#WishIknew – How does a pressure transmitter work?


When you have a question about process automation that needs a short answer, let us know with #WishIknew and @Visaya! We’ll reply with a #WishIknew post. It’ll give a quick explanation, then some related articles, videos, or reviews if you want to know more.

I wish I knew how a pressure transmitter works!

Pressure transmitters are simple devices based on a simple principle. And you can use them to measure more than pressure, like level and flow. But how do they work? Let’s see.

Here you have electronics connected to a sensor. You can find many types of sensors on the market – capacitive, piezo-electric, resonant silicon, and more. I’ll tell you how it works using the capacitive sensor as an example. It’s the most common, although that doesn’t make it the best.pressure transmitter that can measure flow

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 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

As I said before, pressure transmitters can measure more than pressure. Using different primary elements, you can measure flow through the differential of pressure.

You can also measure the level of closed and open tanks. For that, you can use a transmitter with differential, absolute, or gauge pressure. I’ve spoken more about those differences in this article here.

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.

This article is part of our Book of Instrumentation. To learn more about Process Instrumentation check out the whole book here.

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