A fluid control device includes a piezoelectric pump, a piezoelectric pump, a container, and a control unit. The piezoelectric pumps and are connected in series. The piezoelectric pump is an upstream-side pump, and the piezoelectric pump is a downstream-side pump. The control unit controls driving of the piezoelectric pumps. The control unit makes the driving start timing of the piezoelectric pump on an upstream side earlier than the driving start timing of the piezoelectric pump on a downstream side.

Included are: a compressor including a compression mechanism that compresses refrigerant, and a motor that drives the compression mechanism; an inverter that applies desired voltage to the motor; an inverter controller that controls the inverter; a high-pressure switch that operates when a discharge pressure of the compressor becomes a preset pressure or higher; and a thermal protector that operates when the temperature of the compressor becomes a preset temperature or higher, wherein the high-pressure switch and the thermal protector are installed on a power supply line for supplying power to the inverter, and the high-pressure switch is opened when the discharge pressure of the compressor becomes the preset pressure or higher, or the thermal protector is opened when the temperature of the compressor becomes the preset temperature or higher, to interrupt power supply to the inverter.

Included are: a compressor including a compression mechanism that compresses refrigerant, and a motor that drives the compression mechanism; an inverter that applies desired voltage to the motor; an inverter controller that controls the inverter; a high-pressure switch that operates when a discharge pressure of the compressor becomes a preset pressure or higher; and a thermal protector that operates when the temperature of the compressor becomes a preset temperature or higher, wherein the high-pressure switch and the thermal protector are installed on a power supply line for supplying power to the inverter, and the high-pressure switch is opened when the discharge pressure of the compressor becomes the preset pressure or higher, or the thermal protector is opened when the temperature of the compressor becomes the preset temperature or higher, to interrupt power supply to the inverter.

Automatic electric actuation of the pumping mechanism of a liquid dispenser apparatus is provided by configuring a hollow tube to cooperate with an electromagnetically driven actuator and further configuring the hollow tube to inter-fit with a stem of a liquid dispensing pump. Actuation of the actuator may, for example, drive the pump stem downwardly to cause a pumping action. Suitable actuators include, for example, solenoids, voice coil actuators and stepping motors.

Automatic electric actuation of the pumping mechanism of a liquid dispenser apparatus is provided by configuring a hollow tube to cooperate with an electromagnetically driven actuator and further configuring the hollow tube to inter-fit with a stem of a liquid dispensing pump. Actuation of the actuator may, for example, drive the pump stem downwardly to cause a pumping action. Suitable actuators include, for example, solenoids, voice coil actuators and stepping motors.

Aspects are provided for positive displacement pumps and methods and systems for controlling such pumps to provide alerts based on user configurable tubing usage limits. A pump may include a user interface, a memory storing processor executable instructions, and a processor coupled with the user interface and the memory and configured to execute the instructions to receive a configuration of a tubing usage limit via the user interface. The processor may be configured to operate the pump according to a program. The processor may be configured to measure a tubing usage during pump operation. The processor may be configured to generate an alert when the tubing usage reaches the tubing usage limit.

A fracturing apparatus may include a power supply platform; a gas turbine engine; a generator; and one or more rectifiers. At least two of the gas turbine engine, the generator, and the one or more rectifiers are arranged on the power supply platform. A first end of the generator is connected to the gas turbine engine. A second end of the generator is connected to the one or more rectifiers. The generator is configured to output a voltage to the one or more rectifiers.

Methods and apparatus for operating a rod pumping unit for a wellbore are provided. One example method includes measuring vibration data in the time domain using at least one sensor coupled to a housing for a moving component of the rod pumping unit; converting the vibration data in the time domain to vibration data in the frequency domain; determining that: (1) at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or (2) a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold; and outputting an indication based on the determination.

Methods and apparatus for operating a rod pumping unit for a wellbore are provided. One example method includes measuring vibration data in the time domain using at least one sensor coupled to a housing for a moving component of the rod pumping unit; converting the vibration data in the time domain to vibration data in the frequency domain; determining that: (1) at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or (2) a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold; and outputting an indication based on the determination.

A method of controlling a gas compression system includes comparing an engine load of an engine of the gas compression system during operation to a load threshold and controlling a suction valve coupled to an intake of a reciprocating compressor. The suction valve is controlled based at least in part on the comparison of the engine load to the load threshold. Controlling the suction valve includes incrementing the suction valve toward a closed position to reduce flow of a gas into the intake when the engine load is greater than or equal to the load threshold.