Metered Injector vs 20% injector

Hi Guys

I’m having some troubles understanding the injector with metering and a 20% downstream injector, Maybe you could get me some of your knowledge?

I tried an injector that pulled 5 cups in a minute and the ratio is somehow strange so I was looking around and found the “Best injector” video but to be honest I quite didn’t get it.

If I use that injector and and dial it down to 1% via the colored screws, does it mean I get 1% of the solution at the end of my nozzle? Or how does that work? I’m a bit too confused by that.

I am kind of scratching my head. What is a 20% injector? That would be really strong for a DS injector. “Best Injector”? Got a link? I would guess you may be thinking of a porportioner/mixing system?

My understanding is for pretty much all injectors you have to test them to see what they’ll actually pull with all of your specific equipment.

With 20% I mean the high draw injector which stated to pull up to 20%.

And here is the link to the metered injector.

I checked my DS and it pulled 5 cups in a minute with my 4gpm/4400psi machine which leaves me with a strange ratio. I just try to understand the metering injector etc to get the most accurate % at the end of the nozzle.

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I’ve always heard they pull 10:1 and you’re getting 12.8:1. You’re never going to get exactly what they’re labeled for because of the different variables. There’s no need to be 100% accurate. Just round up or down for easier math and call it good.


If you’re pulling a 12.8/1 ratio and you’re using 12.5% SH the math is easy if you want 1% hitting the wall…just put your surfactant in straight bleach and roll.

I haven’t tried the metered injectors…I just stick with my 20% high draw 2.1mm GP injector…
I’ve had this one for about 1 year after well over 100 jobs and it’s still pulling with 200 ft of hose. I always flush my injector with fresh water at end of each job so SH doesn’t sit in there too long.


Makes sense. Like Marine said you don’t have to be super precise.

That sounds great but I think I have difficulties understanding the statement from other guys when they say they use 50/50 mix and running a 8gpm machine. This would even raise the ratio to 25.6/1 and effectively leading to a 0.488% mix at the nozzle which might be too low.

Could someone shed some more light into the metering valves and how they work or how to calculate whats coming out at the nozzle?

I think many like a .5 to .8% mix hitting the surface and are willing to go back over areas not cleaned. Others want 1.0 to 2.0% hitting the surface so they don’t have to go over uncleaned areas. Personally I aim for the middle right near 1.0 plus or minus a little.


The “mix” is usually half water and half 12.5% SH that people refer to as 50/50. That is what their supply line to their ds injector is in. So, that is typically strong enough to clean most houses. Even a 60/40 mix will clean most. The “best ever” injector limits the “draw” of the mix to basically get that magical 1% or so on the house. A few reasons those “best evers” gained traction are no more batch mixing your ds mix, saves time and ability to haul SH. Instead of a ds tank and straight bleach tank you only need one. Maybe this helps. Also, everything will have an affect on your percentage that hits the house. Such as hose length, debris in your mix, bleach loosing strength due to age/exposure, % of SH and pump performance on and on. Just understand it’s not rocket science.


Everyone’s set up will pull a little bit different ratios. Some people’s 4/4 will pull 7:1 where others pull 12:1. I run a 5.6gpm pump with a 2.1 3-5gpm injector wth 200ft of house and pull 13.8:1 so I just downstream straight 12.5 and it works great for me. I believe Racer on here pulls 18:1 with his 8gpm DS set up which puts him at .7% which works great too. I would focus on your set up and play around with it. At the end of the day…if the hw mix isn’t working…add more bleach until it does.


Alright, I’ll get a fixed DS injector now and see whats coming up. I’m cleaning concrete so I probably pull it straight which comes to 1% for pre-treatment. Thank you guys!

Not my setup but how do y’all feel about this?

It cuts out the duel barb injector and instead uses valves instead. Chemical resistance is better long term but, I think this would cut your strength like crazy

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Im been trying to figure out something similar. I have a shertz box so I dont believe it’s possible to use a dual barb Injector one for soap one for bleach but could run some sort of valve system like that on the pick up end. I’m sure it does restrict some flow so keeping all plumbing to a minimum would be needed.

You would just cut the draw line and add a T on the schertz box… but idk about the strength you would get

I may end up testing something like that this this winter so I’d let you know unless youd like to do it first :joy: I have a feeling youd have to find a suitable replacement for the 1/2" metering valve and go smaller maybe not but it seems like a lot of space for a little bit of liquid to fill

Lot of unnecessary stuff going on there. Injector, three way valve(remote or otherwise), tank full of 12.5, dump in your surfactant, wash.


But they want the disappearing pink soap lol it’s a must have !