A vacuum pump is a type of pump, which is used to remove gas molecules from a sealed volume in order to leave behind a partial vacuum. Vacuum pumps are used in many industrial and scientific processes including The production of most types of electric lamps, vacuum tubes, and CRTs where the device is either left evacuated or re-filled with a specific gas or gas mixture, Semiconductor processing, notably ion implantation and sputter deposition.
Vacuum reference tube is use to check or set calibration. It is used to calibrate vacuum gauges accurately. By connecting the reference tube to the instruments gauge tube cord, a fixed reading is indicated on the instruments dial face. If the reading is not consistent with the correct reading as marked on the reference tube, the instrument is adjusted to the proper reading and bringing the instrument to correct calibration.
Vacuum relief valve is a direct loaded safety valve in which the loading due to the vacuum underneath the valve disc is opposed by the compression of a spring. When the valve opens at its set pressure (or set vacuum in the case), air is admitted to prevent the design vacuum being exceeded. The vacuum relief is frequently more convenient and economic to provide a combined safety valve, which will open in the case of excessive pressure or vacuum.