Ask Wolff


Some lamp manufacturers list a rated life for their tanning lamps. How is this determined?

Good question. Most manufacturers list a rated life for their products, but few say what it means. Is it when you should expect the lamp to burn out? Is it just a number chosen to justify their competitive claims? Is it when the lamp has lost half of its output?

First, let’s define ‘life’:
  • Physical life – The average time until burn-out (lamp won’t light) in the expected application. You should rarely experience sunlamp failure if you employ a well-designed-and-constructed lamp in well-designed-and-constructed bed operated per the bed manufacturer’s recommendations. Wolff does not ‘rate’ the physical life of its sunlamps.
  • Service life – The average time until the lamp’s output has degraded to the point where it is not an effective tanning lamp. At Wolff, we rate service life as that point where the lamp’s UV output has reached 70% of its initial level. A well-constructed sunlamp, properly applied, will be ready for replacement due to this natural output (phosphor) depreciation well before it fails to light.

Here are some things that will affect physical life and/or service life of sunlamps in your business:

  • Heat – running lamps at high temperatures shortens physical life and service life. Some beds simply treat lamps better than others, thermally speaking. Increasing input voltage (maybe with a buck/booster) beyond the bed manufacturer’s recommendations increases heat; so do dirty fans/airways, hot rooms, etc.
  • High current – some equipment ships with ballasts that operate at higher currents than normal, which can negatively affect physical life and service life.
  • Keep lamps, reflectors and acrylics clean. Not only does this aid in removing heat from the lamp chamber, it will increase the output of your system even if the accumulated dirt you remove is not visible. Bed maintenance affects physical life and service life.
  • Poor starting – more than just a few ‘blinks’ at starting (assuming your equipment uses the more popular pre-heat choke ballast) drastically increases the wear on lamp cathodes. When cathodes are depleted of the emissive material that actually starts the lamp, the lamp will not light. Low input voltage can cause poor starting, as can old/defective starters… this is a big one: replace conventional glow-bottle starters every one or two lamp changes. Poor starting affects physical life but not service life.

Because our sunlamps are almost always due to be replaced before they actually fail to light, and because UV maintenance is so much more important to the salon operator, we’ll discuss Service life. We can’t speak to the methods used by others to determine service life ratings, but we can explain our procedures.

Sunlamps experience their sharpest decline during the first 50 – 100 hours. Thereafter, output declines more gradually until the lamp is no longer effective. This is a natural characteristic of fluorescent lamp technology that employs phosphor to create ‘light’. The rate of decline speaks to product design and quality decisions, and to manufacturing competency.

Many confuse service life with physical life. Service life is not substantially affected by the number of lamp starts, so we test ‘maintenance’ in continuous burning mode to save time. The lamp aging area does not benefit from any special temperature control; just enough cooling is added so that employees can work in the area for short periods. Every production lot of every Wolff sunlamp has a number of lamps pulled for aging to 100 hours with results compared to the specification. After 100 hours, future maintenance is highly predictable. A portion of these 100 hour lamps are run out to 1,000+ hours, with interim testing at certain points along the way. Aged lamps are destroyed, as are lamps missing specifications.

The analysis of years of data result in Wolff’s published Service life ratings. It is impossible to duplicate the varied conditions found in the field (at the salon), with many different pieces of equipment from different makers operated differently in 30,000 varied locations across the country. Get and use an economical hand held UV meter and replace depreciated sunlamps before you get customer complaints.