Soap Warehouse Blog

Some have said my post a few years back about how to calculate the dilution ratio of a pressure washer to use to figure soap use was too complected and I had directed people to an online calculator to do the math. Well I will attempt again to explain how to do all the math you would need to do to figure out how much soap to use for a job. At least to start with. Other factors may require tweaks from the calculated numbers.

So let's first start with your machine. Say it is a 5 GPM unit. We first need to check to be sure that is accurate. (You should continue to do this every few months to be sure it is staying where it should be.)

To check flow rate for 1 minute to see how many GPM your washer is currently putting out. Use a container that can measure gallons on the side and fill it for a straight 1 minute full open. This should be done with the tip you will be using on the end of your wand. Let us say you have a perfect machine and you get a full 5 gallons in that one minute.

Now take a gallon container that can measure by ounces on the side and fill it with water and drop in your downstream line (normally this would go straight into your concentrated soap or soap mix)

Turn on and draw the water from the container for 1 minute. This will show you have many ounces per minute you are drawing. Let us say you got 40 ounces.

Now we take those amounts that you got and run the numbers.

5 GPM is 128 (ounces in a gallon) x 5 = 640 in one minute.

Draw rate from your minute test (it was 40)

640/40 = 16. 15 parts water to 1 part chemical so you have a 1:15 ratio.

Next the soap you want to wash with has a starting recommended ratio to use of 1:35 with cold water so you need to know how much water are you going to add per gallon of your soap to make your mix for your machine to deliver the 1:35 ratio out the wand.

You need to find X;   1/15 = X/35.  So divide 15 into 35 and you get 2.3.

cross multiplication 1x35=35/15=2.3

So you will add 1.3 gallons of water to the 1 gallon of soap concentrate so you end up with a total volume of 2.3 gallons this is what you will drop your hose into to draw the soap to get the 1:35 ratio.

So what if your soap reservoir can only hold one gallon?

More math! You turn the gallons into ounces 2.3 gallons is 294.4 ounces.

294.4/128 = 128 (the single gallon of your reservoir)/X

Cross multiplication again. 128x128= 16384/294.4=55.65 ounces.

That is how much concentrated soap you will put into the gallon reservoir topped off with water to still give you the 1:35 ratio out the wand.

So you start to wash and it is cold outside, the surface is dirtier than you thought, etc. and the soap is just not cutting it. I always suggest going up in 10% increments at a time until the soap is working. So for this mix I would add another 5-6 ounces of soap to the reservoir once their is room.

Or if the opposite is happening and you find that the soap is cleaning gang busters then increase the amount of added water by 10% at a time until it is not as effective. So for this gallon reservoir that would mean to add 13 ounces of water, when the level got low enough, and see how that was cleaning.

Once your soap has reached it's effectiveness, using a higher concentration of it is just wasting soap, not increasing the effectiveness of your cleaning so try to not waste soap.

And remember using warmer water will reduce the amount of soap you will need, since the heat increases the efficiency of the soap up to half as much.

If you have any questions about ratio calculations just give me a call. 800-762-7911.

I must try and help out customers with this almost everyday so I thought I would make a post out of it and possibly a white paper to send out so I would not have to repeat my self as much and for easier reference.

Plus I can easy get confused or tongue tied so it is a good idea to have it all written down some place.

First you will need to know how you are going to apply the chemical mix. Figuring ratios for a pump up sprayer is easy, but the most common piece of equipment for this need is the pressure washer. So you first must know what dilution ratio or fixed mixing ratio your machine puts out. This can be easy for some, but many customers call me all the time saying they have no idea how much chemical their machine takes in and how diluted it is sprayed out.

The first place to look is in your machines owner’s manual. It should give you info like its flow rate or the gallons per minute the machine can generate plus its fixed mixing ratio. This can vary by machine and some larger models may even have a dial that allows the operator to change the mixing ratio. Another place to look if you no longer have your manual or if you bought your equipment second hand and never had one is on the internet by putting you make and model number into the search engine. You can also sometimes go to a local dealer that may have manuals in stock or that can order one for you.

