37
Figure 7-4
Setting Raw Water Flow Rate
The proper amount of raw water flow thru the engine is of the utmost importance, and the pressure gauge
value does little to indicate if there is sufficient flow. When the engine is exercised weekly, the amount of raw
water flow exiting the engine should always be checked to verify it does not appear to have diminished.
During initial commissioning of the engine, it is important to correctly set the raw flow rate going thru the
cooling loop. Each Clarke engine model has an Installation and Operation (I&O) Datasheet that provides basic
operating conditions of the engine and most values are given based upon engine speed. You will find this
datasheet in the documentation bag that
is shipped with the engine for your specific Clarke model. This datasheet must be available during
commissioning in order to set the proper minimum raw water flow. With the fire pump flowing 150% of rated
flow, and the Automatic flow line open; verify sufficient raw water flow rate is achieved and that the reading of
the cooling loop pressure gauge does not exceed 60 psi (4 bar). You will need to capture the flow for a specific
amount of time coming out of the heat exchanger and going to a floor drain in order to establish a reasonably
accurate flow rate value. Using a container or bucket of known volume, record the time required to fill the
container and compare to the gpm or L/min value provided on the I&O datasheet. THIS IS CRITICAL FOR
PROPER ENGINE COOLING AT MAXIMUM PUMP LOAD!!
If proper cooling water flow rate is established then no fire pump controller alarm will be triggered to indicate
clogged raw water strainer (low raw water flow).
After verifying raw water flow rate in the Automatic flowline, open the Manual by-pass line shut-off valves, and
then close the Automatic flowline shut-off valves and repeat the above process in order to verify the flowrate
going thru the Manual by-pass line. Note, with Automatic flowline closed the controller low raw water flow alarm
may be present , this is normal. Once this is completed; close the Manual by-pass shut-off valves and open the
Automatic flowline shut-off valves to restore conditions back to normal.
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