# Surface cleaners & engine/pump combinations

Discussion in 'Power Washing' started by Cleaning Greensboro NC, Aug 5, 2010.

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1. ### Cleaning Greensboro NCLawnSite Memberfrom Greensboro NCPosts: 31

SURFACE CLEANER GUIDELINES

Use two bar surface cleaners. Three or four bars spreads your power too thin.

I recommend using 15 degree nozzles for the 20-24" surface cleaners and up to 10gpm.

28-36" surface cleaners with 10+gpms use the 25 degree nozzles.

Use the barens nozzle calculator to figure out the correct size nozzles to use for your machine. Divide gpms by two for two bar surface cleaners.

20" surface cleaner: 13-26hp 4-8gpm @ 4000-3000psi

24" surface cleaner: 18-33hp 5.5-10gpm @ 4000-3000psi

28" surface cleaner: 24-40hp 8-13gpm @ 4000-3000psi

36" surface cleaner: 33-53hp 12-17gpm @ 3500-3000psi

http://www.barens.com/cgi-bin/calc

I used this chart and also measured the area of a circle.
From my experience this HP-GPM range for each setup (slow-fast) is pretty accurate.
You will be able to move each one about the same speed for it's range.

Area of circle = pi X radius squared.

20" = 314.159 inches squared
24" = 452.389 inches squared
28" = 615.752 inches squared
36" = 1017.875 inches squared

Your HP & GPM should be directly proportional to the surface area your machine will cover.

28" circle is 2.00 times larger than 20" so you need 2.00 times the HP & GPMs.
36" circle is 3.25 times larger than 20" so you need 3.25 times the HP & GPMs.
36" circle is 2.25 times larger than 24" so you need 2.25 times the HP & GPMs.
36" circle is 1.65 times larger than 28" so you need 1.65 times the HP & GPMs.

If you have more than one machine join them together to make more HP & GPMs.

You'll need a high pressure T and a short whip line.
Both your unloaders must be pressure actuated, and both pumps need to have the same pressure so they will be balanced and run at the same rpms.

If your surface cleaner comes with a 1/4" hose from the gun to the swivel, take it off and replace it with a 3/8" hose. Also the guns on the surface cleaner will eventually wear out and break, and they also restrict your flow slightly. To avoid any problems, take it off and use a quick coupler attached 3/8" heavy duty zinc plated steel 3000psi ball valve.

Example- 18hp 5.6gpm @ 3500psi + 13hp 4gpm @ 3500psi = 31hp 9.6gpm @ 3500psi

20hp 8gpm @ 2800psi + 13hp 5.5gpm @ 2500psi XX DOES NOT WORK! XX

I tried this combination and it caused my smaller machine to cut off and stall from the pressure difference.

If I ran the 5.5gpm pump with a 15-16hp engine this combination would work.

20hp 8gpm @2800psi + 13hp 5gpm @2800psi = 33hp 13gpm @2800psi WORKS!
20hp 8gpm @2800psi + 11hp 4gpm @3000psi = 31hp 12gpm @2900psi WORKS!

VIDEO DEMONSTRATION of 13gpm @ 2800psi on a Maxima 36" concrete cleaner

Using large intakes are especially helpful when running large volume 8+gpm machines.

Use a 2" single union ball valve attached to your bulkhead, attach to a 1-1/2" filter, attach to 1" hoses to your machines. Keep your 1" hose short as possible for maximum flow intake.

2. ### FCPWLLCLawnSite Senior Memberfrom Lexington, KYPosts: 352

Great info.... Glad you found your way over here.

3. ### Cleaning Greensboro NCLawnSite Memberfrom Greensboro NCPosts: 31

Thanks Mike. Like you said, only a few hours later and I'm on the front page!

Amazing traffic on here.

4. ### Cleaning Greensboro NCLawnSite Memberfrom Greensboro NCPosts: 31

One correction on literature above.

Change 3/8" heavy duty zinc plated steel 3000psi ball valve to:

3/8" heavy duty nickel plated brass 3000psi ball valve.

I know this is rated below some pressure washers, but it will still last, and the ease of use compared to the nightmare super stiff as f@ck higher pressure valves makes it a much more desirable ball valve to use.

5. ### Certified MD Roof CleanerLawnSite Memberfrom MarylandPosts: 41

Great post Mike. This is very useful info.

6. ### Cleaning Greensboro NCLawnSite Memberfrom Greensboro NCPosts: 31

Thanks Chris, good to meet you in Tampa.

Hopefully one day I'll have a rig as awesome as yours! LOL!

7. ### Certified MD Roof CleanerLawnSite Memberfrom MarylandPosts: 41

It was good to meet you as well. Finally got to put a face with the name.
Thanks for the compliment on the rig. Like everything else, it's never done. I'm getting ready to strip it completely down, sandblast and repaint the bed, and then put it back together, adding a 2nd hot water skid.

BTW I'm sorry I missed your call when we were in Tampa. I didn't get the message until I got back to the office on Monday.

8. ### ScottwashLawnSite Memberfrom Palm Coast FloridaPosts: 24

20hp 8gpm @ 2800psi + 13hp 5.5gpm @ 2500psi XX DOES NOT WORK! XX

I tried this combination and it caused my smaller machine to cut off and stall from the pressure difference

ok My machines are not this big but there are diffent hp I am using 5,500 psi check vavles. so the water can not back flow

Are you using check vavles?

9. ### Cleaning Greensboro NCLawnSite Memberfrom Greensboro NCPosts: 31

No, check valves are unnecessary.

You can also join two machines together using only one unloader. Run two short whip lines into a high pressure T into your unloader block, into your unloader. I used the AL607's black spring unloaders.

The YU-2140 green spring unloader is probably the best from what I have heard.

10. ### ScottwashLawnSite Memberfrom Palm Coast FloridaPosts: 24

The reason I have check valves is that when I start up the first machine or shut one off. I dont get high pressure going back to the unloader or into the pump on the pw that is off. Which is not a good thing. This set up came from Russ and I have not had any problem.