(55) Accurate Pressure Measurement

07052020, 12:14 PM
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(55) Accurate Pressure Measurement
An extract from An Investigation Into the Required Equipment and Procedures for the Accurate Measurement of Pressure in Hydraulic Fluid Power Systems, The Fluid Power Institute (Milwaukee School of Engineering), ADA244 165 (U.S.AR. M&ER&R), May 1976, 139 pgs.
" 1.2.1.3.1 Snubber Equation Derivation Using the laboratory data obtained in Section 1.2.1.1, characteristic equations for various degrees of snubbing (i.e., 20°, 25°, and 10°), were obtained. The PQ characteristic, in general, for the orifice can be shown to be the following: … The above equation closely resembles the equation of a straight line: … A simple leastsquares curvefit can now be employed to determine n and log₁₀ K. Actual calculations for these values were performed using HP55 programmable calculator and the program given below … page 22 1.2.1.3.2 Hydlraulic Gauge Capacitance Equation It can be shown that the pressurevolume relationship for the bourdon tube pressure gauge is: … The hydraulic capacitance is defined as the rate of change of volume with respect to pressure. That is, … Applying the derivative to the original equation gives … Rearrangement of the above equation results in: … which resembles the equation of a straight line … The calculations necessary to obtain the leastsquare's fit were again performed on a programable HP55 calculator using the program below … page 22 " BEST! SlideRule 

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