1. Base--connects the lamp to an external source of power.
2. Lead-in Wires--connect the base to the cathode, which emits electrons during lamp operation.
3. Mercury--atoms in the form of a vapor in the lamp that are struck by the electrons and excited from their ground state to a higher state, from which they emit a UV photon with a wavelength of 254 nm.
4. Phosphor--absorbs this UV and converts it to longer wavelengths (usually visible light). It is coated onto the inside of the lamp during lamp manufacturing.
5. Stem Press--is a cathode support structure as well as the means to hermetically seal the lamp ends.
6. Exhaust Tube--is the means of introducing the fill gas and mercury into the lamp during processing. It is then closed off.
7. Fill Gas--is an inert gas which aids in starting and operating the fluorescent lamps.

UVB To UVA Ratio

There are many myths or misconceptions in the marketplace today about tanning lamps. How often should lamps be changed or cleaned? What percentage is best for the UVB/UVA ratio? Which lamps tan better and quicker than others? These are only a few of the many questions that make an intelligent buying decision a rather difficult task.

However, as difficult as the task may appear, once a basic understanding of light and its relation to the tanning process has been established, tanning lamps are no longer a complicated or ambiguous mechanism.

Although light appears to be a simple concept, it is quite complex in structure and can be broken down into eight different categories that comprise the entire light spectrum--Cosmic Rays, Gamma Rays, X-Rays, Ultraviolet Rays, Visible Rays, Infrared Rays and Radio Waves.

With indoor tanning, we are primarily interested in ultraviolet rays that are invisible to the human eye and potentially the most dangerous. Within the ultraviolet spectrum, there are basically three different rays with which we must be familiar--UVA, UVB and UVC.

UVC rays have the shortest wavelength of all ultraviolet rays and, therefore, are potentially the most dangerous. Experts maintain that all UVC rays are absorbed by the earth's atmosphere, but there is currently a debate going on between scientists as to whether the ozone layer of our atmosphere (the layer which absorbs UVC rays) is breaking down and allowing UVC rays to penetrate to the earth.

Our skin color is determined by the skin pigment melanin, the presence and quality of which are determined by hereditary factors. In people with darker skin types, the pigment grains are larger and distributed more.

Radiation without any UVB is another extreme. This would require such a high radiation intensity that the radiation would prove an unpleasant and even intolerable experience. For that reason, FDA regulations control output according to spectral intensity, rather than percentage.

As a salon owner, you should seek a ratio of UVB to UVA that offers the minimum risk of sunburning and yet allows a reasonably short period of radiation. Most tanning lamp manufacturers keep this concept in mind.

Once a tanning bed is manufactured and its exposure schedule is determined, the FDA only authorizes the use of lamps with similar output for use as replacements in that particular bed. The manufacturers of replacement lamps are required to demonstrate to the FDA that their lamps meet the compatibility requirements specified in the code for them to be marketed as replacements for other lamp models. They are shipped with labeling indicating the models of lamps for which they may be used as replacements.

Recertification

Alternately, the FDA permits the use of what would be non-equivalent lamps in equipment, provided that testing is conducted and filed with the agency to determine a new exposure schedule for the unit with the new lamps. This is known as recertification. The new exposure schedule then is shipped with the lamps and, as long as it is observed, the unit remains in compliance with the code. Some lamp manufacturers are in the process of conducting such testing for models in their particular lines so they may be used with most popular models of tanning equipment.

If there are any questions regarding the type of lamps that should be used for replacements, a call to the manufacturer should be placed. Manufacturers of lamps are required to submit evidence to the FDA that authorizes them to claim compatibility with other lamps and, thus, allows for the replacement as well. A salon owner should be very careful to make sure that he replaces the lamp with compatible lamps approved by the FDA.

The Effects Of External Factors On Tanning Lamps

The overall effectiveness of a tanning unit ultimately depends on the irradiance that actually reaches the exposed skin, which is not necessarily the same as that originally produced by the lamp. The total irradiance on the skin is influenced by a number of external factors including the distance between the radiation source and the skin, the optical components of the equipment and the specific working conditions.

