On this page we are going to take a look at how petrol pressure washers work. They are complicated machines that help us tremendously in our day to day lives. For most of us we start them up, pull the trigger and off we go. But how do they actually work. On this page we will have a look at the components and see how they fit together to produce a brilliant petrol pressure washer.
To explain how they work it is easiest to go through the components through the system telling one by one how they fit together to build one single machine.
The Inlet Valve
This is connected to the water supply and pushes the water into the pump before it can be fired out at high pressure. Depending on the model that you purchase you can have valves that connect straight to the mains water which gives you plenty of pressure to push the water into the pump or you can have a valve that will take water from a tank. The tanks often gravity feed the water in to the system to give it enough pressure which means the water supply needs to be above the pump to work.
The Petrol Motor
The petrol motor runs at varying revs depending on how much pressure you require from the pressure washer. The motors are usually four stroke petrol engines with good amounts of torque to supply constant and smooth power to the pump. The motor is attached to the pump which pressurizes the water. Generally the more powerful the spray in psi the larger the motor will be. Some of the smaller models that produce around 2500 psi will run off 150 to 200 cc motors whole the bigger more powerful pressure washers that produce the high pressures will require motors of around 400cc which is pretty large.
This is the bit that actually pressurises the water. It is powered by the motor and water is fed in via the inlet valve. Once the water has reached the required pressure the pump will push the water down the pipe towards the gun ready for cleaning. The more powerful the pressure washer the more robust the pump needs to be. The pumps that are fitted to petrol pressure washer need to be able to cope with plenty of pressure. For the mid range models they will usually have a Axial Cam pump that is pretty robust and reliable then the really high pressure commercial petrol pressure washer will have a Triplex pump which is the most reliable pump and the most heavy duty.
Some pumps will push water and pull it from tanks which can be important if you will be using a tank a lot of the time.
The unloader valve plays an important part in keeping the pump and motor running. Once you let go of the trigger the pump will be holding a lot of water at high pressure that it needs to get rid of. This is the job of the unloader valve. It will do one of two things, it will go into bypass mode until the gun is opened up again and the water is flowing or it will unload the water from the pressure washer. The pumps do not have the ability to stop creating the pressure so this stops the engine stalling when the pressure gets too great.
The hose is an important part of the pressure washer that needs to be tough and up to the job. Most petrol pressure washers will be used for some pretty heavy duty work whether it is at home or at work. The hoses will get dragged around lots of different rough surfaces and need to get into some tight areas. It is important that the hoses are strong enough to last and will not rupture. They also need to be long enough to get around the areas that you are cleaning. Often the petrol pressure washers come with a friarly long hose and have the option to buy extensions and adaptors to make is as long as you need. The high end braided hoses should last for many years with no problems at all. The more pressure the washer can produce the stronger the hose and the hose attachments need to be, if they are not strong enough the hose will split or the attachments will get blown off.
Once the water has been pressurised and pushed down the hose it will go into the gun ready for the water to be sprayed. The gun has a trigger that when pulled will release that water at the required pressure. The gun need to be light and comfortable to use especially if you are working with your petrol pressure washer all day long. It also need to be very reactive so that it is easy and quick to turn the water on and off.
Finally the gun pushes that water through a nozzle before it hits the desired surface to start cleaning. The nozzles come in a variety of sizes and styles different widths of cleaning, different angle so of cleaning and turbo nozzles for very concentrated cleaning. Most models come with a standard set of nozzles to cover most of the cleaning needs but other can be purchased if they are needed.