Differential Pressure Transmitter

Differential Pressure Transmitter

First, we discuss Differential pressure is the difference in pressure at two distinct points in the same fluid/gas. 

                                                    Δp=p1-p2

          where Δp is Differential pressure,p1&p2 is high and low pressure

It is an instrument that measures the pressure difference between two pressure points Low-side(L) and High-side(H) of process line fluids then converts it into an electrical signal it is called a differential pressure transmitter. A differential pressure transmitter is the same as a gauge pressure transmitter.

Working Principal Of Differential Transmitter

Its design work on the principle of differential capacitance. In this design, the sensing element is a rigid metal diaphragm located equidistant between two stationary metal surfaces, comprising three plates for a complementary pair of capacitors. An electrically insulating fill fluid (usually a liquid silicone compound) transfers motion from the isolating diaphragms to the sensing diaphragm, and also doubles as an effective dielectric for the two capacitors. Any difference of pressure across the cell causes the diaphragm to flex in the direction of least pressure. The sensing diaphragm is a precision-manufactured spring element, meaning that its displacement is a predictable function of applied force. So the diaphragm’s secondary function as one plate of two capacitors provides a convenient method for measuring displacement. Since capacitance between conductors is inversely proportional to the distance separating them, capacitance on the low-pressure side will increase while capacitance on the high-pressure side will decrease.

Application Of Differential Pressure Transmitter

• Oil and Gas flow measurement onshore and offshore.
• Water treatment plants. It is widely used for monitoring the filters of plants.
• Pump control monitoring.
• Remote sensing of Heating Systems like Steam or Hot Water.

What is Gauge Pressure

It is the pressure difference between the measured fluid and the atmospheric pressure.

A Differential Pressure transmitter can be used as a gauge pressure transmitter if the low side port is open as a reference point means atmospheric pressure.

FAQ

what is DPT?

Differential Pressure (DPT)  measures the difference between two pressures.
What is the purpose of differential pressure?

It is used to determine fluid flow rate in a pipeline and differential pressure measurement.

How does differential pressure relate to flow?

According to Bernoulli's law tells us that the flow rate is proportional to the square root of differential pressure.

What is the range of differential pressure transmitters?

The differential pressure transmitters are available in market various companies. The measurement ranges available from 0 bar-30 bar.

What is the maximum differential pressure allowed?

The maximum differential pressure across a filter with clean elements is 5 psig or 0.34 bar at normal operating temperature.