Miniature vacuum pumps, often called small vacuum pumps due to their small size, are defined as follows: a miniature vacuum pump has one inlet and one outlet, capable of continuously creating a vacuum or negative pressure at the inlet and a slight positive pressure at the outlet; the working medium is primarily gas, and it is a compact instrument.
By connecting a sealed container (initially at atmospheric pressure of 100 kPa) to a miniature vacuum pump and continuously evacuating it, the gas pressure inside the sealed container will eventually drop below atmospheric pressure, reaching an absolute pressure of 60 kPa. Furthermore, through special technological improvements, in addition to single-function pumping miniature vacuum pumps, dual-purpose pumping and evacuation pumps can be developed (i.e., the exhaust end can generate relatively large positive pressure), used for pressurization, filling, overcoming system resistance, etc. There are also unique water-gas dual-purpose miniature vacuum pumps, which can be used in situations requiring long-term idling or dry running, unlike ordinary water pumps which are damaged by idling or dry running.