Do sunlamps depreciate over time or just with use? Do they have a “shelf life”? Great questions!
First, let’s talk about how a low-pressure sunlamp works. Inside the glass tube is a thin phosphor coating and a small amount of inert gas and mercury. When power is applied to the lamp, emissive material (a chemical coating) sputters from the cathodes at each end and inside the lamp. These emissions assist in the ignition of an electric arc between the cathodes at opposite ends. The electric arc vaporizes the mercury, contributing its properties to the arc stream and “exciting” the mercury’s ultraviolet energy, causing it to fluoresce.
As you can see, a sunlamp is composed of glass, metals, gas and phosphors. When we at Wolff System speak about performance depreciation of sunlamps, we are referring to the known characteristics of the phosphor within the sealed glass tube making up the lamp.
When a lamp is started and operating, the depreciation process begins. The phosphor will weaken as the lamp continues to operate, producing less UV output. This is a natural result of the interaction between the phosphor material and the electric arc from one end of the lamp to the other, plus a phosphor-weakening factor is present in the form of heat. This natural decline in output (from the degradation of the phosphor’s efficacy) leads us to the service life ratings we publish … the end of a lamp’s service life equals that point where UV output has declined 30% from when the lamp was new.
Once the lamp is turned off, the depreciation process is halted until the next time the lamp is started. There is nothing organic in a lamp that will fail or spoil over time, such as with bread or milk. Our service life ratings speak to lamp-on hours, not elapsed time since the lamp was installed. In some tanning facilities, it may take ten years to collect 1,000 hours on a lamp; a busy salon may do that in a few months. Burn a lamp for one hour then turn it off, bury it in a time capsule and unearth it 100 years later – it still has only one hour of use and it is the same as when it was put away.
Likewise, there is not a shelf life on tanning lamps sitting in inventory because the components used in the
manufacturing process do not expire, age, deteriorate or spoil. The production date codes simply identify when the lamp was produced and is only used as a reference by the manufacturer, to comply with FDA regulations, and as a component of quality control processes.
Also, it doesn’t matter if the lamps are stored in a vertical or horizontal position. If stored vertically, you may want to be sure that the boxes are propped up securely to keep from being knocked over. We are also asked whether lamps can be stored in a cold garage. This is not a problem; however, it may take the lamps a few minutes to adjust to the temperature change and fully light when installed in the tanning unit. Once it adjusts, it’ll work fine.
Do sunlamps depreciate over time or just with use? Do they have a “shelf life”?
