Rosenbauer FOX Betriebsanleitung Seite 16

FOX
© 1996
79
F
C
Priming pump - method of operation:
The priming pump which is mounted on the bearing block of the centrifugal pump is driven by a V-belt (A).
A spring loaded tension pulley (B) places tension on the V-belt (A).
The micro switch (C) limits the engine speed to 4000 rpm during priming operation because the priming
performance will decrease at higher speed range. As soon as a pressure of approx. 1.5 bar (21 psi) is reached,
the pressure created by the pump moves out the piston-rod of the cylinder (D) and pushes the tension pulley
back automatically. When the tension pulley releases the microswitch (C), the engine speed is controlled by
the position of the throttle lever, regardless of the 4000 rpm limit.
The priming pump must be disengaged manually when operating the unit in hydrant mode or pressure below
2 bar by using lever (Z9), which is connected to the tension pulley. Simultaneously, the valve (F) closes
automatically, if the feed pressure of the pump exceeds 2 bar (29 psi). If necessary, the valve (F) can be closed
manually by using handle (79).
Computing maximum lift
E
Lift is measured from the surface of the static source to the
centerline of the pump. The height of possible lift is not affected by
the angle of the intake hose, but it depends on the vacuum that the
pump (priming pump) can produce and by the atmospheric pres-
sure.
Theoretically, at sea level a pump can lift water 10 m (33.8 feet).
A perfect vacuum is impossible with a fire pump and there will be
loss due to friction, thus the maximum lift is nearer to 6-7.6 m ( 20-
25 feet).
The height that water can be liftted decreases with altitude by
about 0.3 m (1 foot) for each 300 m (1000 feet) of elevation.
A
The weather also affects drafting, but to a smaller degree.
Z9
Priming system
The priming pump serves to deaerate the centrifugal pump and
suck-in the water (drafting).
The priming pump is an automatically controlled double-acting
piston pump. It can be disengaged in hydrant mode to avoid
damages due to high feed pressure, also for operating the pump
below 2 bar to prevent running priming pump.
The priming pump is made of corrosion resistant light alloy.
The piston is provided with sealing rings and piston rings and is
driven through a ball bearing mounted eccentic shaft by means of
B D
a sliding pad.
The moving parts, lubricated with oil, suction and pressure valves,
are centrally arranged in the cylinder heads (valve covers).
15.03.1996 / PT / Rev.02
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Technische Beschreibung
Technical Description