A vacuum pump is a special device that extracts any liquid or airborne substance from a determined enclosed area. Vacuum pumps differ in construction from pressure pumps, which are also used in HVAC/R. There are three main designs of these devices. The first one is called a positive displacement pump, and it creates an empty space for the substance to fill in, then closes it off and extracts the substance through a special exhaust pipe. The second type is a molecular pump. It works by accelerating particles of a substance and taking them out of the system via a special outlet. Finally, an entrapment pump uses low temperatures to turn substances into liquid or solid state, and then take the substance out through the exhaust port. Pumps are widely utilized in HVAC/R systems as well as servicing equipment. Such devices may be used as a part of an RRM or as a stand-alone device. On Mega Depot, you can buy various pumps as well as any additional equipment at the best prices.