Every week you hear me ask for questions from you, The Scaling UP! Nation! and I am happy to report that you answer those requests. One of the topics that have come up from listeners of the show is for me to define why we do certain things in water treatment. Most of your questions have revolved around math.

Over the last few Pinks and Blues episodes, I have been answering a few of your questions about equations we all use, but don’t know where they came from. Let’s do another one today!

Today, we will be talking about the mysterious, **tonnage times 3** to find the recirculation rate. If you are trying to find the evaporation of a cooling tower, you need to know the recirculation rate. And, because being a water treater is never easy, you can never find that information. At least not easily. Because of this common issue, we have all used the common *“rule of thumb”* tonnage times 3 equals the recirculation rate. But why and where does it come from? That’s what we are going to answer.

**To calculate the evaporation rate, you usually use this equation:**

If you have ever wondered why we measure cooling in tonnage, it because it is based on a ton of ice. So, our equation is all about melting a ton of ice. **The image below shows how we get a chiller ton:**** **

A cooling tower not only has to take out the heat a chiller removes, but also the heat that the chiller creates in that process. **With all of that in mind, below proves how we get to tonnage times 3:**** **

So there it is, the math does work!

I hope that you can now confidently use this equation we have all been using for years. But now, since you understand the equation, it should bring more meaning to you.

**Timestamps**

Radical Polymers [0:00:10]

AWT Training [0:01:43]

Doing Math On the Podcast [0:06:46]

Evaporation Rate [0:10:22]

The Recirculation Rate [0:12:35]

Why We Use The Word “Ton” [0:13:32]

How To Get Tonnage x3 [0:20:05]

**Quotes**

“The more you give to this industry, the more that you will get back.” – Trace Blackmore

“When you let people know what issues you’re having, they can use their experience to answer your question in a different way that will allow you to solve them.” – Trace Blackmore

**Links**

**Association of Water Technologies**

Trace,

This is my first time listening to one of your PodCasts. Great job doing math using this platform! Your delivery was excellent! I will be back to listen to more.

Janet

Water Treater with Garratt Callahan

13 years in the industry and a review of WHY do we use that factor is always a good reminder. Thank you for rising the tide!