So, the most critical cleaning rating for pressure washers is called the CPU (cleaning power units). In order to find this CPU rating of a pressure washer, you multiply the PSI (pounds per square inch) by the GPM (gallons per minute). Therefore, the greater the CPU the greater the machine can clean deep and effectively. However, consumers are so focused on the PSI of a machine that they do not even look at the CPU. In many cases its not even mentioned on the advertising of a machine.
It’s all about the CPU
Therefore, If a power washer has 2500 PSI and 2 GPM flow rate it will have a CPU of 5000. Another power washer has only 2000 PSI but has 4 GPM. This will give it a CPU of 8000. The lower PSI machine has far greater cleaning power than the higher PSI rated machine. This means that the 2000 PSI machine will be able to clean the same area much faster than the 2500 PSI machine.
In fact, let’s compare a garden hose at about 6 GPM and 10 PSI giving it 60 CPU. If a spray nozzle is attached you can get about 5 GPM at about 40 PSI generating 200 CPU. Try to clean your patio with a garden hose and spray nozzle giving 200CPU…! Great for moving leaves!
You cannot in any way compare the cleaning power of an electric pressure washer from a Hardware store to a petrol driven machine.
Our petrol driven power washer is rated at 5.5GPM and 3000PSI. That gives a huge 16,500 CPU ! Being adjustable in its power it can be turned way down to trickle to suit the particular surface that needs cleaning. A big brand name washer just can’t compete with an industrial unit in any way. With this sort of power to hand we use some attachments that facilitate in a much quicker, and deeper, clean.
It is recommended that a deep clean is initially done by a commercial machine. Subsequently, it will be a lot easier to maintain with a normal electronic jet washer for years to come.