There are two standard CO2 pumps. These are air-driven, liquid pumps capable of delivering CO2 from a cylinder (nominally 60 BAR at room temperature) to a pressure of 680 BAR.
Because they are pneumatic, they are inherently more compact, safer, cleaner, quieter and requiring less maintenance than either electric or hydraulic pumps.
In both pumps, the pressure is set and shown by a digital readout. There is another gauge to show the air pressure.
Pump (product #7321) delivers a flow rate of 400ml/min and pump (product # 7316) delivers 800ml/min. (Flow rates are calculated by the stroke volume of an incompressible liquid.)