In dealing with dilution ratios in last month’s column on injection sprayers, when I explained that you should mix 1 part pre-spray with 16 parts water, I thought I’d done a good job covering the topic in full.

It became clear that a more detailed explanation was in order when I was later asked, “How much is a part?” Many folks seem to have an in-born aversion to math. As simple and straightforward as a problem might be, we just freeze up when numbers are involved.

Many of the calls coming in to our customer service lines involve calculating the proper amount of a traffic lane cleaner; deodorizer; protectant or other product to add to an in-line sprayer to achieve the proper dilution ratio. So let’s see if we can calm some of the math fears with a little explanation.

If you can answer one key question, you can usually determine how much of your concentrated product to start with. That question is, “How much ready-to-use solution will be sprayed out by the time the chemical jug is empty?”

Many in-line or injection sprayers dilute the cleaning agent in the jug with 8 parts water. We’ll begin with this standard dilution. Let’s also assume that the container will hold 5 quarts, a common size in the industry.

The 8:1 dilution rate means that the sprayer’s mixing valve will automatically add 8 times as much water as there is product in the jug before it is sprayed. For example:

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5 quarts of product from the jug + 40 quarts of water (8 x 5 quarts) = 45 quarts

45 quarts is a little over 11 gallons. This is how much ready-to-use solution will be sprayed out by the time the jug is empty!

If your sprayer has a 7-quart container, the calculation works the same way:

7 quarts of product from the jug + 56 quarts of water (8 x 7 quarts) = 63 quarts, or a little less than 16 gallons

Keep this equation in mind. The same sprayer set-up with the same jug will always have the same answer. You will never need to recalculate.

Now, if the label directions for a product read, “Use 2 ounces per gallon,” simply multiply the stated amount by the number of gallons of pre-spray your set-up produces. For 11 gallons, multiply 11 by 2 ounces and you get 22 ounces. Put 22 ounces in the chemical container, fill the rest with water and you are ready to go.

If the label calls for 8 ounces per gallon, multiply 11 by 8 and you get 88 ounces.

Add the correct amount of chemical to the container and fill it the rest of the way up with water. The amount of concentrate needed for any particular product can always be found by simply multiplying the number of gallons of product sprayed by the number of ounces needed for each gallon.

Suppose you have a small job. You don’t need to mix up a full container of pre-spray. Assuming the 8:1 dilution ratio, if you fill your 5-quart container halfway, you’ll only spray out half as much, or 5½ gallons total, before the container is empty. The math is easy: multiply the number of ounces per gallon by 5½ (5.5) instead of 11, and you come up with the correct amount of concentrate to create 5½ gallons of pre-spray.

Avoid the Math

A great leap for injection sprayers was the development of adjustable metering valves. This allows math-leery technicians to simply dial up the desired dilution rates. If you want 8:1, simply set the dial at 8. If you want 16:1, set the dial at 16. Adjustments can be made from 4:1 to 64:1 or anywhere in between.

This quick adjustment can be particularly useful when you run into a heavy traffic lane running down the hall or in front of a couch. You could move from a 1:8 dilution up to a 1:12 just for that area, then return to your regular dilution.

This is a much better option then soaking the area with twice the amount of regularly diluted pre-spray, causing over-wetting problems.

While not quite as easy as dialing up the desired concentration, the original style of injection sprayers include a metering tip inside the chemical draw tube that adjusts the amount of chemical drawn from the jug and added to the water supply. Changing dilutions is as easy as exchanging one tip for another. A set of metering tips that allows a wide variety of product concentrations costs only a few dollars.

Thick Chemicals

The stated dilution rates for injection sprayers are based on the product being sprayed having a similar viscosity or thickness to water. It is advisable to pre-dilute or “thin out” thicker products before pouring them into the jug on your in-line sprayer.

How might you achieve this? Simply focus on the amount of concentrated product you are using, not the diluted volume.

For example, a pre-spray that calls for a dilution of 4 ounces per gallon. Staying with our original example of a sprayer set-up that produces 11 gallons of ready-to-use solution, we know there should be 44 ounces (4 ounces x 11 gallons) of this pre-spray in our jug.

Now, to “thin out” the pre-spray, we may choose to dilute it with another 44 ounces of water. By doing so, even though our total is now 88 ounces, there are still only 44 ounces of pre-spray in this mix. Pour this into the jug and fill with water.

If you are using a sprayer that allows you to dial in the dilution, fill the jug with half pre-spray and half water. The product directions called for 4 ounces of pre-spray per gallon, but the contents of our jug are only half pre-spray and half water. Now what?

To reach the same concentration, we need to draw twice as much from the chemical container. So instead of dialing up 4 ounces per gallon (denoted as 32:1), dial up 8 ounces per gallon, which is 16:1.

How Much Do Your Chemicals Cost?

I’ve gotten you to think about the oft-avoided topic of math, so let’s cover a few more ideas. Maybe this will save some you some money and time.

You spot two products on the shelf at your local distributor. Product A sells for $19.95 per gallon, while product B retails for $29.95. When budgets are tight, it can be easy to reach for the product with the lower sticker price. But is it really less expensive?

Product A calls for diluting at 8:1. This makes a total of 9 gallons of ready-to-use solution at a cost of $2.22 per diluted gallon. The label on Product B states “dilute at 16:1” for a total of 17 diluted gallons at a final cost of $1.76 per.

Product B with the higher price is actually a much better value and will be easier on your budget.

Hint: check with your distributor to see if they offer discounts on volume purchases. You may be able to save even more by buying a case or multiple cases at one time.

I just showed you how to save some money when purchasing your cleaning supplies. Maybe I can also save you much of the time, or at least put your time to better use.

A diluted gallon of pre-spray should be enough to clean about 250 square feet of carpet (of course, this will vary depending on the soil level and the density of the pile.) Using the above example, the diluted gallon of pre-spray that cost $1.76 costs you less than 1 penny per square foot of carpet cleaned!

What is the best use of your time: shopping around to save a little on a gallon of pre-spray, or spending that same amount of time marketing to new clients?