The response time behaviour of pressure sensors: How may be the response time defined and what is the definition of the rise time?

The response time of pressure sensors is reflected in a large number of varying parameters, like the response time, settling time or rise amount of time in specifications or data sheets. Generally, it can be assumed that the response time means the interval required by the output signal of a pressure sensor to show a 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). With regard to simplicity, the picture only shows a perfect situation.
In reality, 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 regarding the test conditions applied, such as for example T90 or 10 ? 90% (used below for exemplary calculation). These details defines the interval when 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 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).
The typical design of modern pressure transmitters already allows rise times of ? 2 ms. However, Contrary (such as for example submersible pressure transmitters) could also show clearly higher values of ? 100 ms deliberately. The essential 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 for example level measurements by submersible pressure transmitters, long rise times are usually advantageous.

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