Pressure Transmitter: Working principle, Applications, and Installation

Pressure transmitter: working principle, applications, and installation

Pressure transmitters are versatile devices based on a simple working principle. Pressure is a primary value in instrumentation and control, and it can also be used to calculate other variables, such as level and flow. There is a wide variety of pressure transmitters in the market for applications with different needs.

Types of pressure
The way we measure pressure in our processes can vary depending on what type of pressure you are interested in. If you only want to know the pressure itself, then a pressure gauge will show you the absolute or gauge pressure. If you want to use pressure to measure a variable such as flow, you need a differential pressure (DP) transmitter.

Pressure force

The pressure transmitter’s working principle
Like other transmitters, a pressure transmitter consists of electronics connected to a sensor. We can find transmitters with many types of pressure sensors on the market – capacitive, piezoelectric, resonant silicon, and more. This article will focus on the capacitive sensor, as it is the most common, although that doesn’t make it the best.

So pressure applied to capacitive cells will produce a change in the capacitance of the sensor. This change will affect the oscillator frequency, and the pressure transmitter will detect this change. Then the transmitter translates this data into a standard output signal that we can read.

Using a local setup or a handheld, you can adjust the transmitter, changing information like the unit, measuring range, and output.


More than just a pressure device
Pressure transmitters can measure more than pressure. Using different primary elements, you can measure flow through with a differential pressure transmitter. You can also measure the level of closed and open tanks. For that, you can use a differential pressure transmitter with differential, absolute, or gauge pressure.

Today we have other principles that work as well or better to measure flow or level. However, you’ll still find pressure devices across many segments, processes, and measurements.

Pressure transmitter installation
You can install a pressure transmitter in all kinds of applications, but all of these take different installations. For example, say you want to measure a level with a differential pressure device. If you have an open tank, then you can install the device on the bottom of the tank using a flange with a filled-sealed container.

If you want to measure flow with a pitot, then you can install the device using a single flange direct to the pitot. Or if you have a steam flow meter with an orifice plate, then you’ll want to install your transmitter remotely with a seal pot between the device and the process.