The present disclosure provides an air pump device, including a housing; a high-pressure air pump, a low-pressure air pump and a public pipeline are arranged in the shell; the high-pressure air pump is a reciprocating air pump, and includes a motor, a piston tube and a piston; the piston is arranged in the piston tube; the motor is used for driving the piston to move in the piston tube; an output shaft of the motor is perpendicular to an axial direction of the piston tube; an air outlet end of the piston tube is connected with the public pipeline, and the piston tube and the public pipeline are parallel or located on the same straight line; the low-pressure air pump is a blowing-type air pump, and includes a shell and a fan assembly.

A hydraulic system includes: a cylinder in which an interior of a tube is divided by a piston into a first pressure chamber and a second pressure chamber; a first bidirectional pump connected to the first pressure chamber by a first supply/discharge line; a second bidirectional pump connected to the second pressure chamber by a second supply/discharge line and coupled to the first bidirectional pump in a manner enabling torque to be transmitted between the first and second bidirectional pumps; a relay line connecting the first and second bidirectional pumps such that a hydraulic liquid discharged from one of the first and second bidirectional pumps is introduced into the other of the first and second bidirectional pumps; and an electric motor that drives the first or second bidirectional pump. At least one of the first and second bidirectional pumps is a variable displacement pump whose delivery capacity per rotation is freely variable.

A hydraulic pump (6) comprising: a housing (20) having first and second inlets (100a, 100b) and first and second outlets (102a, 102b); a crankshaft (4) extending within the housing (20) and having axially offset first and second cams (62, 64); first and second groups (30, 32) of piston cylinder assemblies provided in the housing (20), each of the said groups (30, 32) having a plurality of piston cylinder assemblies having a working chamber of cyclically varying volume and being in driving relationship with the crankshaft (4); one or more electronically controllable valves (40) associated with the first and second groups (30, 32); and a controller (70) configured to actively control the opening and/or closing of the said electronically controllable valves (40) on each cycle of working chamber volume to thereby control the net displacement of fluid by the first and second groups (30, 32), wherein at least the first group (30) comprises a first piston cylinder assembly in driving relationship with the first cam (62) and a second piston cylinder assembly in driving relationship with the second cam (64), and wherein the first group is configured to receive working fluid from the first inlet (100a) and to output working fluid to the first outlet (102a) and the second group is configured to receive working fluid from the second inlet (100b) and to output working fluid to the second outlet (102b).

A closing unit system for a blowout preventer (BOP) stack includes a first fluid reservoir, a first power source, a first pump system fluidly coupled to the first fluid reservoir and electrically coupled to the first power source, and a valve manifold fluidly coupled to the first pump system via a closing unit hose assembly and configured to couple to the BOP stack. The closing unit system also includes one or more processors that are configured to receive an input indicative of an instruction to adjust an actuator associated with the BOP stack, and instruct the first power source to provide power to the first pump system to cause the first pump system to pump a fluid from the first fluid reservoir to the valve manifold in response to the input.

A method for controlling a compressor system comprising a plurality of compressors, wherein the compressor system is intended to maintain a predefined excess pressure in a pressurized fluid system, wherein decisions are met at fixed or variable intervals as to switching operations for adapting the system to current conditions, wherein —in a pre-selecting step, switching alternatives are excluded from the plurality of combinatorially available switching alternatives, —in a main selecting step, remaining switching alternatives are weighed against one another while referring to one or more optimization criterion (criteria) and optimum switching alternatives are selected from among the given criteria, and —in a control step, the selected switching alternative is output for implementation in the compressor system.

A multistage compressor including: at least a first compressor main body and a second compressor main body configured to suck compressed gas discharged from the first compressor main body to discharge the compressed gas with higher pressure; a first driving source configured to drive the first compressor main body; a second driving source configured to drive the second compressor main body; an intermediate pipe configured to connect a discharge side of the first compressor main body and a suction side of the second compressor main body; a low-pressure side discharge piping system branched from the intermediate pipe; an on-off valve disposed in the low-pressure side discharge piping system and configured to switch permission and prohibition of a flow of compressed gas discharged from the first compressor main body; and a control unit configured to control driving of the first driving source and the second driving source.

A method of operating a vacuum pump system, the method including the steps of: operating a primary vacuum pump having a variable speed motor; connecting at least two secondary vacuum pumps in parallel with said primary vacuum pump; dividing the secondary vacuum pumps in groups, each group including at least one secondary vacuum pump; and assigning a priority for each of said groups. The method further includes the steps of measuring the inlet pressure p1, comparing the measured inlet pressure p1 with a predetermined pressure value p0, and if p1 is higher than p0, starting the secondary vacuum pump at a first predetermined startup load S.sub.startup,1 if it includes a fixed speed motor, and/or starting the secondary vacuum pump at a second predetermined startup load S.sub.startup,2, if it includes a variable speed motor.

Systems and methods for operating hydraulic fracturing units to pump fracturing fluid into a wellhead may include receiving a target flow rate and/or a target pressure for fracturing fluid supplied to the wellhead. The systems and methods may increase a flow rate from the hydraulic fracturing units according to a controlled increasing flow rate schedule toward the target flow rate and/or target pressure. When it has been determined the target flow rate and/or target pressure has been achieved, the systems and methods also may include operating the hydraulic fracturing units to maintain the target flow rate and/or target pressure. When the target flow rate has not been achieved, the systems and methods also may include generating notification signals, and/or when the target pressure has not been achieved, the systems and methods further may include operating the hydraulic fracturing units to maintain a maximum flow rate.

A multi-stage compressor includes a compression module configured to compress a refrigerant therein through reciprocation of a plurality of pistons provided in a front housing, a rear housing coupled to the front housing to define an internal space between the front housing and the rear housing; a separation plate located between the front housing and the rear housing to separate the internal space between the front housing and the rear housing into a front space and a rear space; and a partition wall coupled to the rear housing to partition the rear space into an injection space before a refrigerant injected thereinto is primarily compressed, a primary discharge space from which the refrigerant is discharged in a primary compressed state by some of the pistons, and a secondary discharge space from which the primary compressed refrigerant is discharged.

Most multistage compressors specify a maximum inlet pressure that may be supplied to the compressor to stay within designed limits. If the supply gas to be compressed is at a higher pressure than the specified maximum inlet pressure, then its pressure must be reduced before connecting it to the compressor. This pressure reduction is inefficient. The present invention avoids reducing the inlet pressure by routing the supply gas directly to the appropriate compression stage depending on its inlet pressure such that the compressor loads are still within the specified limits of the equipment.