Calculation of Orifice Coefficient Using ISO 5167 (U.S. units)

Inputs Calculations

12 in 1 ft

5 in 0.4167 ft

Measured pressure 0.1364

1.2

0.4

1.94

0.000027 Orifice Coeff., C** 0.601

Upstream Press. Measured pressure

0.0833 ft 172.8

Downstr. Press. Pipe Flow

0.0833 ft Rate, Q 1.11 cfs

Reynolds No., Re 585,500 Pipe Velocity, V 8.15 ft/sec

(assumed value)*

Reynolds

Number, Re 585,459

(calculated value)

* This is an iterative calculation. Assume a value for Re to start. Then replace the assumed Re

with the calculated value of Re as many times as necessary until they are essentially the same.

Pipe Diam, D1

Pipe Diam, D1

Orifice Diam., D2

Orifice Diam., D2

Orifice Area, A2 ft2

diff., P1 - P

2 (psi) lb/in2

Diam. Ratio,

Fluid Density, slugs/ft3 (= D2/D

1)

Fluid Viscos., lb-sec/ft2

Tap Loc., L1 diff., P

1 - P

2 (psf) lb/ft2

Tap Loc., L2

** C = 0.5959 + 0.0312 β2.1 - 0.1840 β8 + 0.0029 β2.5(106/Re)0.75

+ 0.0900(L1/D)[β4/(1 - β4)] - 0.0337(L

2/D)β3

14

15 30 cfsroughness, n =

Discharge, Q =

0.0000roughness, n =