How Does Temperature Affect Pressure Sensors?

Like any physical measurement system, pressure sensors are subject to errors caused by temperature variations, and these must be considered in sensor selection.

In applications with wide temperature variations such as down-hole drilling, automobile manifold pressure monitoring or autoclaves, the user must determine the maximum and minimum temperatures within which the sensor has to operate and find a unit that is compensated for these extremes.

If accuracy is an important parameter for the application, then temperature errors assume a larger importance, as accuracy will change significantly due to small changes in temperature.

The temperature range of a pressure sensor is normally specified in two ways: the operating temperature range and the compensated temperature range.

Operating temperature range

This is the temperature range over which the sensor will operate without damage. It is specified between a minimum and maximum temperature, for example -20 to +50°C.

Compensated temperature range

This is the temperature range over which the sensor will function within a set specification defined by thermal effects on zero and thermal effects on span. And as both these effects exist concurrently, the total effect on the output is the sum of the two individual effects.

It is important to remember that the temperature-compensation circuit is mounted inside the body of the sensor. Therefore, to ensure proper compensation the complete front assembly of the sensor must be heated or cooled.

If the sensor is subjected to a heat shock, either via the pressure media or from the surrounding the environment, large errors are possible that can exceed the specification. However, this effect does depend on the sensor’s construction, the technology used and the purpose for which the sensor has been designed.

Note

Many of today’s pressure sensor specifications also quote a media temperature range. While this temperature rating is valid for the media being measured, the body of the sensor must be in a cooler area (or at least the housing or the sensor much be kept cool).

Read more: Index to all of our Technical Notes on Pressure

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