Differential pressure gauges are widely used in the industrial field, and they are usually good solutions to some problems. Many friends are curious about how does a differential pressure gauge work. In fact, knowing the working principle of a differential pressure gauge is as simple as knowing what a differential pressure is.

The pressure difference or DP or ∆p is simply the difference between two applied pressures. For example, if the pressure at point A is equal to 100 psi and the pressure at point B is equal to 60 psi, the pressure difference is 40 psi (100 psi – 60 psi).

A differential pressure gauge is a visual indicator designed to measure and illustrate the difference between two pressure points in a process system. The pressure gauge usually has two air inlets, each of which is connected to a monitored pressure point. The differential pressure gauge simplifies the process by finding the difference between points. Without this differential pressure gauge, the operator or control system will need to observe two separate pressure gauges and determine the difference in readings.

In many industrial process systems, filtration is an important part of efficient operation. The differential pressure gauge is also very important because it can be used to detect contaminated or clogged filters. How does it work? When the filter collects foreign matter, the pressure before the filter builds up. The more the filter is blocked by particles, the greater the pressure difference increases. Once the pressure difference reaches its maximum value, the operator knows that the filter needs to be replaced.

Sealed storage tanks usually have a normal pressure air cushion above the liquid. The pressure of the air cushion increases the hydrostatic pressure generated by the content water column. This pressure makes it difficult to obtain accurate liquid level measurements using conventional pressure gauges, which is why differential pressure gauges work more effectively in this application. The differential pressure gauge measures the difference between the gas pressure and the total pressure and converts it into a true level reading. Differential pressure gauges can also be used in production wells and injection wells to measure the difference between reservoir pressure and bottom hole pressure or between injection pressure and average reservoir pressure.

Differential pressure gauges are also used to measure liquid flow in pipes. Orifice plates, venturi tubes, or flow nozzles are usually used to reduce the internal diameter of the pipe. The differential pressure gauge measures the flow by finding the pressure difference before and after the orifice. The differential pressure gauge is an easy way to visually display the process flow.