NATURAL GAS MEASUREMENT
NATURAL GAS MEASUREMENT
(OP)
Hi,
I´m going through a gas flow measurement loop and am a bit confused about the way it´s configured. The flow is measured with an orifice plate (Pd = 8 kg/cm2 man, Td= 37.8°C)and the associated transmitter outputs the flow in ft3/h; the actual pressure and temperature are measured with other instruments and the corresponding units are kg/cm2 man and °C. The flow conditions differ from plate design conditions and the final units for flow must be SCFH. In DCS, the only formula is
F = Fact * SQRT[(Pact/Pd)*(Td/Tact)]
where F = flow in SCFH
Fact = flow in ft3/h from transmitter
Pact,T act= pressure and temperature at actual conditions (6.5 kg/cm2 man, 30°C)
Pd,Td= design pressure and temperature for the orifice plate
However there is no values for standar pressure and temperature (14.73 psia and 60°F) considered in the formula. What would be the right sequence of calculations to get the correct flow in standard conditions?
I´m going through a gas flow measurement loop and am a bit confused about the way it´s configured. The flow is measured with an orifice plate (Pd = 8 kg/cm2 man, Td= 37.8°C)and the associated transmitter outputs the flow in ft3/h; the actual pressure and temperature are measured with other instruments and the corresponding units are kg/cm2 man and °C. The flow conditions differ from plate design conditions and the final units for flow must be SCFH. In DCS, the only formula is
F = Fact * SQRT[(Pact/Pd)*(Td/Tact)]
where F = flow in SCFH
Fact = flow in ft3/h from transmitter
Pact,T act= pressure and temperature at actual conditions (6.5 kg/cm2 man, 30°C)
Pd,Td= design pressure and temperature for the orifice plate
However there is no values for standar pressure and temperature (14.73 psia and 60°F) considered in the formula. What would be the right sequence of calculations to get the correct flow in standard conditions?





RE: NATURAL GAS MEASUREMENT
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat
RE: NATURAL GAS MEASUREMENT
RE: NATURAL GAS MEASUREMENT
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat
RE: NATURAL GAS MEASUREMENT
David,
I think that the formula is for compensating the diference in operating conditions respect the design T and P for orifice plate calculation. If so, then the compensated flow must be "standardized" with the formula that includes the compressibility factor.
RE: NATURAL GAS MEASUREMENT
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat
RE: NATURAL GAS MEASUREMENT