randyh56

[randyh56 14]

I could use some help and examples on the mix ratios for chemicals. I bought a downstream chemical injector for outside the pump. It is 2-3 gpm adjustable. The pump on the machine is a 1-7 ratio. The machine is 2.6 gpm at 2750 psi. I'm not sure how to figure say on a 1 to 10 mix on my cleaning solution. I would set the injector at 2 gpm. Proably should have bought the non-adjustable. I would appreciate some help on this.

[RyanH 14]

A little confused on the post I am, yes.

Is the downstream injector an actual pump that pumps chemicals into your pressurized water stream, or is basically a nozzle to which you hook a hose that is fed by the chemical tank? I'm guessing your pump/pressure washer is a 2.6 gpm and can put that out at 2750psi. Your downstreamer will pull chemicals in at a ratio of approximately 1 part whatever is coming in from your chemicals to 7 parts water coming out of your pump (basically, if you have a 2.6 gpm machine, after 1 minute you will have expelled 2.6 gallons of water and 0.37 gallons of whatever is in your chemical tank). If you are going to want to have the final concentation of chemical to be in a 1:10 ratio, you will need to dilute it a little before downstreaming it. Without dilution, using straight chemical will give a final ratio of 1:7.

If you want to make something 1:10, then for every gallon of chemical you have, add approximately one half gallon of water to it (0.43 gallons is more precise). This will give you a final ratio of 1:10 assuming your draw rates are accurate. Keep in mind that pulling a 6% bleach (standard store bought) solution straight from your Clorox jug into your machine through the injector will yield less than a 1% final solution and you will never get higher than this. Should you want higher you will either need a different injector or something like the Xjet, or a stronger initial concentration....just some points to ponder.

Also, changing the flow rate between 2 and 3 gpm on your pump will change the velocity which the water moves through your hoses and past your injector port, which will change the pressure at the port opening and will affect your draw rate ratio (giving you less draw), so reducing the amount of water flow will not automatically give you a higher chemical concentration out of your hose. You can overcome this by physically pumping your chemical into your injector with something like a ShurFlo, or keeping the chemical source higher than the injector port (like on a shelf above it).

[randyh56 14]

The chemical QC's to the outside of the pump where the pressure hose then plugs into it. It's an adjustable of 2-3 gpm injector. Now how does the water out of the machine at 2.6 affect the solution. I will set it at 2 gpm on the injector. What is the mix in the cotainer I am drawing from at. So as to achieve the correct ratio. Thanks for your responses

[RyanH 14]

Your ratio will be dependent upon what your injector is set to. For example, if you were to put your injector at full force at 3 gpm, then you will effectively be putting out more chemical than water at a ratio of 3:2.6. To figure in percentage, add both values together (chemical flow + water flow), then divide the chemical flow by the total flow to get the percentage of chemical by volume. In this example, it would be

3/5.6 = 54% chemical in what ultimately comes out of the end of your hose. What that means is that 54% of what is coming out of your hose is whatever was in your solution bucket. If you had 10% bleach in your bucket, then your final solution will be 10% of 54%, or 5.4% bleach, a little strong for a house wash mix. So, I guess this is where your question comes in earlier of how to premix your solution to get the final solution. If you need a final ratio of 1 part chemical to 10 parts water as is called for by some stock solutions, then you will need to either dilute the initial concentration or reduce the flow of your injector pump, or both. These adjustments are up to you and you can do whatever is easiest. Most people would prefer to adjust their flow rates, but in some cases you will have to also dilute down.

In your case, the lowest ratio you could ever hope for is 2:2.6, or 1:1.3. If you need a 1:10, you are going to have to dilute your initial concentration. You can use a little algebraic manipulation and see that you will need to put 1 quantity of your chemical and 7.7 quantities of water into a solution tank, then draw from this with your injector. To figure the numbers out on your own, you can use the equation:

W/I = 1/(RF) where

W = the amount of diluting water you will need to add to a solution tank in gallons

I = your injector flow rate (between 2 and 3 gpm in your case)

R = the ratio you need as a fraction of chemical to water (1/10 in your example)

F = the flowrate of your pressure washer pump (2.6 gpm in your case)

make sure your numbers are in gallons to make things work out ok.

This is not applicable when you are talking about concentrations by weight, only by volume.

[randyh56 14]

Thanks for the help I greatly appreciate it.

Randy