ES749 Flow Computer
53
Enter the Viscosity coefcient B for the anticipated uid. This
information is needed by the viscosity computation for UVC and for
Reynolds Number calculations.
Note:
Select "SQUARE LAW 16PT" or "LINEAR UVC" in
"FLOWMETER TYPE" to activate this function.
Input:
Number with xed decimal point: 0.000000...1000000
Display: 0.3850
VISCOSITY COEF. B
FLUID DATA
6.7
FLUID DATA
(Continued)
VISCOSITY COEF. B
Computation of Viscosity Coef. A and B
The ow computer solves an equation which computes the viscosity as a function of temperature. Two
parameters must be entered for this calculation to be performed. These are the setup parameters Viscosity
Coef. A and Viscosity Coef. B. A table listing these values for common uids is available from the factory.
Alternately, if your intended uid is not listed, the Viscosity Coef. A and B can be derived from two known
temperature/viscosity pairs. Begin by obtaining this information for you intended uid. Convert these known
points to units of Degrees F and centipoise (cP)
The information is now in a suitable form to compute the Viscosity Coef. A and Viscosity Coef. B using the
following equation based on the uid state.
For a liquid, A and B are computed as follows:
B = (T1 + 459.67) • (T2 + 459.67) • ln [ cP1/cP2]
(T2 + 459.67) - (T1 + 459.67)
A = cP1 .
exp [ B / ( T1 + 459.67) ]
For a gas, A and B are computed as follows:
B = ln [ cP2 / cP1] .
ln [ (T2 +459.67) / (T1 + 459.67)]
A = cP1 .
(T1 + 459.67)
B
NOTE: cS = cP .
Density (in kg/l)
Computation
of Viscosity
Coef. A and B
Enter the % Relative Humidity in the anticipated gas mixture. This
information is needed to more accurately compute the density of a
Humid gas.
nput:
Number with xed decimal point: 0.000000...100.0000
Display: 0.3850
% RELATIVE HUMIDITY
% RELATIVE
HUMIDITY
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