The School of UV
This is another great article from the archives of Aqua Magazine.
An insiders view on Ultra Violet Sanitizing Systems
For nearly two decades I have been spec’ing UV sterilizers, all the while never fully understanding how to select the correct device for each situation. Manufacturers have beautiful colorful brochures and detailed operational manuals, but for all of my experience and education, I still needed UV explained to me in simple terms.
So I called Marty Fisher, U.S. commercial sales manager for Delta UV, to enlighten me. I’ve learned totrust Marty’s knowledge on a range of subjects, and with his recent work educating the industry on the specifics of proper UV use, he seemed a perfect choice for my query. What he provided was a crash course in understanding what UV really is and how to navigate the various devices on the market.
I started by asking him to define what UV really is and how it affects the water in our projects. I knew of UVA and UVB light from suntan lotion labels, but I learned that our industry utilizes UV-C to treat the water we swim in. As public health codes have started to demand UV as a water sterilizer and the market has begun to expand, the topic is coming up more often at my company. New York State requires UV for public pools, waterparks, splash pads and other public baths and California mandates a complicated set of rules for all interactive water feature installations in every county in the state. I knew there was a need to update my knowledge base on these vital products and why we need them.
My biggest misconception about UV was that it actually kills pathogens like algae, bacteria and viruses. Actually, UV’s primary function is to sterilize by scrambling the DNA of these microorganisms so they cannot propagate and grow. UV is often used as a partner to halogens like chlorine and bromine since it can reduce halogen use, and therefore reduce the formation of chloramines and bromamines as well.
Marty clarified another large misconception that I had about the pressure rating of UV units. I assumed that this referred to the pressure of the operating water system but he set me straight — it is the internal UV bulb pressure. The higher the pressure, the more costly the system, but the more it can do for a project. So medium-pressure bulbs are more effective at eliminating chloramines than lower pressure, but at a price.
MAKING DOLLARS AND SENSE Another big economic question is why to use UV at all in our water projects if chlorine is such an effective sanitizer? Marty’s easy answer is cost, but just as important is its ability to reduce cryptosporidium, legionella, streptococcus, algae and many other bacteria and viruses. After doing the math on bulb replacement versus the costs of buying chlorine, we figured out that the financial benefits weigh in favor of UV for appropriate bodies of water. Besides, lowering the levels of chlorides in water has a widespread benefit to water quality and costs savings. The moral of this story is that UV is a tremendous partner to other stable halogens that stay persistent in water when a mechanical system turns off periodically. Besides the growing legal requirements for its use, there are plentiful reasons to apply this expanding technology in water projects.
Personally, after Marty’s explanations of the benefits and how best to spec units, we are now likely to see more UV units on our projects.
Article is sourced from Aqua Magazine February 2016