gpm vs psi

rando

rando

New member
i am looking to upgrade my pump this year to a 8gpm. the one i am looking at is rated at 2500 psi and due to the size of my engine (18hp kohler, thanks paul) that is about the max i can go on psi. will this amount of psi still do the job with surface cleaners? if so, what is the max dia that i can use? i do more residental than commercial and a ton of driveways so i did not want to lose that part of my business. i'm waiting on some good feedback before i purchase the pump.

thanks gang,

rando
 
Rando, I run 5.5 gpm on a 13hp Honda at 2500 psi and have no problems cleaning concrete with it. I believe theres a few other guys here and on PT State that do the same thing.
I use 15 deg. nozzles on the surface cleaner and that seems to help with the dirtier concrete.
It would be nice to have an extra 500-1000 psi at times, but its not worth the $1500+ for a bigger engine to do it IMO.
You wont lose any driveway cleaning business with that much psi. Youll clean concrete alot faster with 8gpm so in theory youll be making more.
I say go for it!!
 
kewl beans

thanks chad,

may i ask what size surface cleaner do you use? my largest one right now is a 20" and i was wondering how big i could go. size matters...right?

rando
 
I run a 20" s.c.'er. The rule of thumb is 4" per gpm. So in theory you can run a 32" at a pretty good speed. I dont know anyone with one that big though.
But Ive seen guys with 20" s.c.'ers on 8 gpm machines and can run with them on a driveway. LOL
Just keep in mind the smaller surface cleaners are easier to carry around/maneuver.
 
Johnson said:
Rando, I run 5.5 gpm on a 13hp Honda at 2500 psi and have no problems cleaning concrete with it. I believe theres a few other guys here and on PT State that do the same thing.
I use 15 deg. nozzles on the surface cleaner and that seems to help with the dirtier concrete.
It would be nice to have an extra 500-1000 psi at times, but its not worth the $1500+ for a bigger engine to do it IMO.
You wont lose any driveway cleaning business with that much psi. Youll clean concrete alot faster with 8gpm so in theory youll be making more.
I say go for it!!
Click to expand...

....+1
 
At 8 gpm+ anything over 2000 will clean about the same, in my experience. Try all tips and angles and bar tilt yourself and see first hand what works for you.
 
That psi should be fine the gpm will make a huge difference.

If you ever need the higher pressure and you are running a trap pressure unloader you can make adjustments to get 3500 psi when needed (as long ans the pump is rated that high). Set your unloader to 3500 psi then drop your tip size down to a #6 which will bring the operating psi up to 3500, the excess water from the pump will bypass and the engine will be able to meet the power requirements. (You will be running 3500 @ 5.6 gpm)
 
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