Problem Solver - August 2009
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Protecting Aquatic Facilities and Patrons

Ultraviolet treatment systems for recreational swimming environments have gone from a rare sight to a common buzzword, but with the increase in interest, there's also been an increase in the number of suppliers who are not putting out good information.

How can you wade through this misinformation to ensure you're getting the right solution for your facility—one that will protect patrons? Do your homework.

Q: What do I need to know about the lamp technology of my UV system?

A: While low-pressure (LP) technology has been successfully employed in drinking water systems, it does not work as effectively in swimming pools. This is why manufacturers have developed medium pressure lamp technology for the recreational swimming pool market.

LP lamp technology is simply not suitable for both disinfection and chloramines destruction, for various reasons. As just one example, the water temperature of pools has an impact. At around 80 to 85 degrees, with spas in the 95 to 104-degree range, pools and spas are significantly warmer than the optimal temperatures under which LP lamps work best—68 degrees. At temps above that, the UV output of LP lamps drops significantly, because the lamps' relatively low surface temperature is impacted by the warmer water. Medium pressure lamps operate at a much higher temperature. That means they work effectively in a greater range of temperatures with no effect on the UV output.

Q: We were told that a study confirmed that LP technology is more effective though. What's true?

A: It's important to review the results of research objectively, rather than citing portions of research to advance one's own interests. Several manufacturers have cited a study from Duke University in North Carolina, titled "Impact of Chlorine and Monochloramine on Ultraviolet Light Disinfection," extracting data to make the claim that LP is more effective. The problem is that they fail to cite the conclusion of this study or the conditions under which the study was conducted. The study involved dosing from 300 mj/cm2 to 1,500 mj/cm2 to find out if UV will degrade chlorine and monochloramine. The UV dose range for chloramine destruction and disinfection is from 40 mj/cm2 to 60 mj/cm2 in swimming pools. The ultimate conclusion of the study was: "Chlorine and monochloramine in water decay steadily when exposed to monochromatic (LP) and polychromatic (MP) UV light. However, the total decay of chlorine and monochloramine are relatively small in the UV dose range that is generally applied for disinfection (15 to 130 mj/cm2)." In other words, the assertion that MP lamps burn more chlorine than LP lamps ignores the actual findings of the study as they relate to the actual standard usage of UV systems in swimming pools.

Q: So what do I need to do to get the system that will work best for my facility—one that's both cost-effective and also provides the risk management I need?

A: Simple, ask for references from your manufacturer. If a company makes a statement, ask for third-party documentation of that statement. When they size a model, ask how they determined the size. Find out if they are an authorized distributor for startup, training, parts and service. After all, once you own the system, you want an ongoing partnership with someone who will service the system as well.

Ask for a typical service agreement, so you know what the costs to maintain the system will be up front. Ask if the manufacturer has UL and NSF approval for swimming pools. Find out if the control panel is suitable for use in a wet-chemical plant room. Find out how many systems they have installed. Ask for and demand a written warranty. And finally, if the unit must be validated per state code, require a validation certificate with the system.

Engineered Treatment Systems: