Frank FH 711 DMP Operating Instructions Manual page 24

3.2.2 Water and chemical systems
The incoming water from the main water supply flows past the float valve into thewater inlet
tank. The water is then pumped by the high-pressure pump through the water heater and
supplied under pressure to the safety spray lance. The flat jet nozzle of the spray lance
creates a powerful fan-shaped high-pressure jet. Cleaning agents can be added via a dosing
valve and a solenoid valve.
3.2.3 Safety spray lance with mechanical spray gun
The mechanical spray gun permits operation of the unit only when the safety control lever
is operated. Actuating the lever will open the spray gun. When the lever is released the
spray gun is closed, thus preventing further water emerging from the spray lance. Closing
the spray gun during the operation will result in a delayed machine shutdown via a pressure
switch and an electronic shutdown timer. Actuating the gun lever again will restart the ma-
chine via a second pressure switch without delay - after the pressure has fallen below 20 bar.
TThe spray gun is a safety device. Replacements and repairs may only be carried
out by qualified presonnel. In case of replacement, only parts authorized by the
manufacturer may be used.
3.2.4 Shutdown delay, System "Variostop"
An electronic shutdown timer permits setting a minimum delay of 2 seconds up to a maxi-
mum of 60 seconds.
Time settings may only be peformed by qualified personnel with the machine dis-
connected from the mains supply.
3.2.5 Burner delay element
The electronic time delay element within the switch box causes the delayed starting of the oil
burner. The time delay is approx. 4 seconds. The delayed opening of the oil burner solenoid
valve prevents ignition from taking place in the event of air starvation which could cause
smoking.
3.2.6 Protective ON/OFF motor switch
Actuating the motor switch will start or stop the machine. The motor switch has been designed
as a protective motor switch and protects the high-pressure pump drive motor against
overload. In case of overload conditions, the entire machine will be cut out automatically.
3.2.7 Overflow safety valve
The overflow safety valve protects the high-pressure pump from excessive high pressure
and has been designed in a way that it cannot be set above the maximum permissible oper-
ating pressure. By operating the handwheel two different operating stages can be set. The
limiting nuts on the handwheels have been paint-sealed.
Replacements and repairs may only be carried out by qualified personnel. In case of
replacement, only parts authorized by the manufacturer may beused.
Pressure and flow rate regulation: only operating stages HD (hot water high pressure) and
D (steam) are regular and permissible operating stages. For changing the operating stage,
a changeover is necessary which may only be carried out when the machine is switched off
and depressurized.
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