HALE RSD - Drafting and Cavitation Management

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D. Begin shutdown.
Reduce engine speed to idle. 1.
Close discharge valves. 2.
If opened, close bypass line valve(s) or TRV. 3.
Close suction valve. 4.
Place transmission in NEUTRAL. 5.
Disengage PTO. 6.
E. Disconnect all hose connections and stow hoses and strainers.
F. Make all appropriate Maintenance Log entries.
G. Return pump/apparatus to service.
3.4.1 Draft Limiting Factors
The effect of raised water temperatures when pumping from a positive pressure source (hydrant)
is negligible on fire pump performance. But when pumping from draft, elevated water tempera-
ture does have a limiting effect. Water temperatures above 90° F (32° C) will cause a noticeable
decrease in lift when drafting. (See Table 3 for additional losses beyond NFPA rating baseline.)
Another factor that can limit lift is barometric pressures below 29 inHg. It is important to be
aware of environmental conditions when drafting.
Table 3. Additional Losses Beyond NFPA Rating Baseline
Water Temp
° F (° C)
Lift Loss In
Hd Ft (Hd M)
Water Temp
° F (° C)
Lift Loss In
Hd Ft (Hd M)
Water Temp
° F (° C)
Lift Loss In
Hd Ft (Head M)
60 (16) NFPA Baseline 80 (27) 0.6 (0.18) 100 (38) 1.7 (0.52)
70 (21) 0.3 (0.09) 90 (32) 1.1 (0.34) 110 (43) 2.5 (0.76)