A liquid feeding device includes a discharge channel, a pump part, a feeding pressure sensor, a non-discharge pressure sensor, a pre-compression part, and a pre-compression speed determination part. The pump part has plunger pumps connected in series or parallel. At least one of the plunger pumps is a closed pump in which communication with the discharge channel is disconnected during a non-discharge time. The pre-compression part causes the closed pump that is after the suction process for sucking the liquid into a pump chamber is completed and during the non-discharge time to execute a pre-compression process to perform a discharge operation until a non-discharge pressure is substantially the same as a feeding pressure based on output of the feeding pressure sensor and output of the non-discharge pressure sensor. The pre-compression speed determination part determines a pre-compression speed of the closed pump in the pre-compression process.

A pump monitoring system for use in wellbore operations includes a strain gauge that can be positioned on a fluid end of a pump and at least one pressure transducer to measure relative pressure. A computing device can be connected to the strain gauge and the pressure transducers. The computing device executes programming instructions to identify failures of specific valves by correlating the strain signal to an actual pressure associated with the specific valve in the pump section. The processor then determines whether a pump pressure corresponds to the actual pressure associated with the specific valve, and if so, displays an indication that the specific valve in the pump section has failed.

A binary pump in which an operation controller causes each of two liquid delivery pumps to execute, while a secondary discharge process is executed, a suction process, a first pre-pressurizing process, and a standby process. The operation controller causes each of the two liquid delivery pumps to execute a second pre-pressurizing process before proceeding from the secondary discharge process to the primary discharge process. Furthermore, the operation controller causes, as long as continuous liquid delivery by each of the two liquid delivery pumps is not interrupted, at least one of the two liquid delivery pumps to execute avoidance operation of interrupting the standby process and proceeding to the second pre-pressurizing process by using the operation state of each of the two liquid delivery pumps, so as to avoid overlap of execution time zones of the primary discharge processes of the two liquid delivery pumps.

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 drive device is provided comprising a working pump, the working pump connected to a membrane fluid pump, and the working pump having a working piston able to oscillate axially between two reversal points for contracting and expanding a working chamber, and a control unit for controlling a movement of the working piston between the two reversal points. The controlled movement of the working piston comprises three temporally successive phases, in a first phase the working piston is accelerated to a speed that is greater than a speed at the end of the first phase, in a second phase the working piston is moved such that a specified speed of the working piston, a specified relative pressure in the working chamber, or a specified force of the working piston is substantially kept constant, and in a third phase the working piston is moved at a negative acceleration.

A surge suppressor includes a boost mechanism configured to balance pressures between a working fluid and a process fluid. The boost mechanism includes a boost member that is acted on by a charge pressure of the working fluid. A shaft extends from the boost member to a pressure control member bounding the process fluid and acting on the process fluid. The boost member can have a larger effective area than the pressure control member to provide a pressure multiplication between the charge pressure and the process fluid pressure. In addition, pressure control valves are mounted to an air housing and actuated open by the boost mechanism. Actuating one of the pressure control valves open increases the charge pressure. Actuating the other pressure control valve open decreases the charge pressure.

A monitoring system may include at least a strain gauge and a computing device for determining a bulk modulus of a fluid system of a pressure pump using strain measurements. The strain gauge may determine strain in a chamber of the pressure pump. The computing device may receive a strain signal generated by the strain gauge and may correlate the strain signal to pressure to determine a change in pressure during a period in which fluid is isolated in the chamber. The computing device may use the change in pressure during this period to determine a bulk modulus of the fluid system.

Disclosed are embodiments of a pumping system with connectable and disconnectable pumping assemblies coupled to suction and discharge manifolds. In an embodiment, the pumping system includes a pulsation dampening assembly including a variable volume chamber fluidly coupled to the discharge manifold. In addition, the pumping system includes a controller coupled to the pumping assemblies. The controller is configured to detect a pressure pulsation based on a measurement from at least one of the pressure sensors, and is configured to adjust the rotational speed of the driver of at least one of the pump assemblies. In addition, the controller is configured to adjust a volume of the variable volume chamber of the pulsation dampening assembly based at least in part on the measurement from the at least one of the pressure sensors.

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 Metering pump includes a displacement element (4), a drive system with an electric drive motor (12) driving the displacement element (4) and a control device (22) controlling the electric drive motor (12). The control device (22) is configured in such a manner that it detects the current position of the displacement element (4), detects the torque (M) of the electric drive motor (12) at several positions of the displacement element (4) and monitors the torque (M) in relation to the position of the displacement element (4), and a method for controlling such metering pump.