Types Pumps can be broadly categorized according to three techniques: positive displacement, momentum transfer, and entrapment. Positive displacement pumps use a mechanism to repeatedly expand a cavity, allow gases to flow in from the chamber, seal off the cavity, and exhaust it to the atmosphere. Momentum transfer pumps, also called molecular pumps, use high-speed jets of dense fluid or high-speed rotating blades to knock gas molecules out of the chamber. Entrapment pumps capture gases in a solid or adsorbed state; this includes cryopumps, getters, and ion pumps.
types pUmPS caN Be brOadlY cateGoRiZED aCcORdiNg tO threE teChniqUEs: PositivE displacement, moMEntuM TRansFER, aND enTrAPment. POSitiVE disPlaCemenT pUmpS use a mecHanISM to rEpeaTEDly eXpand a cAvitY, allow GaseS to Flow In frOm the cHamBeR, Seal Off THE CavIty, and ExhauSt it to THe aTMospheRe. MOmenTum traNsfEr pUmps, also CAllED mOlEcULaR PumPs, use high-speEd jets Of dense fluID or HiGh-speed rotaTInG BlAdes to knoCk GAs MolecULes out of THe cHaMbER. ENtraPment pumPS capture gases in a sOliD Or adSORbEd sTaTE; this inclUdeS CrYOpuMpS, GEtTERS, ANd ioN pumPs.