Pressure transmitters are used to determine the pressure in a vessel or sometimes the level of the vessel. It measures and transmits signal that provides information on these values at specific points in a water system. They provide the information needed to calculate an individual pump's performance or that for a complete pumping system. The differential transmitters are used to measure the hydrostatic level in closed vessels such as hydropneumatic tank. This converts applied pressure to an electrical signal that can be interpreted by a computer or other interpretive device, where it can be used to display or control a process variable.