The liquid level sensor (static pressure level gauge/liquid level transmitter/liquid level sensor/water level sensor) is a kind of pressure sensor for measuring liquid level. Static pressure input type liquid level transmitter (liquid level gauge) is based on the principle that the static pressure of the measured liquid is proportional to the height of the liquid, and adopts advanced isolated diffusion silicon sensor or ceramic capacitance pressure sensor abroad to convert the static pressure into an electrical signal, and then after temperature compensation and linear correction, it is converted into a standard electrical signal (generally 4 ~ 20ma/650).