Water has already been tried. Soap has already been used. Scrubbing and scouring have already been done. You’ve tried some nasty chemicals that did not work. When it won’t come clean, what can you do? Get the pressure washer out! Power washers, also known as super-powerful hoses, use pressurized water jets that are about 100–200 times the air pressure around us (in other words, 1500–3000 psi), to blast things clean. All sorts of outside grime can easily be removed with them, including those on patios, driveways, lawn furniture, barbecue grills, and more. Read on for more details.
The photo shows a small Kärcher Pressure Cleaning in Wollongong suitable for home use. In this one, a pressure of 1400psi (95 times atmospheric pressure) is achieved. It uses about 5 liters of water per minute, which is typical of electrically powered washers.
The polarity of water molecules accounts for this: one end is positively charged, the other negatively charged, so molecules tend to stick to things all by themselves. Detergents (soap chemicals) aid water in flushing away gunge and grease by breaking them down. However, some types of ground-on dirt simply will not budge.
When that happens, a pressure washer is extremely useful. The water jet is narrow, high-pressure, and blasts dirt from the surface. Since the water is moving fast, it strikes the dirty surface with high kinetic energy, knocking dirt and dust away like a constant stream of small hammer blows. It is only water, so most hard surfaces are not damaged by it. If you’re unsure whether a pressure washer will harm the surface you’re cleaning, test it on an inconspicuous area before use. Make sure you follow the instructions carefully.
Pressure water system components
It’s simpler than you think to use a pressure washer. All it requires is an electric motor to pump the water. Water is taken in through a faucet (that’s a tap to you people in the UK), the pump accelerates it to high pressure, and then it is sprayed out of a trigger gun at high speed. To clean different things with the hose, you can attach various attachments.
In a pressure washer, you’ll find the following parts:
Pressure washer’s water supply hose: A device that connects it to the main water supply. Dirt and debris are usually prevented from entering the washer by a filter in the inlet. There is nothing worse than having a washer full of little bits of grit – especially when they could come bursting out of the other end at a high speed!
Gas engine or electric motor: Most smaller pressure washers (such as those made by Kärcher) are powered by the home’s electricity, but bigger models use compact gasoline engines. They’re similar to lawnmower motors (typically rated at between 3.5 and 5.5 HP or 3–4kW). The gas engine models are ideal if you need to work outdoors in places without an electricity supply (or where running a long cable would be dangerous or inconvenient). The pump is powered by the engine.