Pressure measuring instruments are used to measure the pressure of liquids or gases to maintain the quality standards of the products, for safety concerns of the units, to avoid explosions, to maintain the efficient working of machinery as well as controlling pressure is important for the longevity of the machinery. Measuring pressure ensures safety, optimizes process control, improves energy efficiency and maintains product quality. Industrial pressure transmitters can be used to monitor the pressure of industrial process pressure, measure fluid flow, detect liquid or gas leaks, and measure the fill level of tanks and vessels. A pressure sensor is a device for pressure measurement of gases or liquids. Pressure sensors can alternatively be called pressure transducers, pressure transmitters, pressure senders, pressure indicators, piezometers and manometers, among other names. The types of pressure measuring instruments are divided into liquid column type, elastic type and electric measuring type according to the working principle. The pressure gauge can indicate and record the pressure value, and can be equipped with an alarm or control device. The pressure measured by the instrument includes absolute pressure, atmospheric pressure, positive pressure (usually called gauge pressure), negative pressure (usually called vacuum) and differential pressure.