Microsoft Excel Worksheet
Pressure Difference Measurement
The Lodge Stressmeter makes use of a specially-developed system for measuring small pressure differences Dp in the presence of large ambient pressures p. The attached graph of some recent data gives direct readings from a pressure difference transducer, located in a pressurized Parr bomb, when a pressure difference of about 0.1
psi is switched on and off three times. It can be seen that, by averaging out the noise, values of Dp down to about 0.004 psi can be resolved. This corresponds to a value of 2 x10^(-6) for the common mode suppression ratio Dp/p.

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