Skip ahead to the Pressure Washer Dilution Calculator.
This seemingly simple subject is still the cause of confusion, and it was for me too. After having to figure this out two springs in a row I decided to write it down and share it. Consider this problem: One part pressure washer detergent should be mixed with 20 parts water for proper dilution (1:20). The pressure washer uses a fixed mixing ratio of 1:7 detergent to water. How should the detergent be pre-diluted so that the pressure washer delivers a spray with 1:20 mixing ratio?
It is easy to think that it is a simple algebra problem, using the equation 1/20 = (1/7) × MR. Not so! This would have worked had we used concentration instead of mixing ratio, however.
Definitions:
- Mixing Ratio, MR = solute / solvent
- Concentration, C = solute / (solvent + solute)
Mixing ratio is usually given as the inverse, solvent/solute, but either one works as long as we know which one we're using.
Concentration is often expressed in percent by multiplying C by 100%.
Pressure Washer Dilution
Theory, Using Mixing Ratio
The way to think about the problem is to think about the total quantities of detergent and water used. Let's say we want to prepare a p gallon jug of pre-mix detergent and water.
On the left hand side we have the desired final mixing ratio. On the right hand side we have the quantities of detergent and water in units of gallon, where d is the quantity of detergent in the p gallon jug. The (p-d) is the quantity of water in the jug, and 7p is the number of gallons added by the pressure washer while dispensing the content of the jug. If we set p=1 gallon, we solve for d and find that d=0.381 gal = 48.8 oz.
Theory, Using Concentration
We convert the mixing ratios to concentrations and we have...
...where C is the concentration of detergent in the pre-mix jug, C = d/p.
Solving for C we find that C=0.381 (or 38.1%). Multiply 1 gallon by 0.381 and we find that we need 0.381 gal detergent = 48.8 oz.
This type of problem is easier to solve using concentration rather than mixing ratios, but since directions provided with consumer products use mixing ratios (in the U.S. anyway) we will use them as well.
This calculator computes the amount of detergent needed in the pre-mix jug, using the given mixing ratios.
| Detergent | Water | | Final Mixing Ratio: | : | | | Pressure Washer Mixing Ratio: | : | | | Tip: Set to 1:0 for a general mixing calculation. |
Desired Volume of Pre-mix:gal
† | Pre-mix Concentration: | % | |
| Detergent: | gal†= | fl. oz. |
| Water: | gal= | fl. oz. |
The water volume needs typically not be measured since we can just top up the jug with water.
The calculator also works for mixing gasoline and oil for two-stroke engines, for example. Set the pressure washer mixing ratio to 1:0. Notice that this calculator works differently than the typical gasoline pre-mix calculator on the web in that you set the final volume of pre-mix rather than the volume of gasoline (or water) used.
†The unit here is intended to be gallon (128 fl. oz.) but it can be any unit including liter. The fl. oz. result only applies if the unit is gallon.
FAQs
The pressure washer uses a fixed mixing ratio of 1:7 detergent to water.
How do you calculate dilution ratio when mixing chemicals? ›
The procedure is straightforward: add the two numbers together and divide the total volume by that sum. For example, if your dilution ratio is 10 to 1 and you want to fill a 12-ounce bottle, you would add 10 and 1 to get 11. Then, divide 12 by 11 to calculate the number of ounces required for the dilution.
What ratio is a pressure washer with chemical injector? ›
What is the chemical injection to water ratio? The ratio that the chemical is diluted varies slightly from unit to unit. The most common ratios fall between 12:1 and 18:1.
What is the chemical ratio for power washing? ›
In general, a common ratio for pressure washing is 1 part sodium hypochlorite to 10 parts water (or a 10% solution).
What is the best mix for pressure washing? ›
The easiest would be 1:1 ratio of bleach/water with 2 oz of Dawn dish soap (blue one, without ammonia) for every gallon of mix. That mixture should be more than enough to take care of algae, mildew and dirt. The best all-around solution to soft wash a house is a mixture of bleach (sodium hypochlorite) and water.
What is the ratio of sodium hypochlorite to water for pressure washing? ›
You would need to combine one part sodium hypochlorite with four parts water, for instance, if you had a 12.5% sodium hypochlorite solution and wanted to make a soft washing solution with a 1:4 mixing ratio. You must use some basic maths to determine the precise amounts of each ingredient.
How do you calculate mixing concentration? ›
This can be calculated by determining the amount of solute in both original mixtures, adding them together, and then dividing by the total amount of solution. To be written as a percent concentration, the final concentration can be multiplied by 100.
How do you calculate dilution concentration? ›
We can relate the concentrations and volumes before and after a dilution using the following equation: M₁V₁ = M₂V₂ where M₁ and V₁ represent the molarity and volume of the initial concentrated solution and M₂ and V₂ represent the molarity and volume of the final diluted solution.
How do you find the dilution factor from concentration? ›
The dilution factor is the inverse of the concentration factor. For example, if you take 1 part of a sample and add 9 parts of water (solvent), then you have made a 1:10 dilution; this has a concentration of 1/10th (0.1) of the original and a dilution factor of 10.
How do you add chemicals to a pressure washer? ›
Before connecting the high-pressure hose, insert the detergent injector into the quick coupler mounted on the pump. Connect the high-pressure hose to the water inlet on the pump. Insert the clear detergent hose into the bottle of detergent. Make sure it stays submerged during the cleaning process.
Usually size 1.8 is good for 2-3GPM machines, size 2.1 is good for 3-5GPM machines, and 2.3 is good for 6-8GPM machines. If this all lines up then next you need to check your nozzle size. 3-5GPM machines will need a 30-40 orifice size nozzle in order to draw soap. 8GPM machines will need a 40-60 orifice size nozzle.
How do you use a pressure washer injector? ›
If you are using a hot water power washer then insert the injector where the water exits the burner or the hose reel. The rule of thumb is to insert it at the entry point of the pressure hose. This prevents all the components of the pressure washer from the harsh effects of aggressive chemicals.
What solution do professional power washers use? ›
Sodium Hypochlorite 12.5% (Bleach, Chlorine)
Sodium Hypochlorite, commonly known as bleach, is the most common and extensively used chemical used by commercial pressure washers. Our bleach is sold at 12.5%, which is stronger than other leading brands of bleach.
How much does a downstream injector dilute? ›
All downstream injectors will dilute your mixture.
In order to use a downstream injector, the end solution of the chemical being applied must be effective at dilution rates of 8-1 and higher.
What does 32 1 mix ratio mean? ›
Use a 32:1 gasoline to oil ratio. One gallon of gasoline combined with 4 oz of two-cycle engine oil.
Do I need to dilute cleaner for pressure washer? ›
Ready-to-use detergents can be added directly to your detergent tank as-is, and concentrated detergents need to be mixed with the appropriate amount of water to get a proper ratio.
What is mixing ratio 25 to 1? ›
If you're using a different brand of 2-Stroke oil, you'll need to mix at 25:1 (40mls oil per 1 litre fuel). Petrol has limited shelf life (as low as 30 days), so always mix with fresh regular unleaded purchased from a reputable large volume fuel supplier.
What is 50 mixing ratio? ›
Oil mix ratios explained
If your manufacturer recommends a 50:1 fuel/oil mix, it means you need 50 parts of gas to one part two-stroke oil. To mix one gallon of fuel at 50:1, add 2.6 ounces of two-stroke oil to one gallon of gas, as shown in the chart below.
