a fluid pathway that couples the fluid expansion volumes and (ii) a bypass valve configured to selectively open or block the fluid pathway. The piston assembly could also include multiple pistons and a connecting rod coupling the pistons. The fluid pathway could include a narrower path through a first portion of the connecting rod and a wider path through a second portion of the connecting rod. The bypass valve could include a ball and a spring configured to push the ball to block the narrower path through the first portion of the connecting rod.

The invention relates to a blood treatment device having at least one metering line which opens into a fluid circuit, wherein a conveyor module is arranged in the metering line and comprises a membrane pump and a valve which is arranged at the pressure side thereof and which can act both as a blocking valve and as a restricting valve.