A pressure-controlling device (10) includes a pump (21), a connection pipe (30), a first valve (41), and a second valve (42). The pump (21) has an inlet port (211) and an outlet port (212). The connection pipe (30) has a first end in communication with the outlet port (212), and a second end in communication with the inlet port (211) and that has a first space (31) that contains the first end, a second space (32) that contains the second end, and a third space (33) that is located between the first space (31) and the second space (32).

A gas compressor includes inverters, a plurality of compressor units and a control device for controlling each of the inverters. The control device increases the number of compressor bodies to be operated after confirming that the rotational speed of the operational motors will reach a steady value immediately after causing the number of the compressor bodies to be operated to increase.

Pumps for noncontact tonometry are provided. In one embodiment, a pump for noncontact tonometry includes a compression pump, a compression chamber, a first pressure sensor in communication with the compression chamber, a surge chamber, and a valve separating the compression chamber and surge chamber. The compression pump compresses a first volume of gas into the compression chamber. When the first pressure sensor detects a threshold pressure in the compression chamber, the valve opens and releases the gas into a surge chamber, where it combines with a gas residing in the surge chamber to form a puff of gas that escapes from the surge chamber through a flow-limiting nozzle. The components of the pump, which relies on passive rather than active components to create the controlled puff, can be assembled to have a profile that is portable and fit for home use.

A cordless compressor has an air storage tank, a pump, a motor for driving the pump, and a controller circuit electrically connected to the motor. A pressure switch assembly is connected to the controller circuit. The pressure switch assembly has first and second pressure switches for sensing pressure within the air storage tank. The controller circuit controls de-activation of the motor depending upon status of the first and second pressure switches.

There are provided an operation number control device and a method for controlling the same that can level the operation times of the fluid machines, which are connected to the operation number control device. A fluid machine system comprises a plurality of fluid machines, and an operation number control device capable of individually controlling start and stop of the fluid machines. The operation number control device sets a continuous operation time for each of the fluid machines based on total operation times of the fluid machine and other fluid machines. When among fluid machines in operation, there is a fluid machine for which the continuous operation time set for the fluid machine has elapsed and there is a fluid machine at stop, the operation number control device causes the fluid machine at stop to start and causes the fluid machine to stop.

A pumping system includes a primary suction tank including a first pressure sensor operatively connected to a first portable suction control for measuring a first pressure of a fluid coming from the primary suction tank, and a first flow meter operatively connected to the first portable suction control for measuring a first flow rate of the fluid coming from the primary suction tank, wherein an output of the primary suction tank is controlled by a first valve, a secondary suction tank, a rig pump operatively connected to the primary suction tank, and the secondary suction tank, and a rig stand pipe connected to a drilling well, and a controller operatively connected to the first portable suction control, the first valve, and a second flow meter configured to measure a second flow rate of the fluid coming out of the rig pump.

The purpose of the present invention is to provide an air compressing apparatus capable of establishing a sufficient air-filling rate while reducing noise at the initiation of operations. To solve this problem, in the present invention, the air compressing apparatus comprises a compressor body that compresses air, a motor that drives the compressor body, an inverter that controls the rotation speed of the motor, a control circuit connected to the inverter, and a pressure sensor that detects the pressure of air compressed in the compressor body, wherein the control circuit controls operation of the compressor body by operating at a low speed activation mode that operates the compressor body at a low speed rotational frequency lower than a maximum rotational speed when the air compressing apparatus is activated, and on the basis of a pressure value detected by the pressure sensor and elapsed time from activation, switching from the low speed activation mode to a normal operating mode that operates at variable frequencies including a maximum rotational frequency.

An air compressor includes: a motor actuating a mechanism to generate compressed air; a tank part in which the compressed air is stored; a pressure detector detecting a pressure value in the tank part; and a controller driving the motor when the pressure value is equal to or smaller than an ON pressure value and to stop drive of the motor when the pressure value is equal to or greater than an OFF pressure value. The controller executes processing for detecting a continuous drive time or a continuous stop time of the motor and changing at least one of the ON pressure value, the OFF pressure value and an output of the motor, and the controller detects a change amount of the pressure value, and to determine an execution cycle of the processing or a change amount of a value in the processing, based on the detected change amount.

An air compressor includes a compressor main body that compresses air; a storage tank that stores the gas compressed by the compressor main body; a motor that rotates a rotary shaft to drive the compressor main body; and a control unit that controls a drive of the motor. In a case where a value of a voltage to be supplied to the motor is lower than a first voltage value, the control unit detects a stop time of the compressor and changes an operation stop pressure which is a pressure to stop the drive of the motor, based on the stop time.

A cordless compressor has an air storage tank, a pump, a motor for driving the pump, and a controller circuit electrically connected to the motor. A pressure switch assembly is connected to the controller circuit. The pressure switch assembly has first and second pressure switches for sensing pressure within the air storage tank. The controller circuit controls de-activation of the motor depending upon status of the first and second pressure switches.