A compressor control apparatus and method differently compensate for a duty ratio of a control signal during a period in which the compressor performs a compression stroke and a period in which the compressor performs a suction stroke, respectively, to generate the control signal for controlling a compressor.

A pumping system includes a head having an opening and an injection port. The head is for holding content to be forced through the injection port. A bladder is within the head. The bladder is between the content and the opening. A plunger is configured to move through the opening of the head and to apply force within the bladder. The plunger may be movable in a discharge stroke to force the bladder against the content and thereby force the content through the injection port.

The present disclosure relates generally to alternating tangential flow (ATF) perfusion pumping methods, including novel methods for generating positive and negative pressure at the point of use, and more particularly, to apparatuses, systems and methods for use of the same.

A method operates a construction material and/or viscous-material pump having: at least one conveying cylinder, the conveying cylinder being designed to receive and discharge construction material and/or viscous material; and at least one conveying piston, the conveying piston being disposed in the conveying cylinder for movement in order to draw construction material and/or viscous material into the conveying cylinder and to displace drawn-in construction material and/or viscous material out of the conveying cylinder. The method includes: conveying construction material and/or viscous material, by movement of the conveying piston in order to draw in and displace construction material and/or viscous material; sensing a position variable during the movement, the position variable characterizing a position of the conveying piston along its stroke in the conveying cylinder; sensing a conveying variable during the movement, the conveying variable being of a different type than the position variable and characterizing the conveying of construction material and/or viscous material by the pump; and determining a profile of a subsequent movement of the conveying piston by linking the sensed position variable and the sensed conveying variable to each other; and controlling the subsequent movement in accordance with the determined profile.

The exemplary embodiments control solvent pumps so that system flow is constant. One or more controllers may control the flow rate produced by the pumps over time. The one or more controllers control a first pump so that, as the first pump is refilling, a second pump maintains a sufficient flow rate to compensate for the lost flow due to the refilling event. In some exemplary embodiments, the one or more controllers control the timing of the refilling event for the first event such that the refilling event overlaps with the equilibrating of the chromatography column with solvent(s) from the second pump. Similarly, the one or more controllers control the timing of the refilling event for the second pump such that the refilling event overlaps with the equilibrating of the chromatography column.

A variable displacement reciprocating piston unit includes a sensor probe, a target, a piston having a top dead center position and a bottom dead center position, and a signal processing unit. The sensor probe, the target, and the piston are located in relation to each other so that the target is moved from being absent from the sensor probe to being present at the sensor probe when the piston travels towards the top dead center position, and the target is moved from being present at the sensor probe to being absent from the sensor probe when the piston travels towards the bottom dead center position. The signal processing unit generates a signal indicating a stroke speed and a stroke length of the piston from a signal from the sensor probe indicating a presence and/or an absence of the target as the target moves relative to the sensor probe.

The lubricant level within a reservoir is difficult to monitor, leading to the reservoir being refilled more often than necessary to ensure that the reservoir always contains lubricant. A lubricant level sensing system is connected to and monitors various aspects of the pump assembly that draws lubricant from the reservoir. The pump assembly displaces a known volume of lubricant with each pump stroke. A lubricant-level estimator calculates an estimated lubricant level remaining in the reservoir based on a stroke-count value as sensed from the pump assembly and on a reference value stored in a memory. The estimated lubricant level provides the lubricant remaining and the rate of usage such that maintenance can be scheduled ahead of time to prevent the reservoir running dry.

A diaphragm pump includes a reciprocable diaphragm, an actuator including a motor, and a control device. The control device resets an origin of the diaphragm in a reciprocating direction, when detecting a step-out of the motor. After resetting the origin, the control device activates the actuator to move the diaphragm to the origin.

A diaphragm pump includes a reciprocable diaphragm, an actuator including a motor, and a control device. The control device resets an origin of the diaphragm in a reciprocating direction, when detecting a step-out of the motor. After resetting the origin, the control device activates the actuator to move the diaphragm to the origin.

An example system for detecting mud pump stroke information comprises a distributed acoustic sensing (DAS) data collection system coupled to a downhole drilling system, a stroke detector coupled to a mud pump of the downhole drilling system configured to detect strokes in the mud pump and to generate mud pump stroke information based on the detected strokes, and a fiber disturber coupled to the stroke detector and to optical fiber of the DAS data collection system configured to disturb the optical fiber based on mud pump stroke information generated by the stroke detector. The system further comprises a computing system comprising a processor, memory, and a pulse detection module operable to transmit optical signals into the optical fiber of the DAS data collection system, receive DAS data signals in response to the transmitted optical signals, and detect mud pump stroke information in the received DAS data signals.