Posted on July 6, 2014
We are often asked about the issue of heat build-up inside a UV disinfection unit. After all, the UV lamp is on 24/7 and will over the course of several hours, warm up the water inside the UV chamber.
This happens only when there is no flow in the system (such as overnight) when the water just sits in the UV chamber and collects some heat from the lamp.
It's important to know that the heat build-up inside a typical UV chamber after several hours of no-flow is relatively small. The water may flow slightly warm for the first few seconds after several hours of no-flow conditions, and may be noticeable at the faucet as water is drained from the UV system and put to use.
When using a UV Monitoring system within a typical UV water treatment system, it is possible that the heat build-up inside the UV chamber could trigger nuisance alarms from the UV Monitor. This happens because the UV monitor is sensitive to heat build up and warm water may fool the UV sensor into believing that the system is not functioning properly, and may therefore trigger false alarms.
The nuisance alarm issue is easily managed by using a heat-sensitive purge valve on the outlet of the UV unit. This non-electric valve is set to open as the temperature inside the UV chamber rises, and as it opens it will drain the warm water from the UV chamber. At the same time, new cool water rushes in from the supply system, thereby cooling everything down and avoiding nuisance alarm conditions.
For applications using a UV Monitoring system, or for applications that cannot tolerate warm water flowing from the UV, a temperature sensitive purge valve is a simple and inexpensive option that will keep your UV system operating at peak performance.
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