tota Chemical Engineering principles, First Year/ Chapter Five Note If fluids 1 and 3 are gases, and fluid 2 is mercury, the density of the gas is so much less than that of mercury that you can ignore the term involving the gas in Equation (5.3) for practical applications. * Can you show for the case in which p1 = P3 = p that the manometer expression reduces to the differential manometer equation: H. W P1-P2 = (p2-p) gde 5.4 Example 5.4 In measuring the flow of fluid in a pipeline as shown in Figure E5.4, a differential manometer was used to determine the pressure difference across the orifice plate. The flow rate was to be calibrated a