A harder way to figure it out is to use a do it your self method. Take a measured 1 gallon (128 fluid ounces) and place it in your machines chemical mix tank or insert your down stream hose into the gallon container. Turn you machine on and run it dispensing all the water coming out of the wand into a much larger container, such as a 5 gallon bucket. Take care to have the machine set at a low PSI so all the water makes it into the container, a closed 5 gallon tight drum is good for this. Once you have drained the gallon of water out of your chemical mixing tank or with your down stream hose measure the amount of water you ended up with and then divide the amount by 128 (ounces in one gallon) to find out your machines ratio. If you ended up with say 900 ounces you would get the results of 7.03125 which I would consider being a 1:7 ratio. I would run this experiment at least 2-3 times comparing the results and taking the average for best results. Some of our customers have even been known to add food coloring to the original gallon to help them gauge when they have used all of it up.

So lets us say your machine has a permanent setting of 1:7 and you need to take your concentrated chemical and get it up to a 1:25 application ratio. So you need to figure out how much water to add to your chemical, that once it is placed in the chemical mixing tank or suction hose dropped in the container you are down streaming from, your machine will produce the needed 1:25 ratio.

This means we have to use the algebra we never thought we would ever need once we learned it and then for got back in school and create a mathematical equation to do our work for us.

First we will put the dilution we need to end up with on the left side of the equation (see below)

Next we have the detergent, ‘d’ and water to think about. Say we want to make a 5 gallon container, ‘p’ of chemical product mix. And (p-d) is the amount of water we need in the container and 7p is the additional amount of water that the machine will be adding while dispensing the contents of the container. So we set p=5 gallons and we solve for d and find that d=1.538 gallons of detergent.

1  = ____d_____

25     (p – d) + 7p

Now I am not going to sit here and teach you how to step by step figure an algebra equation that many would not be able to remember just like back in high school. But I am going to give you the link to a web site that has a dilution calculator right there for you.

http://jansson.us/mixingratio-concentration.html#pressureWasherCalculator

What I suggest is that you go to this site, bookmark it, make the calculations for all the products you regularly use knowing your own machines ratio and our products dilution rates or the ones you use with our products. I would then round the results and make a dilution chart to keep as a mixing guide.

Here are just some examples from what a few customers I know have and the products they use as some examples.

Customer #1 uses Brown Derby with cold water that we suggest mixing at 1:50. His machine is set from the factory at a 1:20 ratio and he mixes his premix in 5 gallon pails that sit on his truck.

His equation would look like this

1 = ______d_______

50     (5 – d) + 20*5

But in the calculator it looks like this

 Detergent Water Final Mixing Ratio: : Pressure Washer Mixing Ratio: :

Desired Volume of Pre-mix:  gal

 Pre-mix Concentration: % Detergent: gal†= fl. oz Water: gal= fl. oz

Giving this customer the directions to take 2 gallons (rounded down) of our Brown Derby with 3 gallons (rounded up) of  water to make his pre mixed 5 gallon pails to down stream with his machine to get a very close 1:50 ratio of cleaner to water.

Next let’s take one more case:

Customer #2 uses Mighty Max as a house wash at a 1:20 ratio and his machine is set at a 1:7 ratio. He on the other hand only wants his 5 gallon pails filled with 3 gallons of mix so they are easier to carry to move around the houses. His results would be this:

 Detergent Water Final Mixing Ratio: : Pressure Washer Mixing Ratio: :

Desired Volume of Pre-mix:  gal

 Pre-mix Concentration: % Detergent: gal†= fl. oz Water: gal=

Or if rounded, 1 ¼ gallon of Mighty Max to 1 ¾ gallons of water, making a slightly greater than 1:20 mixture.

Once you know your normal values you can adjust the mixtures as needed for other considerations like water temperature, air temperature, or amount of product you have left available to do a job. How to estimate soap use for your whole season will be kept for a later post. Use this winter time off now to make these charts and you will be better prepared for spring.