What is a Pressure Washer-Pressure Washer Basics That You Should Know

By Power Tools

September 2, 2019

When it comes to removing stubborn stains, paint and debris pressure washer can come in handy.

My neighbors saw me pressure washing my car engine and I say a lot about pressure washing. Most of them have a common question. What is a pressure washer?

what is a pressure washer and its basic

In this article, I will try answering how a pressure washer works. Plus I’ll let you know pressure washer basics too.

Pressure washers use a gas engine or an electric motor to power a pump which forces water at high pressure and speed through nozzles.

The amount of power a pressure washer can deliver is measured in PSI (A unit of pressure expand as Pounds per square inch) and the water flow rate is measured in GPM (Gallons per minute). I have described the water consumption by a pressure washer comparing GPM vs PSI in this article.

Both way you can get an idea of how powerful it is. Generally, pressure washers come in two types electric and gasoline-powered pressure washer.

I have reviewed some pressure washer in this article. Do check those out!

Little information about these two types is given below.

Electric pressure washer

  • PRICE: $90 – $180
  • Best for small jobs as it takes time to finish.
  • PROS: Inexpensive, lightweight, easy storage, quieter than gas, most importantly emission and maintenance-free, can be stored inside.
  • CONS: Need to be near the power source, tougher jobs may take time.

Gasoline Pressure Washer

  • PRICE: $250 – $500
  • Best for tougher jobs like large decks and patios.
  • PROS: Powerful
  • CONS: Noisy, requires tune-ups. Can’t be stored inside because it produces “CARBON MONOXIDE” (CO) known as a silent killer.

Components of a Pressure Washer

Generally, a pressure washer is made of these following components assembled together onto a metal frame:

  1. Electric engine or gasoline engine.
  2. Water inlet.
  3. Water pump.
  4. Wand and nozzle adjustments.
  5. High-pressure hose.

What is a Pressure Washer? (Basic Work Principle)

So, how does pressure washer work? The main principle of its work is “Pascal’s Law” (A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid). A power source helps the pump to execute Pascal’s law. A pressure washer can be departed into two main parts (power source and pump) and many

Power source:

An electric pressure washer consists of an electric motor. The motor is connected to the pump. To run an electric motor, you need to plug in its plug socket. That’s how you power it up.

As you all know, for Starting a gasoline engine you need to turn the switch on and pull the starter rope. In a gasoline engine pressure washer, the engine is used to power up the pump. When you pull starter rope the crankshaft starts rotating. The crankshaft is connected to a piston which moves up and down inside the engine. Thus the ignition process begins.

Flywheel attached to the crankshaft has permanent magnets in it. While rotating past the ignition-coil it creates a magnetic field. The magnetic field induces electricity. It sends voltage to the spark plug.

The intake valve of the cylinder opens and enters fuel and air. Then the engine (Generally, a four-cycle engine completes its work by intake stroke, compression stroke, power stroke, and exhaust stroke) gradually completes all its cycle.

Whether it’s a gasoline engine or electric pressure washer the main work of these two is powering up the pump and pump does the rest.


what is a pressure washer pump with working principle
pressure washer basic working principle

The pump used in a pressure washer may be an axial pump or triplex pump. Both pumps use three plungers to regulate water. The engine crankshaft is connected to the pump. The pump consists of three plungers that operate in the same manner to the piston in the engine.

As each plunger travels upward it draws water through an input check valve, as the plunger travels downward water is forced through an output check valve. Then the water flows through the unloader (An output pipe connected to the gun). When the trigger is pressed the pressurized water through the unloader exits the gun’s nozzle at a high pace. And the cause of pressure here can be explained by Pascal’s law.

When the trigger is released water flow stops. Because of the increased pressure in the unloader, a spring-loaded valve opens the passage in the pump that is connected to the inlet pipe. Then water circulates back to the inlet pipe. This feature helps the engine or the motor to run when the pressure washer is not in use. Otherwise, because of the excess pressure caused by the power source can damage the pipes as well as the pump.

Over time, the water circulating inside the pump becomes hot. If you leave the machine on for a long period without activating the trigger the thermal valve will open and release the hot water so that cooler water can enter the pump.

Some pump has a chemical injection port so that detergent can be mixed with the water stream for deeper cleaning. Some pressure washer has a boiler too for deep cleaning and for freezing winter. Otherwise, you must winterize your pressure washer pump for smooth operation.

A hot pressure washer works on the same principle. So how does water becomes hot? It only has a combusting unit attached inside. This combusting unit makes the water hot before it exits through the nozzle.

This is how a pressure washer works from the inside.

Pressure washer accessories

Considering what you want to clean pressure washer can be equipped accordingly. Like you can attach a surface cleaner to it.

It comes with varieties of pressure wands as well as nozzles. I have described in detail about pressure washer spray wand and selection of nozzle in these articles.

If you want to clean those areas high above the ground then you can rely on extension wand. You can clean your car or other things with a flex wand where your hands may not reach.

What is the difference between a pressure washer and a power washer?

Typically, there is not much difference between these two. The main difference is power washing is done by hot water. Which means power washer can use heated water but a pressure washer use normal water for cleaning.


Well! Pressure washers are quite dangerous. I’m not joking folks, I’m serious. The main problem you may encounter is with nozzles. Generally, nozzles come in four colors. The color indicates interior frame patterns.

Red color indicates 0° (0 degrees) frame and this is quite dangers. While using red nozzle you need to make sure that you don’t dig a hole in your body parts. Remember, water pressure is also used for cutting glass. Yellow indicates 15° frame pattern, green indicates 25° frame pattern and white indicates 40° frame pattern.

For better performance of your pressure washer, you need to know the working purpose of nozzles.

So, read the manual well before using. Otherwise, you may hurt yourself or damage what you are cleaning.

Picture: Karcher