What is PIR and Why Should You Care About it?

Dilution ratios are out. PIR is in.


What is PIR?

PIR, or panel impact ratio, is the percentage of a chemical exiting a foam cannon or sprayer when diluted with water. Many of the Bilt Hamber products in our store use this method to measure out their product since it is a more accurate measurement than dilution alone.


Sounds like dilution ratios to me!

You’re right! Dilution ratios do play a part in this calculation. However, PIR takes into account the water coming out of your foam cannon as well as the water in the foam cannon bottle. This makes your calculation more accurate, which is especially important when considering PIRs of 0.5%. Because each foam cannon and each pressure washer are a bit different, there is not a “one size fits all” answer to how much chemical you should put in your foam cannon. What if your foam cannon has dual agitators? What if your pressure washer has four plungers instead of three? These are all things that affect PIR.


How do I calculate PIR?

The nice thing about PIR is you only have to calculate it once, and then you can apply your numbers to other products that use PIR. Here is an example of how to calculate a 2% PIR with Bilt Hamber Touch-Less.

Step 1. Start by filling your foam cannon with water. Most foam cannons on the market have a 1000 ml capacity, so we will use that for our measurement. Ensure your foam cannon is fully open, allowing for maximum foam. With the pressure washer hooked up and turned on, spray the foam cannon into a bucket until the foam cannon is empty. Once empty, measure the amount of water in your bucket.

Step 2. Let's say your foam cannon sprayed three gallons into the bucket. Three gallons is equal to 11,356 ml. We are using ml since that is how the volume in your foam cannon is measured. Now, let's calculate a PIR of 2%.

Step 3. Take 11,356 (volume in bucket) and multiply it by 0.02 (2% PIR). This will give you 227.12 ml. This is your CHEMICAL volume.

Step 4. Put 227 ml (round as needed) into your 1L foam cannon, and then top off with water to the 1L mark. You’re now using Touch-Less at a 2% panel impact ratio for your pressure washer setup.

Step 5. If you want to use 1% PIR, multiply your volume by 0.01. If you want to use 0.5% PIR, multiply by 0.005.


What if I am not using a pressure washer?

If you are using a garden hose foamer, you can follow the same process previously described. If you are using an IK Foamer or Marolex Foamer, the process is much easier. Since there is no outside water source besides what is in the bottle, you can treat it like a regular dilution. For example, if you had a 2L Marolex Foamer and wanted a 2% PIR, you would add 40 ml of product to 1960 ml of water, and then it’s good to go.


What if I don't want to do the math?

For ease of use, we have an easy-to-use calculator below. With it, you can measure the water in your bucket in a variety of ways. Even if you want to just weigh it, it will calculate how many ml to add to your foam cannon!


OG PIR Calculator