These are a few terms you may see exploring our website. If you
see a word you don’t recognize, take a look in the glossary.
These terms will help you understand pressure washing lingo.
Adjustable Pressure Regulator
This is a unloader valve that not only unloads the pressure but
also allows you to adjust your operating pressure by just a turn
of a knob on the unloader valve itself. Examples of machines that have this.
Certain pressure washers include a nozzle that can be adjusted to
allow for different angles or spray patterns just by turning your
wrist. These nozzles are for homeowner type machines.
This is a pump used to transform the circular energy of the motor
or engine into a back and forth motion of a pump's pistons. Axial
pumps typically have fewer parts and last only a short period of
Belt Drive Pump
Belt driven pressure washers use pulleys and belts to gear down
the speed of a pump. Your engine turns at 3,750 RPM, Using the pulleys
and belts the pump will be slowed to 1,450 to 1,750 RPM. By using
this type of unit your pump can last up to two times longer than
a direct drive pump.
When you release the trigger your water goes into this mode. If
you leave a machine in bypass mode for longer than two minutes you
risk damaging the pump.
This is a process of starving a pump for water. Air will travel
through the pump and cause it to vibrate. Frequent cavitations will
damage your pump.
Ceramic or Non-ceramic Plungers Pumps
Ceramic plunger have a coating around the plunger giving it more
rigidity. Non ceramic plungers have a shorter life and retain more
heat causing premature failure.
The chemical injector pulls soap or chemical into the water stream
this process only works when you use your low pressure tip with
a larger orifice size. You can inject pressure at high pressure
although you run the risk of causing damage to your pump from the
Direct Drive Pump
On a direct drive pressure washer the pump is bolted straight to
the engine shaft to shaft. Your engine turns at 3450RPM and so does
the pump. Building the machine this way creates a compact machine
although the pump may need more attention in the long run.
Effective Cleaning Units (ECU)
Performance measured by a mathematical formula to determine the
total cleaning units produced by your machine: cleaning units (ECU)
= pressure (PSI) x water volume (GPM).
EZ Start Unloader
EZ Start unloader relieves pressure so starting the engine is much
easier , and causes less damage to the starter on electric start
engines. Also found on electric pressure washers.
GPM (WATER FLOW)
GPM is the scientific abbreviation for water volume or gallons per
minute. When you see a machine that produces a certain GPM it also
requires that same volume on the incoming side of the pump.
Gear Drive Pumps
This is just another means of lower the speed of a pump to make
it last longer. Using a gear box in between the pump and the engine
you can cut speed nearly in half on the pump side.
Ground Fault Current Interrupter (GFCI) protects user from electrocution.
This is a device used in plumbing and maintenance to clear clogged
drain lines, sewer lines, and small culverts. Using high pressure
water through a speacially designed hose and a Jetter nozzle, you
can blast through heavy clogs.
This nozzle comes in sizes that range from 1/8” to ½”
. They have strategically placed orifices that allow them to act
differently in the line being jetted. There are many types of nozzles
available including, laser, ram, corner, and rotary.
Overhead Valve OHV is an efficient internal combustion engine that
runs cooler and helps to reduce emissions.
Overhead Valve Industrial OHVI is an efficient internal combustion
engine that runs cooler and helps to reduce emissions. This is a
more rugged version of the OHV.
Powder coating is painting process that creates a super bond of
the paint and the surface by using heat to bake the paint to the
PSI is the scientific measure for pressure. PSI stands for pound
per square inch. Pressure washers can have a PSI as high as 6000;
however most machines are between 3-4000psi.
Pressure Washer Hose
This is a wire braided hose that can accommodate pressures up to
5000PSI. Hose may be double braided, or single braided. Grey hose
is a non-marking hose; however it may wear out quicker than other
This is a device used to measure both working pressure and peak
pressure depending on where on your machine it is installed. Pressure
gauges are ideal for jobs which require exact pressures.
A method of eliminating air from a pressure washer.
Rotations Per Minute RPM is how many rotations per minute an engine
makes. Most gas engines in the pressure washer industry run 3450 RPM.
A spray nozzle is located on the end of your wand and is interchangeable
to create different angle fans. As you use different nozzles you
will increase or decrease the width of the fan.
Typical Pressure Washing Spray Nozzles
- 0° Spray Tip – RED - This tip is
not recommended for wood applications, its
stream of water is to narrow and concentrated. This tip would
be ideal for concrete, and metal.
- 15° Spray Tip – YELLOW - This tip
is a heavy duty cleaning or stripping tip. You
can use this tip for cleaning concrete, loose paint, and driveways.
- 25° Spray Tip – GREEN - This tip
is for general washing purposes. You will find yourself using
this tip for your deck, siding, and your car.
- 40° Spray Tip – WHITE - This tip
has the least amount of impact. The white tip is great for rinsing,
cleaning out your gutters, and other sensitive jobs.
Thermal Relief Valve
This valve is used to alleviate the over heated water in a pump
when the trigger gun is left in the off position with the engine
and pump running. As the machine continues to run the water in by-pass
mode will heat up causing damage to the pump. The thermal relief
valve will release the water allowing cool water to flow into the
pump preventing any damage.
This gun is used to control the water flow. Once you pull the trigger
you have water let off the water stops. Shop our trigger guns.
The unloader valve allows the water to by-pass in the pump head
when you have the trigger gun in the closed position. This prevents
pressure build up and possible damage to your equipment
A device used to extend the water away from the trigger gun. Your
spray tips will connect to the end of the wand. Wands come in many
lengths and can even be extended up to 24’. Most wands are
made of aluminum; however some telescoping wands may be fiberglass. Shop our wands.
If you were not able to find the answer
you were looking for in this section call Amazing Machinery at 1-800-504-7435
to speak with one of our experienced pressure washing staff members.