Discharge coefficient 0.9 0.8 0.7 0.2 0.6 0.5 0.4 0.8 0.7 0.6 0.4 0.5 Parameter denotes orifice-to-pipe diameter ratio 0.3 10 100 1000 104 105 Reynolds number through the orifice Pipe wal Pipe wal P1 Differential Pressure Sensor Nut Pipe threads Orifice plate P2 P3 Flange Flange vena contracta (point of maximum constriction -Stud Nut
Consider the attached figure, which includes an illustration of the proposed orifice plate meter. The piping is Nominal 2 in Schedule 40, the orifice plate radius is 0.5″ in, and the plate itself is 0.5″ thick. Flow goes left to right, and to measure pressure losses during flow you will install a differential pressure sensor along the length that will measure the pressure losses. One port for the differential sensor will be placed 4″ upstream (P1) and the other port will be placed 15″ downstream (P3). The distance between the ports will be 19.5″. The ports will be flush with the inner pipe wall so we can assume the pressure measured is the fluid pressure at the wall of the pipe.
1. If the fluid (viscosity = 0.001 Pa·s and density = 1200 kg/m3) flows at 1 gpm, estimate the
pressure lost over the 19.5″ span with the orifice plate in place. Estimate CD from the second figure and do not neglect pipe friction.
2. If the orifice plate is seen as a “fitting,” what is the equivalent length (L/D)e? Base
your calculations on the answer to part 1.
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