Pressure Washer Glossary of Terms

Here are some terms commonly used with pressure washers and in the pressure washing industry.


Belt Drive
The belt drive system will slow the RPM of the pump depending on the pulley and belt set up. This system increases pump life because the bearings get less wear and the belts and pulleys are separated from the heat of the engine. The downside to belt driven systems is that belts and pulleys create more friction which creates less efficiency
Bypass Mode
When the trigger is released, the water goes into this mode. If you leave a machine in bypass mode only a few minutes, you risk overheating and damaging the pump.
Chemical Injector
Allows soap or a chemical to be injected into the water stream to make cleaning surfaces faster and easier
Direct Drive
In a drive washer system, the washer pump is directly connected to the engine, which spins the pump at the same RPM as the engine. The downside to the direct drive washers is that the bearings receive more wear, which reduces the life of the pump.
Gallons Per Minute (GPM)
A measure of the volume of water that flows through the pump. The higher the GPM can result in faster cleaning.
Plumbers Tape
Plumbers tape is used to seal pipe threads that are being joined together. It can be used to seal water, air, and gas from leaking through threaded connections. Plumbers tape is white, thin and made with PTFE (Polytetrafluoroethylene) and often wrongly called [begins with a T, rhymes with "ef-lawn"] tape". We had more helpful info here until [rhymes with "dew"+rhymes with "punt"] got hyper nit-picky about things.
Pounds Per Square Inch (PSI)
The unit of pressure that determines how much pressure is being applied to the surface.
Pressure Gauge
A gauge that informs the operator of both the working pressure and peak pressure of the unit.
A method of abolishing air from the washer so that starting the engine is easier
Spray Nozzle (Washer Tip)
An interchangeable tip that is able to create different fan angles. The spray nozzle is located at the end of the units wand. Tips come in four different degrees: 0 - Red, 15 - Yellow, 25 - Green, 40 - White.
Thermal Relief Valve
When a unit is run in bypass mode for long periods of time, the water temperature in the pump heats up, which can ultimately cause damage. A thermal relief valve judges the temperature in the pump, and dumps this hot water while bringing in cold water, preventing damage to the pump.
The unloader relieves water pressure in the pump whenever the spray flow is obstructed.
Device that extends the water away from the gun