Pressure Sensor-Surge Pressure

There are many different types of pressure sensors and the manufacturer of the sensor you are considering is the best source to answer your question.

Frequency is defined as "cycles per second" and is usually measured in Hertz [Hz]. In the case of an electronic pressure sensor, frequency most likely refers to the number of pressure 'samples' that the sensor takes in a given period of time.

Frequency - Wikipedia, the free encyclopedia

Maybe it refers to sampling rate.

Don't you have any instrumentation people there?

Frequency, as it applies to pressure sensors, refers to the frequency response of the sensor. This is the frequency at which the output signal is down 3db from lower frequencies.

When using a pressure sensor to capture peak pressures, you will want to have a sensor with as high of a frequency response as possible. Also, if you have some idea of what the pressure hammer waveform will be, you can perform a fourier analysis on it to calculate its frequency components.

Keep in mind that the output signal of the sensor must then be captured at a high enough rate that the water hammer can be accurately characterized. You will want to sample the signal at a minimum of twice the frequency of the sensor (Nyquist criteria), although five to ten times will give you a much better picture of the pressures you're measuring.

For pressure sensors (but not only) the frequency is in general the own mechanical frequency of the sensing element. It has NOTHING to do with sampling since sampling is related to the acquisition structure. This frequency is important since in case of dynamical measurements (and those are not only related to water hammer) the major error source can be the the low-pass filter effect of the sensor it self. In general it is considered that the own frequency MUST be at least 3x maximal appearing frequency in the measured process. This has nothing to do with the Nyquist criterion which is related to the signal acquisition: it means that a sinus can be recognized if at least 3 values are sampled per half wave. If the sensor is low in frequency you can sample even with 10 values per half wave but the result will be wrong since the sensor was MECHANICALLY not able to follow the pressure variation.

One has to look at ALL components of the measuring chain and as far as possible not mix effects and sources.