Different Pressure Washers

Discussion in 'Power Washing' started by GreenGiant94, Jan 29, 2011.

  1. gasracer

    gasracer LawnSite Bronze Member
    Posts: 1,049

    The 3.5-4 gpm is great. I wouldn't worry so much if it was 3000 or 4000 psi. Belt drive would be better but just get one with a good quality pump.Honda engine is a must.
  2. GreenGiant94

    GreenGiant94 LawnSite Senior Member
    Posts: 271

    Alright cool! Yeah the belt drives are just too much for me as far a money goes. Direct drives still are good though right, just not the best.
  3. GriffinLawnService

    GriffinLawnService LawnSite Member
    Posts: 235

    whats a good commericial grade pressure washer? What do yall suggest. I am looking to add this service to my lawn care program and I have no Idea on what brands to stay away from
  4. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    Ok, I know this is sort of a hijack, but I was wondering where one finds larger GPM tips for pressure washers? I have a 3500 psi machine but I think it's 2.5 gpm, maybe 3. Not positive. It has the quick connector style tips, are most of these universal? I would assume it would pump more volume, at a lower pressure, with a larger tip size. I just find that the wand at the car wash does more good than mine (vehicle and equipment washing) as they are higher volume and much less pressure. With mine I almost get as good of a cleaning job just using a jet nozzle on the garden hose.
  5. Pumptecguy

    Pumptecguy Inactive
    Posts: 71

    To all, here are some cleaning facts that should help you make a more informed choice:
    1) The nozzle creates the pressure, not the pump. The nozzle performance is based upon the amount of flow.
    2) The pump puts out a fixed amount of flow at a specific speed. Increase speed, increase flow; decrease speed, decrease flow.
    3) You need a ratio of flow to pressure to provide maximum cleaning power and effectiveness. Too much gpm to psi will waste water and have little cleaning impact. Too little gpm to psi and the water loses its' impact very quickly. The optimal ratio is 1 gpm per 300 to 400 psi.
    4) A larger nozzle will NOT increase flow unless the original nozzle was undersized. If the pump is operating at 3 gpm no nozzle will allow it to operate at 4 gpm.
    5) Direct drive pumps will wear out faster than belt drive. Speed kills. For example, the plunger can only go through the seals a certain amount of time before it is worn out. The belt drive pump may require 1200 rpm to deliver 4 gpm while a gas engine pump will do this flow at 3600 rpm - 3 times more. This fact applies to all the parts inside direct drive pumps. Direct drive pumps are disposable and made in Italy/China for this reason.

    I always recommend buying the PW that is best suited to your use versus one the is cheap or has big numbers. Cleaning concrete with a hard surface tool requires one type of performance (high psi) and cleaning wood requires another (lower psi with more flow). If you are cleaning your lawn equipment or other machinery, you cannot afford (the damage caused by) a 4 at 4000 washer, but would be better served with a 4 at 1500 washer - much cheaper.

    I hope this helps someone not make a mistake or waste money.
  6. JCinNJ

    JCinNJ LawnSite Member
    Posts: 159

    I have to disagree with a couple of your statements

    the pressure is created by changing the diameter of the tips.
    smaller dia. = more pressure
    larger dia. = less pressure

    You can wash anything under the sun with a 4gpm/4000psi rig just by changing the tips (and different cleaning solutions) to create more or less pressure. The smaller tips will damage concrete and the larger ones will allow you to wash your dog because the pressure is so low.

    All that being said, the more GPMs the better because it cuts your rinse time way down

    To get your tips, go to PT State
  7. Pumptecguy

    Pumptecguy Inactive
    Posts: 71

    There is no disagreement with what I said. Look at 1). In fact, you go on to agree with me with: you can wash anything under the sun with a 4gpm/4000psi rig just by changing the tips (and different cleaning solutions) to create more or less pressure. The smaller tips will damage concrete and the larger ones will allow you to wash your dog because the pressure is so low. You just stated the same fact from the other side of the equation. I assume a fixed nozzle size and you assume a fixed flow. The principle is the same. I'll take half full and you take half empty. :)
  8. Jason Rose

    Jason Rose LawnSite Fanatic
    Posts: 5,858

    So if I understand correctly, if I have a 3.0 GPM pump it doesnt matter what nozzle I use it's going to put out 3.0 GPM only, but the larger the nozzle, the less the pressure will be?

    To me that doesn't make a lot of sence... Larger nozzle= more flow (higher GPM) = lower pressure as the pump can't create more pressure than what it was already.

    So I could pull the nozzle off of my wand and, in theory, the flow out of the wand, with the pump running, should be the same as if I had a nozzle on it? I'd measure the flow rate with a nozzle, but it's a litte hard to catch 3,500 psi water in a bucket, lol.
  9. JCinNJ

    JCinNJ LawnSite Member
    Posts: 159

    The flow will always be 3gpm (or whatever the pump is rated for), the pressure changes when you change the dia. of the tips

    If you take the nozzle off your wand you will still be getting 3gpm but very little pressure, try that in your bucket.

    OK, think of it this way,

    1) go in your back yard and cut the male end off of your hose
    2) Turn on the water full blast
    3) now slowly pinch the end of the hose and pay attention to what happens to the water pressure.

    You are making the dia. of the hose smaller which is the same as adding a smaller dia. tip to your PWer
    Last edited: Mar 5, 2011
  10. Propowerwash

    Propowerwash LawnSite Senior Member
    Posts: 337

    The pump will run fine Direct, we have a multiway ball valve on all our equipment so we can run direct if needed.

    A standard 1/2 inch hose bib will flow at 7.3 GPM. So if your running anything under that you will not cause damage. Be sure hoses are not kinked, restriction in water flow will cause the pump to suck harder and if the flow is not right then causing heat. Heat is the ultimate enemy of the pump. The water we actually use cools the pump so it doesnt get hot.

    All plunger pumps require water to cool them. About three minutes with no water source depending on outside temp will cause damage to your pump.

    Another problem that when you leave the trigger off on a protable machine the by-pass just recirculates the same water through the pump. This water will eventually get hot and cause possible damage aswell. The tank people pull from is primarily used to by-pass water so pressure washer pumps are getting fresh cold water constant.

    This is not needed if you take care and make sure you always hook up to a connect not restricted, do not leave the washer run with gun closed to long.

    If you simple make sure of those two things you should not have any issues.

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