Howdy yall. I have a one off soft wash job to clean some dark stains in commercial limestone. It’s going to need a strong mix to kill.
I run a 8gpm honda grx800. I have an xjet and according to the chart, with an open proportioner it should draw 3:1 at 8gpm.
I reduced the rpm to 2100 to reduce flow to 5GPM. I tested it with a 5gal bucket. Its still drawing at about 3.5:1 even at reduced GPM. It takes 3minutes 30 seconds to empty the 5 gallon bucket at a 5gpm flow rate.
Any idea what’s going on here? Its a little higher than what the chart says it would draw at an 8gpm flow much less 5. It should empty the bucket in 2 minutes.
Wait until someone with more experience chimes in, but I don’t believe lowering the rpm’s makes as big a difference as you are hoping for, maybe try to restrict flow using a ball valve and bypassing some water?
I called X-Jet and they answered immediately. It was explained that lowering the rpm also lowers the pressure which alters the chemical draw.
However I did some testing after the call.
My machine at max rpm puts out 7.5gpm at (4000psi at the unloader) based on filling a 5 gallon bucket in 40 seconds.
At this setting I’m draining the 5 gallon bucket in 3.5 minutes, so the ratio is 5.25:1.
At 2100rpm its about 5gpm and also draining 5 gallons in 3.5 minutes. 3.5:1 ratio.
According to their chart at 8gpm I should he drawing 3:1. So I still don’t know what’s going on. I removed 100’ of hose. With 100’ hose remaining it remained the same.
I agree. This job however is an hour drive away and night only. Also its about 11,000 sf of wall surface area I’m cleaning so I don’t want to waste time and bleach. I want make sure I have enough bleach and can reach the areas I want to clean with sufficient strength so I’m not spending several extra hours and nights driving. Also getting this figured out now makes it so I’m prepared next time for a similar job. I’ve never really soft washed before so this will keep me set future opportunities.
First, you need to learn to do math. 2nd, what’s your flow rate at the end of your 200’ hose or whatever you’re going to be using, not at the unloader, with the xjet nozzle on it at each setting.ie how long to fill up bucket at respective settings
I thought I had my numbers right, care to elaborate? Flow at hose end is 7.5GPM. Didn’t test flow with x-jet attached, I assumed it would stay at 7.5gpm. I tested how long it took to empty a 5 gallon bucket with the xjet. Assuming 7.5gpm at hose end and 3.5 minutes to empty the bucket that would mean 26.25 gallons of water went through the pressure washer in the time it took to empty 5 gallons of chemical, (26.25/5)=5.25 gallons of water for each gallon of chemical. Drawing straight 12.5% bleach, it would be a 2.38% mix at the nozzle.
Test it with the xjet nozzle tomorrow and report back. But think about it. In total you shot 26 + 5 out of bucket in that time, so for your real % you probably need to divide by 31ish, But let’s see what you get on test. I’m thinking that nozzle may restrict flow some obviously. See how long it takes to fill up 5 gals. Then we’ll both know.
I’ve put a vacuum gauge on different size chemical injectors for testing.They all draw the same amount,what’s making your solution stronger is a smaller injector slows down the flow which raises your final ratio at the gun.Same thing with a x-jet.
