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 whether I can use capacitance level transmitters in plastic vessels!

Your question makes sense. The principle teaches us that the vessel and the probe act as your capacitor plates and the product as your dielectric. Can’t make a triangle with only two sides, right? But it’s not that black and white! In fact, you have specific conditions to follow for this sensor.

For instance, if you have a medium that conducts higher than 100 micro-siemens per centimeter, then the factory can do the calibration. However, a medium that conducts lower than one micro-siemen requires local calibration. You should also avoid using capacitance level devices between 1 to 100 micro-siemens.

Back to our question. With a plastic vessel, you don’t have the second plate, so you need to create one! Some vendors provide transmitters with two probes to create two capacitor plates. You can also install a concentric tube in the tank to create your second plate. So yes, with a little ingenuity, you can use capacitance level transmitters in plastic vessels!

This video has more on capacitance level devices:

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