DeVillbiss Air Power Company 3540CWHP - Manual (Page 9)

9 — ENG D20249
OPERATION
OPERATING FEATURES OF YOUR
PRESSURE WASHER
BYPASS MODE
During normal operation water supply is turned on,
engine is running, spray gun trigger is depressed, and
the cold water supply circulates inside the pressure
washer pump allowing pump to maintain a safe
operating temperature. When you release spray gun
trigger and engine is still running, you are in bypass
mode.
When unit is in bypass mode, water circulating inside
the pump begins to heat up. If unit is left in bypass
mode for more than two (2) minutes, the water tem-
perature will rise to a dangerous level and damage
internal components of the pump.
If pressure washer is operated without an adequate
water supply or operated for more than two (2) min-
utes without depressing the spray gun trigger, the
pump will overheat and be seriously damaged. Any
damage to pump due to these causes will not be
covered under warranty.
THERMAL RELIEF VALVE
In an effort to prevent damage, pumps are equipped
with a thermal relief valve. This valve will open when
the temperature inside the pump rises too high. This
valve will then release a gush of water in an effort to
lower the temperature inside the pump. Immediately
after this occurs, the valve will close.
DO NOT allow your unit to operate in
bypass mode for more than two minutes at
any time. Overheating of pump will cause
damage to pump.
PRESSURE ADJUSTMENT
DO NOT attempt to increase pump
pressure. A higher pressure setting than
the factory set pressure will damage pump.
The pressure output of the pump is preset at the
factory to achieve optimum pressure and cleaning. If
you need to lower the pressure, it can be accomplished
by one of these three methods:
1.
Back away from the surface being cleaned. The
farther away you are, the less pressure is delivered
to the surface being cleaned.
2. Adjust the pressure regulator knob on the pump.
a. Turn the pressure regulator knob counter-
clockwise.
b. Once you have finished using your pressure
washer, return the pressure regulator knob to
its original position by turning it clockwise until
it stops.
DO NOT try to turn pressure regulator knob
past the built-in stop or damage to pump
will result
3. Reduce the speed of the gasoline engine (RPM).
Slow engine down and water pressure will go
down with it.
SPRAY NOZZLES
Your pressure washer is equipped with five spray
nozzles. Each nozzle is color coded and delivers a
specific spray pattern for a particular cleaning pur-
pose. The size of the nozzle determines the size of the
fan spray and the pressure out of the nozzle. The 0
O ,
15 O , 25 O , and 40 O nozzles are high pressure nozzles.
The chemical nozzle is a low pressure nozzle.
Pressure
Regulator
Knob
PRESSURE WASHER TERMINOLOGY
PSI: Pounds per Square Inch. The unit of measure
for water pressure. Also used for air pressure, hy-
draulic pressure, etc.
GPM: Gallons Per Minute. The unit of measure for
the flow rate of water through the pressure washer.
CU: Cleaning Units. GPM multiplied by PSI.
Bypass Mode: In Bypass Mode, the pump is recircu-
lating water because the trigger of the spray gun is
not pulled.
Chemical Injection: Feeds cleaning agents into the
pump to mix with the pressurized water and help in
cleaning.
Water Supply: All pressure washers must have a
source of water. The minimum requirements for a
water supply are 20 PSI and 5 gallons per minute.
NOTE: Any supply pressure or delivery rate less than
this will not allow the pressure washer to operate at its
full potential.