Chemical injector and ratios

So I tested my chemical injector and pump today to check my house mix ratio. I went from a 4gpm pump to 5.5 gear drive on a gx390 using a 2.1 hi-draw 3-5gpm injector with 50/50 mix of 12.5%. After washing a few houses with the new pump I noticed the mix not working the way it used to…had to soap a second time a few times even on siding with light mildew and algae.

So this is what I came up with in my test:

200 feet of hose. 5.5gpm GP pump/gx390. 2.1 hi-draw 3-5gpm injector. One gallon jug marked at 1 cup intervals up to 16 cups. M5DS tip. I pulled the trigger for 30 seconds into a 5 gallon bucket with my injector line in the one gallon “soap” jug. After 30 seconds I had 3.3 gallons and pulled 3.5 cups of “soap”

3.5x2=7 cups of soap drawn in 1 minute
3.3 gallons in bucketx2=6.6gpm=105.6cups in 1 minute minus 7 cups of soap=98.6 cups

98.6 / 7 = 14 to 1 injector ratio…if I was using a 50/50 mix 12.5/2=6.25 / 14 = .45% hitting the wall which explains why it wasn’t working very well.

Would a 20% 5-8 injector work better for my set up? This pump is putting out 6.6gpm…I tested it twice…same results. If I drew straight 12.5 then .89% would hit the wall which would be better. Just looking for some thoughts here. I think I tested everything correctly.

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I might be wrong, and this probably doesn’t answer your question, but a 2.1 ds injector is too small if you are using a 5.5gpm. I have a 4gpm and need a 2.3.

That could make a difference

2.1 3-5 injector was perfect for my 4gpm pump. I never had a problem with a 50/50 mix. I think I’ll order a hi-draw 5-8gpm injector (which has a 2.3mm opening) and retest everything

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Do some reading on here about undersizing your injector. You will find all in the search bar.

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I just made the move from a 4gpm to a 5.5gpm and I was running a PressureTek 2.1 injector on my 4gpm machine which was perfect for the 4gpm machine. I called PressureTek before my 5.5 machine came in and asked about the injector and they said keep running the 2.1 with my 5.5. Now I will say I just got my new machine set up today and didn’t run a bucket test yet, but I have found everything else the PressureTek guys have told me to be spot on so I’m not expecting anything different here. But I’m also running straight 12.5 90% of the time. I may dilute occasionally if the house isn’t bad, but straight 12.5 DS’ed has worked well for me

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For what its worth, on my 4gpm belt with general pump:

Pressure tek 2-3 gpm injector = 7:1 ratio
Pressure tek 3-5 gpm injector = 9:1 ratio
Stock injector that came with = 16:1 ratio

Knowing this has come in handy many, many times.

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If youre using 50/50 water/ sh and are at about .5% just use straight sh and now your at 1%. Easy peasy. If you need to go stronger than that get an x jet.

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I bought a 5-8gpm injector just to see how it is but yes I agree about DS straight 12.5% to be at the 1%

Let us know the Results

Tested the 5-8 gpm injector today. It pulls the same as the 3-5gpm injector for my set up…13.85 to 1. So now I have some extra injectors lol. It’s all good. At least I know what I’m pulling. I can still dilute my mix some for the summer but will diluting straight 12.5 once fall comes.

I’ll have to test a 2-3gpm injector as well to see what it pulls.

I’m amazed how underrated this HP5535 is…it’s consistently pulling 6.6gpm with the M5DS tip which is 1 full gallon more than what it’s rated. I’m not arguing…it just threw my injector ratios off a bit. I also tested my Northstar 2.5gpm pressure washer with a little gx160 and that put out 3.25gpm. If you’re just doing residential, who really needs a gx690?

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Did you ever test any more injectors with the 5535 pump? I anticipate being finished with the trailer tomorrow. Already switched over the pump and mounted it, just gotta finish up with everything else

This is the truest ratio tool I’ve found for guys like me that get lost on trying to calculate ratio. If the mildew starts to disappear immediately you’re to strong, if it takes 5 minutes you’re to weak if it’s 2-3 minutes it’s just right :flushed:

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There’s a stainless GP injector out there that Squid uses with different proportioners that’s supposed to work really well. Both the 3-5gpm 2.1 injector and the 5-8gpm 2.3 injector pull the same for me about 14:1. Some will go down a size and use a 2-3gpm 1.8 injector and that supposedly helps them pull more mix with their 5.5gpm pump. I’m happy with how my injectors have been working so I’m not bothering to change what last been working.

What @Kps0410 said is the most simple way to find your right house wash mix… it’s its not working just add more SH

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@Kps0410 thats generally how it ends up going for me. The reason I was asking is @Barry1 mentioned he was going to test the 1.8 injector, just wanted to see how it went.
On another note, I kinda screwed myself… I didn’t order everything at the same time, so my 7.0 nozzles won’t be here in time for a few jobs I’ve got lined up, and I need to set the unloader. Not sure how I’ll proceed with that one…

Buy a red tip from the store. Any big box hardware store will sell them.