The frequency of changing a UV lamp for effective indoor air quality improvement depends on how you are using the system. Typically, a UV lamp being used primarily to disinfect the air circulating through a home or small office should be replaced every 9000 hours or approximately every 12 months. For people with respiratory conditions or other acute sensitivities, we strongly recommend keeping to an annual lamp replacement schedule for the best control of airborne microorganisms and allergens.
There are many factors that influence UV lamp life and how the lamp is operated and the lamp’s operating environment will ultimately determine useful hours of lamp life.
Besides producing UV light, mercury vapor lamps also produce visible light and infrared light. Actually, about 60% of the light produced is in the infrared spectrum. This is because of the high operating temperatures within the lamp. This heat, together with foreign materials deposited on the quartz, causes the quartz to vitrify or decade. This vitrification of the quartz will eventually cause the lamp’s intensity to diminish to a level where it is no longer suited for the application.
How the lamp is operated does influence the speed of vitrification. The quick addition or removal of heat generally increases the speed of vitrification. Therefore, the more times power is cycled on the lamp, the quicker the lamp decays. Starts also have another effect on vitrification. During startup, the lamp’s internal pressure is low. As pressure builds, the electrodes sputter off tungsten which is deposited on the inside of the lamp and further promotes vitrification. Excessive starts should therefore be avoided by batching your curing operations together.
Another factor influencing vitrification is how the lamp is handled. Any material deposited on the quartz, will cause the quartz to vitrify. This is especially true of the oils on your hands. You should therefore avoid excessive handling of the lamps and always wear clean cotton gloves when replacing lamps. Curing and drying operations also contribute to vitrification as the quartz is exposed to ozone, vapors, hydrocarbons, and volatile gases being emitted from the inks, coatings, or adhesives being cured.
Heat removal is another important factor influencing lamp life. Inadequate cooling and deficient heat removal creates excessively hot operating environments contributing as well to premature vitrification.
Replacing a lamp before it literally “burns out” may seem wasteful but not when it comes to UV light. After the first year, all UV lamps by their fundamental design will have lost nearly half of their germicidal effectiveness. That’s why, for air disinfection – where the target organisms are moving with the airstream and have a short exposure time – it is critically important to keep to your one-year replacement schedule.bio-growth, then the lamp can be replaced every two years – its maximum lifespan. This saves money (and the environment). UV lamps used for component irradiation have a stationary target: the mold or microbes that try to colonize on them. Therefore UV exposure time is much longer so less intensity is needed to prevent growth.
A UV lamp should not be kept running after 3 years. The UV system should just be turned off until the lamp is replaced, because it effectiveness is spent and it will simply waste energy. The excessive energy consumed by an aging lamp can cause the power supply to overheat, potentially causing a complete system failure.
Always remember to heed all warnings and never look at an operating UV lamp.