37
3.4.7.2 Cooling Loop
Note: Engine may include a cooling loop as an
optional feature and has not been evaluated by UL
as part of a UL Listed fire pump driver.
Clarke cooling loops are FM Approved to meet
standard sizing conditions of 50% blocked wye
strainers, 100degF (38degC) raw water inlet
temperature, 80 psi inlet pressure, and 10 psi
available at the engine outlet.
Figure #19 shows the standard NFPA 20 cooling loop
piping arrangement. The cooling loop consists of an
Automatic flow line with a 12v or 24v solenoid valve
(HSC and ES pump applications only) that is energized
to open anytime the engine is called upon to run from
either the fire pump controller or from the engine
gauge panel.
NOTE: VT type pump applications do not require a
solenoid valve in the Automatic flow line.
The second flow line is called the Manual by-pass line
and it can be opened at any time if for any reason the
engine shows signs of overheating. Each line has two
(quarter turn) shutoff values installed and the normal
position of the shutoff valve is to remain open in the
Automatic flow line and remain closed in the Manual
by-pass flow line.
NOTE: Opening both lines to flow is never a problem
should there be some concern of engine overheat,
especially if there is an emergency situation. The
Manual by-pass line can only be opened by an
operator in the pump room.
The shutoff valves are all identified to show which are
Normally Open (Automatic flow line) and which are
Normally Closed (Manual by-pass flow line). The
shutoff valves are also used to isolate water pressure in
the event of maintenance to pressure regulators,
strainers and solenoid valve. Shut off valves in the
Automatic flow line are provided with lockable
handles for cooling loops that have been tested to FM
requirements.
In each flow line, there is also a pressure regulator.
Each pressure regulator protects the downstream
piping from over-pressurization which includes the
tube side of the engine shell & tube heat exchanger
(and/or CAC) and to control raw water flow rate. The
pressure regulators are set to limit downstream
pressure to 60 psi (4 bar). There is a 0-60 psi (0-4 bar)
pressure gauge installed at the cooling loop outlet, and
prior to the engine heat exchanger (or CAC).
Wye strainers are used to remove debris from the raw
water supply. One strainer is in the Automatic flow
line and the other is in the Manual by-pass flow line.
Note: See section 3.4.7.5 regarding strainer
maintenance.
To Next Page
Loading...
Need help?
General
