Power washer's psi & the pump

The next major factor in a pressure / power washer is psi "pounds per square inch", this all starts in the pump the heart of the power washer. Simply stated the psi is the force of the water when it exits the end of the nozzle. We talked about how a washer needs a certain size of nozzles to operate at it peak efficiency. If we use one too large the water flows out with less pressure to small cause to much pressure which could harm the pump head.  Any water flowing out of a hose, pipe or sink tap is a form of a power washer simple may it be. It has all the components of the power washer. Lets review first a pump is need to push the water to your home or pumped up into a water tower, where pressure from water being pushed puts it under pressure. Second the pipes keep getting smaller as the head for your home this put the water under even more pressure. Then when it reaches your house then the nozzle at the sink, shower or garden hose puts it under more pressure you have increased the psi to about 30 to 40 psi as it flows out when you turn on the faucet. From still standing water being pumped along in the pipes and nozzling restricting its flow you have the basic power washer, you can now use it for cleaning in the shower the sink washing off you side walk. Now lets take it to the next step more psi an added pump what can we do now.

We used a pump to get the water up in the water tower and then gravity and reducing size of the lines cause the pressure and the shower head, your thumb or garden hose nozzle adds the finial major component and we have all the parts of a simple power washer not to powerful but by definition a power washer, pump, pressure psi, water gpm and a nozzle.

The power washer has several styles of pumps that increase the pressure of the water but it always comes down to: compressing the water into a hose regulated with a nozzle. That stored water power holding in the hose under pressure is the psi rating. We can buy different types of washers with psi ratings from 80 psi to 10,000 psi. Residential units and commercial units are available to buy, though commercial units are built with better parts and will always out last the ones you may buy at the "big box" store. I bought what I considered the best unit I could find when starting in the "water pressure washing" business, it was 3500 psi and put out 4.5 gpm and could heat water up to 210 degrees also ran a 110 volt generator with a 2 cylinder 18hp gas engine. This unit set us back around $10,000.00  and with up keep and new parts when needed we still us the same unit today. Cleaned by Pete has the crazy idea buy the best this in-turn help us to to the best for our each or our customers. We don't believe by a entry line equipment and make more money then disappear and find something else to do when it breaks down. We are in the power washing business and this is all we do "mobile contract cleaning" or "water pressure cleaning".

Our unit is a Landa washer bit older but has the same power and components as this one.

You'll see that our unit is a bit better than the $400.00 "box store" unit but now we need to get back to psi and pressure. Some form of motor has to run the pump the major types are electric powered using 110 volt to 220 volt single phase all the way to 440 volt three phase. My first introduction to a power washer was in my high-school years where a local restaurant chain used hot water from their boilers to supply water to a small wall mounted electric pump unit. I used to wash the floor in the kitchen each night it made for a fast and easy way to clean each and every night. While it did not put out a lot of pressure with the correct nozzle and the hot water it was easy control the pressure stream and get things clean in much less time. This is an example of saving electricity, water, work time and energy to heat the water thus making the pressure washer an environmentally friendly machine as we talked about in earlier posts. The second form of power is "gas" motors (these motors run on gasoline, propane or diesel fuel but we will refer to them all as gas) from the smallest I have see is 2.5 horse power to 8 cylinder car type motors to run pumps. What you need to use depends on the pump and what you are doing. The psi out put of a washer can help or hinder. In the wrong hands you can actually blow the siding off a house, gouge out wood and etch concrete as shown before. Below are examples form a small electric to a huge industrial for cleaning oil rigs. In the right professional hands a tool for good in the wrong hands can cause real harm to your home and possessions.

A small electric unit around 800 psi to 1200 psi out put at 2 gpm

A large 10,000 psi unit at 22 gpm

Some consider the pressure washer pump to be one of the most significant advances in modern tools or engineering today so simple but able to do so much. To make this easy I will list a few styles and then have a short discussion on each pump from the most popular down. I'll miss a few. I'll just hope to arm you with enough information to help you defend yourself from those who want to make a quick buck and leave you with what shows up latter. Pressure washer pump come in these styles plunger, rotary, and diaphragm pumps these are the most popular ones found in use in the power washing field there are others but not that common.

The Plunger pump is found in different forms and configuration. Water pressure is formed by a plunger or piston compressing the water with one valve holding it till is is compressed and another valve opens and lets the water enter the water exit line or hose which builds up the psi to the pumps setting. These pumps usually are found in a 3 piston configuration called a triplex pump or with 2 pistons or plungers. Now the pistons move in and compress the water in the pump head, in 2 different style one us use mainly for residential use called the wobble pump. For commercial and "upper-end" residential the pistons (plungers) move on a crank shaft  pushes in the piston and then pulls it back out just like the pistons in your car. The wobble pump has a special plate which has a high spot. As the plate turns the high spot in the plate pushes the pistons in and a spring pushes it out in the head using the same style of valving the pressure is captured and then released in the the line hose. This holds true for triplex "3 piston" or the 2 pistons models. As the spring or the crank pulls out the piston water rushes in from your house or a tank and the cycle of compression is started again over and over. You will see more of this style pump on the pressure washers you can by. Most self-service car washes use this type of pump it is very durable and totally rebuildable and are built in various sizes to fit most applications. This pump is also designed to run on various types of motors vertical and horizontal models, belt drive, gear reduction, or direct drive are available. There are also difference in construction and materials used which determine how long and what service you can expect form a power washer.

Triplex Crank Style Piston Pump

I'll end here today and take up again on the pump creating the psi in the next instalment of the blog. I'll try to explain about the other different style pumps.  Components why are some better than other, and why Cleaned by Pete has several different washers and style of pumps. Hopefully you will see that most professional water pressure cleaning companies use commercial and high standard grade equipment if you don't see this it may be a tell tale sign to you as a customer.