Q: Does higher lamp wattage equal better tanning capability, or just more power consumption?
A: The wattage of a fluorescent, low-pressure lamp is determined by the lamp design and, more importantly, by the ballast that powers it. All of this is influenced by the input voltage to the ballast/lamp system. In simple terms, the ballast will determine the system wattage, so installing a 100W lamp in a ballast with higher wattage (say 120W/1200mA) will result in approximately 120W of power consumption.
Wattage is primarily a measure of power consumption, not necessarily irradiance (output). Wattage is also a measure of heat. One watt = 3.412 BTU. British Thermal Units are a heat value standard, and you see this term commonly used in air conditioning system specs. Total wattage of your equipment at actual input voltage, including fans and other onboard electrical devices, tells you the BTUs of A/C required to handle the heat load. This is something to keep in mind if you are “upgrading” a few smaller beds to larger beds with more lamps/wattage/BTUs … your HVAC guy should be consulted to be certain your air conditioning is of adequate size.
In our industry, there is a move to higher wattage sunlamps versus the standards of 100W and 160W. The standard sunlamp envelope is F71/T12/Bi-Pin. In its 100W iteration, the internal environment of the lamp is tough; at 160W it is almost hostile. Increasing wattage further magnifies this effect, thus the shorter service life to be expected with increasing wattage due to amplified phosphor degradation and, to some extent, physical wear and tear. Increasing wattage will increase output of the lamps, but not in a linear sense. Increasing wattage (and heat) past optimal lamp design by 10% yields about 5% greater irradiance and 10% higher power use. Keep in mind that in each of these scenarios, the lamp is the same size, you’re just demanding more from it.
So, the answer to the question is: All other things being equal, increasing fluorescent sunlamp wattage results in increased output and power consumption. That is not to say that it’s wise to install 100W lamps in a 160W system … cathode and mount designs are very different for these two lamp styles, and this kind of misapplication will certainly disappoint you. Whether a sunlamp is a reflector or full-coat type, the wattage does not change due to the reflector … radiant heat is directed differently by reflector lamps, but there is not more of it.
All other things being equal, increasing fluorescent sunlamp wattage results in increased output and power consumption.
Since tanning equipment of any size (or wattage, or UV source) can only deliver a maximum session equaling a dose of four MED (Minimum Erythemal Dose), there are reasons for higher wattage:
- For aesthetic reasons, greater lamp irradiance allows for longer exposure distances so the unit can look the way the designer wants (or just be bigger).
- Also, in same size equipment with the longer exposure time, higher wattage/output lamps allows fewer lamps and other components, resulting in lower manufacturing costs and a lower cost for the equipment.
- Economically speaking, greater irradiance allows for shorter maximum session times in like-sized equipment, thus higher tanner throughput and revenue at the salon.
