What does F71, F73, F59 mean?
Tanning lamps come in several different sizes. The most common sizes are F71, F73 and F59. Other sizes, such as F72, F74, F78 and others also exist. The "F" number stands for "fluorescent", and the number is the nominal length, although this doesn't line up nearly as well as you would think. An F71 is actually about 1/8 of an inch longer than a F72, for example.
The lamps also come in two different styles: RDC and bi-pin. RDC stands for Recessed Dual Connector, or the equivalent. In reality, the RDC is just a cap that fits over the bi-pins, and allows it to be used in a different (and more expensive) lamp holder. In general, a size comes in either bi-pin, or RDC and not both. There are some very rare exceptions, such as Peacock systems that used a proprietary F73 bipin. 99.99% of the time, F71, F59, F78 are all bi-pin, F60, F73, F74 are all RDC (ie: they have the black caps over the pins).
Example lamp ends showing RDC (F73) and bi-pin (F71) tanning bulbs.
Some lamps use the number FR71, adding the R. This means they have a reflector built inside the lamp. If the lamp is 100 watt, it might also be informally referred to as a RUVA (Reflector UltraViolet A). If it is a 160 watt or higher lamp, it might be referred to as a VHO-R or VHOR. (Very High Output - Reflector). The term VHR is actually a trademarked name of Cosmedico, Ltd. and only refers to their brand of VHOR lamps.
An F71 lamp (or any other size) can come in several different wattages. The 100w is the most common, and called HO, or High Output. VHO are the 140w to 200w versions. (Note the dropping of the letter R if the 160w lamp doesn't have a reflector built inside).
Another easily overlooked number that is used for sizing tanning lamps is the T factor. Most tanning lamps are measured as a "T12" The T number is the diameter of the lamp, in 1/8th inch increments, thus a T12 lamp is 12/8ths of an inche (1.5 inches) in diameter. Almost all full size tanning lamps are T12. Shorter, 2 foot bulbs used for special face tanning in a small number of beds may be a T5 (5/8th of an inch in diameter).
FR71T12HO means an F71 lamp, with reflector, 100w (the HO part) and is 1.5 inches in diameter. Because it is a F71 class lamp (F71/FR71) then we know it is a bi-pin lamp. Much of the time, the HO part is left off. Usually, if the lamp doesn't say VHO or HO, then it is an HO, or 80w/100w lamp.
FR73T12VHO means a F73 lamp, with reflector, 160W (or more), with the RDC caps on the ends.
Final note: Sometimes you will also see other codes mixed in, such as F71T12BL50 or F71T12/PK/50 which means a 100w, 71 inch lamp with blue phosphor (BL) or pink phosphor (PK) and a 5.0 UVB rating (50).