Factors Affecting the Pressure Sensor’s Accuracy

There are many aspects of a pressure sensor that determine whether it is the right choice for a given application. Gauge, absolute or differential, transducer or transmitter, measurement range, fitting style/ size, and absolute maximum ratings such as burst pressure are among the most important. Several pressure sensors may meet the application requirements in these respects. Choosing the right pressure sensor then be guided by considering factors that affect accuracy. Fundamentally, this determines whether the pressure measurements supplied are dependable to inform decisions made by the application.

  • FACTORS AFFECTING ACCURACY

The major sensor characteristics that influence accuracy are temperature coefficients, temperature hysteresis, pressure hysteresis, and non-linearity. Applicable temperature coefficients include temperature-related changes to zero offset, sensitivity, and measurement span.

A datasheet may describe accuracy-related characteristics individually, or as an overall accuracy statement calculated as the root of the sum of squares (RSS) of individual factors.

Note also that accuracy can be expressed as a percentage of the full-scale range, or as a percentage of the reading. Percent of full scale (% F.S) is commonly used, meaning that if the sensor has a full-scale range of 200 psi and is specified as 1% F.S, any reading at any pressure within 0-200 psi is expected to be within ±2 psi of the true pressure.

Alternatively, if the accuracy is stated as a percentage of reading, 1% accuracy at 200 psi would translate to an error of ±2 psi as before.However, at 100 psi the error would be ±1 psi. Clearly the error cannot tend towards zero at 0 psi: at lower reading, the datasheet may quote an absolute figure, say ±0.4 psi, for pressure readings below a stated threshold.

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