The response time behaviour of pressure sensors: How is the response time defined and what’s this is of the rise time?

The response time of pressure sensors is reflected in a lot of varying parameters, including the response time, settling time or rise time in specifications or data sheets. Generally, it could be assumed that the response time means the interval required by the output signal of a pressure sensor to display a change in the applied pressure. Of greatest practical relevance is the so-called rise time. The graphic shows a simplified diagram of a steplike change in pressure (shown in blue) with a time-delayed change in signal of the pressure sensor (shown in red). With regard to simplicity, the picture only shows an ideal situation.
The truth is, the response time of pressure sensors contains further influencing factors, such as dead time or overshoot, because of their particular constructive setups. Common data sheet specifications on the response time usually contain additional data regarding the test conditions applied, such as T90 or 10 ? Mammoth (used below for exemplary calculation). This information defines the interval in which a steplike change in the applied pressure from 10 to 90% of the full span (e.g. from 60 to 540 bar for a 0 ? 600 bar pressure sensor) results in a precise change in output signal of 10 to 90% of the final value (e.g. from 1 to 9 V at an output signal of 0?10 V).
Stop of modern pressure transmitters already allows rise times of ? 2 ms. However, special forms (such as for example submersible pressure transmitters) may also show clearly higher values of ? 100 ms deliberately. The basic rule is that in applications with high load cycles, such as in mobile hydraulics, short rise times are recommended, whereas in slow applications, such as for example level measurements by submersible pressure transmitters, long rise times are usually advantageous.

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