# 7.29 Orifice Flow Rate Calculation

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In [1]:

from fluids.units import *
from thermo.units import Chemical

P1 = 2*u.bar # The full set of equations requires actual pressures not just the pressure difference, so an initial pressure of 2 bar is assumed.
P2 = P1 -  17*u.kPa
taps = 'D'
meter_type = 'ISO 5167 orifice'
Do = 50*u.mm

NPS, D, _, t_pipe = nearest_pipe(Do=80*u.mm, schedule=80)

D

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Out[1]:

0.07366 meter

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In [2]:

water = Chemical('water', T=15*u.degC, P=P1)
rho = water.rho
mu = water.mu
k = water.isentropic_exponent
rho, mu, k

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Out[2]:

(<Quantity(999.149354395, 'kilogram / meter ** 3')>,
<Quantity(0.00113751328021, 'pascal * second')>,
<Quantity(1.32952939555, 'dimensionless')>)

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In [3]:

m = differential_pressure_meter_solver(D=D, D2=Do, P1=P1, P2=P2, rho=rho, mu=mu, k=k, meter_type=meter_type, taps=taps)
print(m)
Q = m/rho
print(Q.to('L/min'))

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7.70427741167 kilogram / second
462.650196056 liter / minute

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The answer given in TP410M is 478 gallons/minute; however the errata specifies this value is in units of liters/minute insteead.

This calculation matches their result well, given they did not include expansivity in their calculations and read a value of C from a graph.

A calculator at flow of fluids, which also does not include expansivity, gives an answer of 476.777 L/min, along with 7.93916 kg/s (http://www.flowoffluids.com/calculators/flow-through-orifices.aspx).