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7.1 High pressure pump
An unloader (recycling valve) and a safety
valve are located on the pressure side of the
high pressure pump. The unloader recirculates
the water to the suction side of the pump when
the spray handle is closed or if a nozzle is
blocked. The safety valve is adjusted to approx.
25 bar (360 psi) above the working pressure.
The high pressure pump should not run idle for
more than 5 min., since the water inside the
pump gets hot while it is recirculating. The
unloader ensures there is no pressure in the
pump when the engine is stopped. The unloader
and safety valve are adjusted and sealed at the
factory. DO NOT attempt to change this
adjustment.
7.2 Burner system
The burner is controlled by electronic circuits
which include a thermostat, flow switches to
evaluate water flow and a sensor to monitor the
flame. Water temperature is regulated by the
thermostat. Flow switches ensure there is
water flowing through the machine before
allowing the burner to light. These devices are
connected to a printed circuit board which
activates a magnetic solenoid valve on the fuel
pump to supply or stop fuel flow to the burner.
There are two flow switches installed, for
additional safety and protection of the burner
coil. The circuit board ensures that they agree
before allowing fuel to flow to the burner. The
flame sensor is a separate circuit which stops
the machine if there is no flame in the burner in
hot water or steam mode.
It is important for the life of the fuel pump, that
the machine is not allowed to run in the hot
water or cold water mode, with empty fuel tank.
If the burner stops working unexpectedly,
check the fuel level in the tank and refill it if
necessary.
7.3 Diesel engine
A description and operating/maintenance
instructions for the Ruggerini engine will be
found in the Ruggerini manual provided with the
CONTRACTOR DIESEL. Please read this
before starting up. The throttle limit of the engine
has been adjusted by ALTO, so that the max.
number of revolutions corresponds to the max.
pressure of the pump. The adjustment is
sealed. This adjustment must not be changed.
42
Functional description
7.4 Spray lance
The double spray lance is fitted with 2 nozzles,
a high pressure nozzle and a low pressure
nozzle. When the pressure adjustment valve
(pos. 27) is completely closed only the high
pressure nozzle is used. Both the high pres-
sure nozzle and the low pressure nozzle are
used when the pressure adjustment valve is
opened. Nozzles with smaller orifice size (0)
than described in section 5.0 must not be
mounted on the lance.
EN
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