Gas trap vacuum pump is a gas molecules are adsorbed or condensed in the pump on the surface of the vacuum pump can be divided into the following types. 1. Adsorption pump, which is a trapped vacuum pump that relies on the physical adsorption of adsorbents with large surface area, such as porous material. For example molecular sieve adsorption pumps. 2. A getter pump, a vacuum pump that uses a getter to chemically trap gas. Getters are usually metals or alloys that exist in the form of lumps or deposited fresh films. For example, titanium sublimation pump and aluminum-zirconium-aluminum suction pump of this type.