[Original Post was started at http://www.tantalk.com/ubb/Forum1/HTML/000101.html ]Ginger:Two or three years ago a company came out with an ingenious sunbed that I will describe to set the stage for this discussion. This sunbed had 28 lamps and the salon owner could select the MTI (maximum timer interval) for the unit. That means that it could be a 10, 15, 20 or 30 minute MTI depending upon the lamps that were used. IF the unit would have had 30 or 32 lamps instead of 28, we would have most certainly considered purchasing this unit.The beauty of this unit was that a salon owner could have installed it as a 30 minute MTI unit and later change it to a 20 or 15 minute unit if conditions changed OR made one unit a 10 minute MTI if necessary.One of these days a smart manufacturer will pick up on this concept and take over the market!The deciding factor about the MTI in a tanning system (sunbed and lamp) is (1) the ballast used, and, (2) the lamp selected.1. The ballast can either be a "choke" or a "rapid start" and there are sunbeds currently available that use both. Listed below are the choices. (John: perhaps you can put this info into a "pretty" chart.)# Choke Rapid Start Lamp1. 80 w 800 MA 80 watt2. 100 w 1000 MA 100 watt3. n/a 1210 MA 120 watt4. 140 w 1500 MA 140 watt5. 160 w 1500 MA 160 watt6. 200 w 2130 MA 200 wattTherefore, if we have a tanning platform that has either 100 w choke or 1000 MA rapid start ballasts, we can have a 10, 15, 20 or 30 minute MET (maximum exposure time) system by selecting the appropriate lamp.If we have 100 w choke (or 1000 MA rapid start) ballasts powering the bench and 160 w choke (or 1500 MA rapid start) ballasts in the canopy, we would have a "hybrid system with 100 watt lamps in the bench and 160 watt lamps in the canopy. Once again, the actual MET would vary depending upon the lamp selected. USUALLY it is the canopy lamp that determines the MET because, even if the same lamp/ballast combination is used, the "thicker" acrylic in the bench means that there will be less UVR "transmitted" (%T) in the bench than in the canopy. However, IF a sunbed had a lamp in the bench that took 10 minutes to reach 4.0 MED (t-4.0) and a lamp that took 20 minutes to reach t-4.0 in the canopy, it would be a 10 minute system, not a 20 minute system. The important thing to remember is that the sunbed itself is nothing but an expensive (and attractive) lamp holder. It is the lamp selected that determines the t-4.0.The next "installment" will cover the use of hand-held radiometers.Don |