We recognise that the end-of-lamp-life (EOLL) of medium-pressure UV lamps can vary from between 1,500 to 10,000 hours (depending on the manufacturer and lamp operation).  

To better characterise UV lamp lifespan, Nedap performed a field test with several popular medium-pressure lamps in cooperation with Heraeus Noblelight GmbH.  In these tests, the lamps were powered by high-frequency lamp drivers (>20 kHz). These tests showed that many medium-pressure UV lamps could operate for up to 10,000 hours with a UVC output depreciation of less than 15%. 

Medium-pressure lamps are widely used in industrial technologies, including printing (ink curing) and water treatment (disinfection); for instance, for water treatment systems, the quartz envelope determines the operational lifespan. Quartz glass lamp manufacturers recommend replacing the UV lamps after 5,000 hours of operation. 

The operational efficiency of UV lamps is defined by the lamp manufacturer. It depends upon several factors, including UV lamp specifications, application, and operating conditions. For example, UV lamps used in curing applications are switched on and off more frequently. As a result, the UV output decreases faster, resulting in a shorter lamp lifetime. 

UV lamps used in water disinfection solutions operate continuously. Constant lamp operation has a positive impact on the lamp life, with a decrease of 30% in UV output at end-of-lamp-life. This level of efficiency is still in accordance with the manufacturer’s standard. Overall lamp lifetime and efficiency losses are also affected by water quality and the liquid’s transmittance. Additionally, variations in water flow affect how the lamps are used. It is common to find over-dimensioned systems, where lamps operate at 80 – 90% of their capacity for optimal efficiency.  

Lamp drivers that offer flexible step-less dimming are integral to building more energy-efficient systems. Likewise, they enable operators to control UV light levels, which can reduce unwanted and potentially damaging side effects.  

When testing and validating UV systems, we dim UV lamps to 5% to simulate dirty UV Quartz sleeves. This makes testing easier and more accurate, which reduces time spent during the inspection process. 

UV lamps used for water disinfection applications are commonly dimmed by up to 90% during the lamp’s lifetime. At the end of lamp’s-lifetime, this is often pushed to 100% to extend the overall lifetime of the lamps (for constant UV output).  

Dimming is commonly applied in UV systems where fluctuations in UV output are required. In wastewater plants, for example, UV lamps are often dimmed to reduce energy usage. In these cases, minimising lamp ignitions can extend lamp lifetime. 

However, extensive UV lamp dimming (below 60%) has a negative effect on the lamp lifetime. This occurs when the lamp becomes too cold.  

During normal operation, temperature control plays an important role in optimising UV lamp lifetime, performance, and efficiency.  

Nedap’s newest 4/8 kW medium-pressure UV lamp drivers provide operators with greater control than ever before. Using a PC lamp driver tool and ModBus interface, you can set the UV lamp power, nominal lamp current, maximum lamp current, maximal lamp warmup current, and warm-up to run. 

Nedap’s UV lamp drivers are designed to work with all major manufacturers of UV lamps, including Heraeus, Hanovia, Alpha cure, LSI, Atlantic Ultraviolet, and Signify / dr fischer. (To work effectively, the lamp power and current must match the lamp driver.)