The response time behaviour of pressure sensors: How may be 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, like the response time, settling time or rise time in specifications or data sheets. In general, it might be assumed that the response time is defined as the interval required by the output signal of a pressure sensor to show a big change in the applied pressure. Of greatest practical relevance may be 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). For the sake of simplicity, the picture only shows a perfect situation.
The truth is, the response time of pressure sensors contains further influencing factors, such as for example dead time or overshoot, because of their particular constructive setups. Common data sheet specifications on the response time usually contain additional data concerning the test conditions applied, such as T90 or 10 ? 90% (used below for exemplary calculation). These details defines the interval in which a steplike change in the applied pressure from 10 to 90% of the entire span (e.g. from 60 to 540 bar for a 0 ? 600 bar pressure sensor) leads to a defined change in output signal of 10 to 90% of the ultimate value (e.g. from 1 to 9 V at an output signal of 0?10 V).
The typical design of modern pressure transmitters already allows rise times of ? 2 ms. However, special forms (such as submersible pressure transmitters) may also show clearly higher values of ? Beating on purpose. The basic rule is that in applications with high load cycles, such as for example in mobile hydraulics, short rise times are recommended, whereas in slow applications, such as level measurements by submersible pressure transmitters, long rise times are often advantageous.

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