Level transmitter is used to measure the level of a liquid or bulk solid material within a specified space and to provide electrical output about these measurements that are proportional to the input level. This is used to measure level based on either a point level or continuous level readings. Point level transmitters provide output when a specific level measurement is reached. This is generally in the form of an audible alarm or an electrical charge to actuate a switch. This can be integrated together to give a stepped version of continuous level. They can operate through a wide range of temperatures, pressures, vapor gas mixtures, and process conditions. Some of the transmitters have air bubblers, which use a constant volumetric rate of gas flow fed through a bubble tube submerged in a liquid. Some use pressure membrane as a detector. These devices have a pressure sensitive switch with pressure transmitted to an internal sensor via an organic, or thin metal and membrane. Its ambient operating temp is +5°C bis 70°C. The sensor measures the pressure and the data is transmitted by a 4 to 20 mA output signal.