Where:
H=
height (the elevation difference)
SG =
specific gravity before rising to the higher power.
2,31 =
conversion constant (1 psi = 2.3 1 feet of head of water at 70 degrees F.)
Example:
Height (800 to 850 feet) 50 feet (uphill elevation difference).
Specific Gravity (58 degrees API converts to) 0.7467
NOTE: With the pressure for elevation we can adjust the pressure reading taken from the two gages on the
pipeline.
Example: Pressure gage readings; 225 and 195 psi, the difference between the two = 30 psi.
(1) To correct the pressure take the pressure difference from the gages which equals 30 psi and
subtract the pressure determined from the elevation which is; 16.
(2) With a gage pressure of 30 psi subtract 16 psi this gives an answer of 14 psi. The figure of 14 is
used in the Hazen Williams equation for "p".
30 psi - 16 psi = 14 psi.
NOTE: To further emphasize the elevation and pressure.
Pressure gage reading: 175 psi and 165 psi = 10 psi.
Elevation: 745 and (downstream) 742 = 3 feet
SG.:
0.7467
Example: 10 psi - 1 psi = 9 psi used in the formula this has corrected for the gage reading and not for the actual
friction and pressure loss.
QM5200
15-8
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