Frequency Response: Diaphragm Pressure Transducers

FREQUENCY RESPONSE

In order to faithfully respond to dynamic pressures, the resonant frequency of the diaphragm must be considerably higher than the highest applied frequency. Depending strongly upon the degree of damping in the diaphragm strain gage assembly and in the fluid in contact with the diaphragm, the resonant frequency should be at least three to five times as high as the highest applied frequency. The subject of proper design for accurate dynamic response is too complex and extensive to be included here. However, for transducers subject to high frequencies or to sharp pressure wave fronts involving high-frequency components, careful consideration must be given to frequency response, both in terms of amplitude and phase-shift.

For reference purposes only, and subject to the assumptions listed earlier, the undamped resonant frequency of a rigidly clamped diaphragm can be expressed using U.S. Customary Units as follows:

(6)

where: g = Acceleration of gravity, 386.4 in/sec ²

= Weight density, lbs/in ³

(continued...)

Page 8 of 12