Inspection and Maintenance Procedures Inspection and Maintenance
IMP–10
Use of a mercury manometer is not recommended. Mercury will react destructively with copper and
brass in system components under certain conditions, if it were accidentally injected into the cooling
water system.
Flow Versus Pressure Drop
Water (or coolant) flow versus pressure drop curves may be prepared for any orifice* size by using the
equation:
Q + 300KA
P
Ǹ
+ gpm
where the symbols are as follows:
B +
Do (orifice)
Di
(pipe I.D.)
K +
C
d
1 * B
4
Ǹ
P + PSI (orifice)
A + AREA OF ORIFICE + (IN)
2
+ WATER DENSITY LBń(FT)
3
C
d
+ ORIFICE DISCHARGE COEFFICIENT
The flow coefficient K for flange taps is determined experimentally; therefore, it may be extracted from
tables available in several references.*
Water Tank
Examine the internal surface of the tank for cleanliness and the presence of algae or foreign matter. If
water leaks consistently from the tank fill opening with little change in ambient conditions, check the
pressure cap for the proper opening pressure setting. Also check for a missing cap gasket, poor gasket
surface, or damaged filler neck sealing surface. The pressure setting should be within
± 15% of the pres-
sure cap rating. The vacuum valve should open between zero psig (0 bars) and 1/2 psi (0.035 bars) vacu-
um. Check for leakage at the tank cover and gasket.
Cooling Water Fans
If the turbine is equipped with an off base cooling water module, annually check the cooling water
radiator fans, the fan housings and the motors for cleanliness, vibration, noise, blade damage, rust and
corrosion, and mounting bolt security. Make sure there are no obstructions in the inlet and outlet duct
work and that screens are clean. For detailed information on the inspection, maintenance disassembly
and reassembly of the fan, refer to the instructions under the Cooling Water System tab in the Service
Manual.
*ASME publication “Fluid Meters — Their Theory and Application” (Fifth Edition). Also, Crane Co., Technical Paper No. 410 “Flow of Fluids
Through Valves, Fittings and Pipe”.
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