Principle
A pressure sensor is made out a piezoresister Wheatstone bridge. The pressure is applied to the diaphragm and passes through the silicon oil onto the Wheatstone bridge. When the pressure acts directly on the front face of diaphragm, the Wheatstone bridge will create a different voltage. This voltage difference can then be amplified to obtain a current signal of 4-20mA. After connecting this current output to a meter, we can scale the meter to read the level of the applied liquid in a container or a vessel.
