A gas booster for increasing a pressure of a gas includes a gas cylinder and a drive. The gas cylinder defines a chamber having an inlet and an outlet. A piston is actuatable within the gas cylinder to draw gas into the chamber through the inlet at a first pressure and to push the gas out of the chamber through the outlet at a second pressure that is higher than the first pressure. The drive includes an electric motor coupled to the piston of the gas cylinder by a mechanical connection to actuate the piston.

Disclosed is a portable pump including a reciprocating air compressor arrangement with a crank driving a connecting rod and a piston within a cylinder, the connecting rod being connected to the crank and piston, the crank actuating the piston in a reciprocating motion within and relative to the cylinder, an electric motor having a drive shaft mounted to the crank and rotatable about a drive shaft axis, the drive shaft axis being at least substantially coaxially aligned with an axis of rotation of the crank, a control unit communicating with the electric motor to control the pump, a power supply communicating with the control unit to power the control unit and electric motor, a common housing containing the electric motor, reciprocating air compressor arrangement, control unit, and power supply, and an outlet fluidly connected to the reciprocating air compressor arrangement for fluidly engaging with an pumpable object.

Provided is a tube pump including: a housing unit that has an inner peripheral surface, which is formed in an arc shape around an axis, along which a tube with flexibility is disposed, and that is opened toward one end side along the axis; a pair of roller units that are accommodated in the housing unit and rotate about the axis in a state in which the tube is blocked; a pair of drive units that cause each of the pair of roller units to rotate about the axis in the same direction; and a cover member that is disposed in the housing unit such that the cover member covers the pair of roller units and provides an annular opening region into which the tube is able to be inserted toward the inner peripheral surface.

A reciprocating compressor including a cylinder; a piston disposed to reciprocate a certain distance inside the cylinder; a connecting rod connected to the piston; a rotation shaft configured to operate the connecting rod; a rotor configured to rotate integrally with the rotation shaft; and a stator disposed inside of the rotor along a direction toward the rotation shaft or outside the rotor along the direction toward the rotation shaft. A speed fluctuation rate of the rotor is 20% or less is achieved based on consideration of a relationship between a moment of inertia of the rotor, an internal pressure of the cylinder, a cross-sectional area and a stroke length of the piston, and a minimum speed of the rotor.