#WishIknew – What is instrument range?

Calibration

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 what instrument range is!

Here we go again, breaking down all the ranges within an instrument. Just to recap, we have the instrument range, the measuring range, and the calibration range. If you’re following us here at Visaya, you already know calibration range and measuring range. If you haven’t read those #WishIknew posts, then you can take a peek at them afterward.

To the question then. Instrument range is the range where the device can work without damage. Take a pressure transmitter, for example. The vendor site will probably show you the measuring range. However, the instrument range goes beyond that. To find the instrument range, you’ll most likely have to look in the manual.

instrument range
Courtesy of Endress + Hauser

When you dig a bit through the manual, you’ll find a table with the measured variable, in this case pressure. In this table, you should see not only the measuring range but also the maximum working pressure (MWP) and overpressure limit (OPL). Your instrument range will be the sum of all these values. Example time!

Imagine you have an Endress+Hauser PMP71 for absolute pressure that has a measuring range from 0 to 10 bar. The manual shows an MWP higher than the upper range limit, 26.7 bar. You’ll also find an OPL of 40 bar. This means that the instrument range will go from 0 bar to the OPL of 40 bar. Tada!

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Related tags: #WishIknew Calibration Instrument range
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