TEMPERATURE AND PRESSURE MEASUREMENTSThermodynamicsPabs = Patm + Pgauge(1-9)Pabs = Patm - Pvac(1-10)Patm is atmospheric pressure, which is also called the barometric pressure. Pgauge is the gaugepressure, and Pvac is vacuum. Once again, the following examples relating the various pressureswill be helpful in understanding the idea of gauge versus absolute pressures.Example 1: Pressure RelationshipsHow deep can a diver descend in ocean water (density = 64 lbm/ft3) without damaginghis watch, which will withstand an absolute pressure of 80 psia? (P = density • height)Solution:Assume: Patm= 14.7 psiaPabs= Patm + Pgauge80 psia = 14.7 + PgaugePgauge= (80 - 14.7) = 65.3 psigPgauge= density height = rH(65.3)(144 in2/ft2) = (64 lbm/ft3)HH = (65.3)(144)/(64)H = 146.9 ftHT-01 Page 10 Rev. 0
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business