Pressure washer terminology, Pressure washer operating features – Porter-Cable PCH3740 User Manual
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PRESSURE WASHER
TERMINOLOGY
PSI: Pounds per Square Inch. The
unit of measure for water pressure.
Also used for air pressure, hydraulic
pressure, etc.
GPM: Gallons Per Minute. The unit of
measure for the flow rate of water.
CU: Cleaning Units. GPM multiplied
by PSI. GPM x PSI = CU
Bypass Mode: Allows water to
re-circulate within pump when the
gun trigger is not pulled.
Allowing the unit to
run for more than
two minutes without the gun trigger
pulled could cause overheating and
damage to the pump.
Thermal Relief Valve:
When the temperature
inside the pump rises
too high the valve will
open and release a
gush of water in an
effort to lower the
temperature inside the pump. The
valve will then close.
Chemical Injection System: Mixes
cleaners or cleaning solvents with
the water to improve cleaning
effectiveness.
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.
PRESSURE WASHER
OPERATING FEATURES
PRESSURE ADJUSTMENTS
The pressure setting is preset at the
factory to achieve optimum pressure
and cleaning. If you need to lower the
pressure, it can be accomplished by
these methods.
1. Back away from the surface
to be cleaned. The further away
you are, the less the pressure will
be on the surface to be cleaned.
2. Change to the 40º nozzle -
(white) this nozzle delivers a less
powerful stream of water and a
wider spray pattern.
DO NOT attempt
to increase pump
pressure. A higher pressure setting
than the factory set pressure may
damage pump.
3. Adjust the
pressure reg-
ulator on the
pump. Turn
the pressure
regulator knob
counterclock-
wise to lower
pressure. Refer
to the illustrations to identify your
pressure regulator. Once you
have finished using your pressure
washer, return the pressure reg-
ulator to its original position by
turning it clockwise.
DO NOT try to turn
pressure regulator
knob past the built-in stop or
damage to pump will result.
Pressure
Regulator
Knob
Thermal
Relief
Valve