KEP ES749 - 7.4 Computation of the DP Factor

ES749 Flow Computer
101
7.4 Computation of the DP Factor
It is assumed that the user has the printout from a standardized sizing program for the
particular device he will be using. Such standardized printouts list all the necessary
information which the user will then be prompted for by the instrument or diskette.
It is also important that the user select the ow equation to be used and either select or
enter the following items:
Flowmeter Type
The uid type or the uid properties applicable to the uid to be measured
Beta, Meter Exp. Coeff., Inlet Pipe Bore
Reference Conditions of temperature, pressure, Z and calibration temperature
The user is prompted for the following:
mass ow or volume ow or corrected volume ow as indicated by the ow equation
Differential Pressure
Inlet Pressure
Temperature
Density
Isentropic Exponent
The unit then computes the following results corresponding to the user entry conditions and
appropriate methods:
Y
Finally the DP Factor is computed as follows:
Steam Case
mass ow • [1 - Meter Exp.Coeff. • ( Tf - T
cal
)]
DP Factor =
Y • [ 2 • delta P • density]
1/2
Liquid Case
volume • [1 - Meter Exp.Coeff. • ( Tf - T
cal
)]
DP Factor =
2 • delta P
1/2
density
Gas Case
Std.Vol.Flow • ref density • [1 - Meter Exp.Coeff. • ( Tf - T
cal
)]
DP Factor =
Y • [ 2 • delta P • density]
1/2
Application Hint:
The user may reenter this DP Factor multiple times to assist him in assembling the table
points of DP Factor and Reynold's Number necessary to construct a 16 point table for the
meter run.
NOTE: Meter Exp.Coef is (x10
-6
)
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