A pressure sensor is made up of a piezoresistor Wheatstone bridge. As shown in fig.2, the pressure is applied to the diaphragm and passes through the silicon oil onto the Wheatstone bridge. When the liquid pressure acts directly on the front face of diaphragm, the Wheatstone bridge will creates a differential voltage. This voltage difference will then be amplified to obtain a current signal of 4-20mA. When this current output is connected to an analog meter, we can scale properly to read the level of the applied liquid in a container or a vessel. The formula used here is: P= x H q q Where P is pressure, is pressure constant and H is the level of liquid in a container