When you are shopping for an pressure washer, you need to know the difference between PSI and GPM. PSI stands for pound per square inch and measure the pressure of the water that is hitting the surface you are cleaning. GPM stands for gallon per minute and measures the volume of water that comes out of the pressure washer.
High PSI indicate that the machine can produce high pressure. However, high pressure is insufficient for cleaning effective the area. If a pressure washer has high PSI but low GPM, then the machine will be able to move dirt with high force.
What PSI and GPM Mean and Why GPM Matters
However, the low GPM will prevent it from being able to move the dirty debris away from the areas that needs to be cleaned. The GPM will tell you how many water the machine will move and how fast it can complete the task of pressure washing. To determine how effective the machine will be, you can calculate the cleaning units.
You calculate the units by multiplying the PSI of the machine by the GPM of that same machine. The higher the number, the more effective the pressure washer will be in its task. If you have a machine with high PSI and GPM rating, that machine will be more effective in cleansing a greasy garage floor than a machine with high PSI but low GPM rating.
The GPM will determine how fast the machine can complete its task. A medium duty or heavy-duty gas pressure washer will provide a higher GPM than a light-duty electric model. This means the gas model will be able to rinse the surfaces it is cleaning at a faster rate.
Therefore, if you purchase a pressure washer with high GPM, you will receive a model with a higher rate of rinsing its surfaces. A higher rate of rinsing will allow the workers to clean up the job that they take on in less time. The nozzles that you use with your pressure washer will determine how your water are distributed.
If you use the narrow red nozzle, the water will be concentrated into a small point. This nozzle is helpful for cleaning specific areas with built-up dirt. However, the narrow red nozzle will not be effective at cleaning large area.
If you use the wide white nozzle, the water will spread out and be safer for use on windows or the paint on cars. The water will not be concentrated on one spot. A turbo nozzle will spin the narrow jet of water in a circular fashion.
This nozzle has the benefit of the narrow and the wide nozzle. Another thing that you need to consider is the GPM of your pressure washer in relation to the water supply you have. If your water supply cannot provide the GPM that is required by the pressure washer, the machine will experience cavitation.
Cavitation is the act of the machine attempting to pull water from the supply hose at a rate that the hose cannot provide. This will cause the machine’s pump to create air bubble within the machine. These air bubbles will destroy the seals and the piston within the machine.
Eventually, this can destroy the engine of the pressure washer. To avoid this problem, ensure that the supply hose has enough diameter to allow the amount of GPM that are required by the machine. Another factor to consider is how the GPM will impact the effectiveness of the accessories that come with the pressure washer.
The surface cleaner, which is a disc attachment that cleans driveways, require a specific amount of GPM to keep the spray bar on the disc spinning. If the water pressure is too low for that machine, the spray bar will stutter. This will leave stripe on the area that is being cleaned.
The foam cannon also require a specific amount of GPM. This gun mix the water and the pressure washer’s soap to produce thick foam. If the water pressure is too low, the foam cannon will not be able to produce thick foam but will produce only watery drip from the gun.
Finally, the GPM and the PSI of the machine that you purchase should match the type of task that you will be completing with your pressure washer. If you purchase a machine with high GPM ratings, it can be problematic to use on wooden deck. The high GPM will carve groove into the wood.
Therefore, you should of purchase a pressure washer with the lowest GPM that will allow you to complete the task that you create. By focusing on the GPM of the pressure washer rather than just the PSI of the moddern model, you can ensure that you are purchasing a machine that will best fit your specific need.
