What is DP Transmitter?

                                          What is Differential Pressure Transmitter?

To start off we need to know what are the transmitters?

The transmitter is used to transmit a signal from one place to another. Hence the name Transmitter.

So the differential pressure transmitters are used to transmit the Difference in pressure.

In industries, it is called Dp transmitters or Delta P transmitters. It is user friendly because of its Simplicity.

To study the DP transmitters we should know what is pressure?

The pressure is defined as force per unit area. The SI unit of pressure is Pascal, bar, kg/cm2.

By measuring the pressure difference the following parameters can be measured in an industry.

  • Level
  • Flow
  • Density
Dp transmitters consist of two-chamber cells ( diaphragms) namely the High pressure side and the low-pressure side which sense the pressure of fluid or gas.

Now we'll see how to measure Flow by using DP transmitter,

Dp transmitters consist of primary element and secondary element. The following are the primary elements,
  1. Venturi tube
  2. Orifice plate
  3. Pitot tube

They provide a restriction on the flow for creating a difference in pressure.

Diaphragms are the secondary element that senses the difference in pressure as accurately as possible. Then the difference in pressure is converted into an electronic signal (4 -20 mA) by the capacitive or piezoelectric or piezoresistive method.

The measured flow rate is directly proportional to the square root of the differential pressure. The flow rate can be expressed in both weight rate like kg/hr, tons/hr and volume rate like litres/hr, m3/hr.



  1. Helpful informations. waiting for the next write up !!

  2. Hy there it was a nice explanation.. can you explain how the pressure drop across differential pressure flow meters are detected using DP sensors. What are the sensors involved in it etc.. Thanking you in advance.

  3. Hi Aravindh! Thank you. So the secondary element which is a diaphragm here is used to detect the differential pressure The pressure which acts on the diaphragm is converted to electrical signals using various transducing methods


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