Rethinking UVC LED Lifetime Requirements for Disinfection Using Operating Hours


By Klaran

In Asian point-of-use water markets, a real and genuine concern for the microbial quality of tap water is spurring explosive growth for countertop and portable consumer and commercial water purification products. Both startups and established brands are looking to capitalize on this trend. Startups, driven by an innate need for innovation and differentiation and without the legacy bias toward germicidal lamps, tend to move directly to evaluate and adopt UVC LEDs.

For decades, established water purifier manufacturers have relied on low-pressure germicidal lamps to provide proven UV disinfection. However, in August 2017 the Minamata Convention on Mercury entered into force with the stated goal of phasing out mercury in everyday products. These potential regulatory barriers, natural consumer preference for non-toxic products coupled with competitive pressure from start-ups provide a strong motivation to water purifier OEMs to consider UVC LEDs.

Low-pressure germicidal lamps traditionally used in these markets are typically associated with lifetime claims of 8,000 to 10,000 hours. So it is understandable why engineers would ask or expect that UVC LEDs achieve similar or longer lifetimes. However, when looking at the specifications for these lamps, this lifetime is only achievable with a very limited on/off cycle rate (and most often 24/7 operation) with annual lamp replacement to ensure reliable disinfection performance.

As a solid-state device, UVC LEDs can be cycled on/off tens of thousands of times with little or no observable difference in degradation performance. In addition, UVC LEDs offer a near instant capability to provide its full rated output, requiring no warm-up time. These abilities mean that LEDs can be used in an on-demand fashion, accumulating operating hours only when “on” and providing their disinfection function without penalty.

Engineers considering next-generation products that avoid annual lamp replacement without sacrificing reliable disinfection performance will routinely ask whether UVC LEDs can achieve 25,000, 40,000 or even 100,000 hours. However, upon understanding the on-demand capabilities of UVC LEDs, the conversation quickly shifts to considering actual use cases for water dispensers.

For example, while commercial point-of-use systems like soda dispensers may be plugged in all the time, they typically perform less than 200 hours of actual water purification per year. Over the typical 5-year product lifespan of a commercial water purification system, a low-pressure germicidal lamp would require five lamp replacements while constantly remaining on, consuming energy and generating waste heat. In contrast, an LED-based system would expect to last the full 5-year lifetime of the product and accumulate less than 1,000 hours of use.

In the case of consumer markets, high-end point-of-use systems are sized to provide up to 6,000 liters of purified water a year, while more budget-friendly options providing even fewer. With a bottle or glass filling rate of 2 to 4 liters per minute, this equates to annual LED operation of 25 to 50 hours, respectively for high-end purifiers. Over the 10-year lifetime of a typical consumer appliance, a low-pressure germicidal lamp solution would require 10 lamp replacements. In contrast, an LED-based system would operate for the full lifetime of the appliance and accumulate less than 500 hours of use.

Water purifier companies want to differentiate their product portfolio, and on-demand UV disinfection for the full lifetime of the product is now a viable option. By taking advantage of the high cycle capacity of UVC LEDs, product designers can integrate this capability today and deliver water hygiene for the full lifecycle of their products.