2-13. FIREFIGHTING OPERATIONS-Continued
Priming the pump may be necessary under some conditions
because of air trapped in the piping. Some fire departments
prime their pumps whenever pumping from water tank as a
(4) Turn RELIEF VALVE lever to ON position and rotate INCREASE/DECREASE knob to obtain
desired pump output pressure.
(5) Open DISCHARGE valves and accelerate engine with THROTTLE control on pump panel to
obtain desired discharge pressure and capacity.
Monitor engine coolant temperature. If the temperature exceeds
210 deg. F (99 deg. C), or the alarm sounds, open ENGINE
COOLER control valve gradually until temperature stabilizes at
200 deg. F (93 deg. C). Failure to heed this caution may cause
f. Operating Foam System.
(1) Engage and prime the pump as described above.
(2) Open eductor valve (labeled WATER on pump panel).
(3) Rotate METERING VALVE handle to desired setting.
(4) Open FOAM valve.
(5) Open desired DISCHARGE valve(s) and nozzle(s).
Residual pressure (as indicated by VACUUM gauge) must not
exceed 10 psi (69 kPa) when pumping from hydrant or relay
during foam operations.