Irradiation Distance

In the case of most tanning beds and booths, the irradiation distance is determined by the construction of the tanning unit and cannot be changed by the user. In those cases where it is variable, the user should be aware of a basic relationship: The greater the distance, the less the received irradiation. Usually, the instructions accompanying such equipment advise the user as to the best distance for operation.

As a rule of thumb, it can be recommended that the distance not exceed 20 cm to 30 cm (approximately 8 inches to 12 inches) with a low-pressure unit. The received irradiance decreases considerably at greater distances and becomes more and more ineffective.

With high-pressure units, the best distance may vary from unit to unit in order to avoid any unpleasant irritation of the skin as a result of excess heat development.

Optical Components

There are three specific optical components in a tanning unit: the radiation source itself, the external reflector and the filter system and/or acrylic sheet. In general, all of the optical components are installed by the manufacturer, so the user has only very limited possibilities to make alterations, except for replacing the lamps or acrylic sheet.

The Radiation Source

Commonly, the radiation source produces non-directed rays in different wavelength ranges. The degree of radiation intensity at certain wavelengths is derived from the relative spectral power distribution or, in short, from the spectrum. While the spectrum largely depends on the lamp type, the actual output performance also is determined by the working conditions.

In general, high-pressure tanning lamps, also referred to as metal halide lamps, produce a wide spectrum ranging from short-wave ultraviolet rays of about 250 nm up to rays in the infrared range. For that reason it is not possible to use these lamps without additional filters. As a consequence, other optical parts of high-pressure equipment affect the spectrum as well as the output to a considerable extent.

In contrast, the spectrum produced by low-pressure equipment is restricted largely to the tanning UV range from 300 nm to 400 nm. Consequently, any additional filter systems to a large are unnecessary. Therefore, the performance qualities of low-pressure tanning units are dependent primarily on the spectrum and the output of lamps used.

External Reflectors

The reflector is designed to focus and concentrate the lamp's rays in the desired direction. In order to do this as effectively as possible, which means without any significant loss of intensity and without spectral changes, the distinct shape of the reflector and the material of which it is made play important roles.

Under normal conditions, neither the shape nor the properties of the reflector material change substantially with increasing operating time. However, the reflector surface dirties easily which leads to a loss of intensity, so regular cleaning is necessary to maintain its effectiveness. Dusty or stained reflectors can reduce output performance up to 20 percent and more.

Filters

The purpose of filter glass is to eliminate or reduce specific rays that are produced by the lamp but are not desirable. With increasing operating time, the filter may age and its filtering properties may undergo changes, usually resulting in an overall loss of intensity. However, extremes of temperature also may alter the filter's effectiveness, making some filters more or less transparent to short-wave UV rays.

Acrylic

The acrylic in low-pressure units usually separates lamps from the user. The sheet's ability to transmit almost never alters the spectral distribution and at the most can cause a reduction in total intensity. A new sheet should affect the total irradiance by no more than 10 percent.

After hundreds hours of operation, the acrylic can age, resulting first in less transmission of UVB rays and later to decreased UVA output. If the UVA reading obtained with the sheet in place shows a 20 percent or greater decrease in output as compared to the reading at the same distance from the naked lamps, the sheet is clearly over-aged and should be replaced. At that point, it also may show some yellowing of cut edges.

Both filter glass and acrylic sheets should be cleaned regularly in order to prevent reduced output. Because of static charges, dust constantly will adhere to filters and acrylic and impair transmission of tanning rays. Consult your acrylic manufacturer to determine the longevity of your shield.

Working Conditions

Operating conditions such as electrical factors and especially heat can have a considerable influence on the output and operable lifespan of tanning lamps.

Electrical Conditions

Both low-pressure and high-pressure tanning lamps are developed for closely defined electrical working conditions. In order to ensure reliable performance, precisely suitable ballasts are required to stabilize current flow for proper operation.

In the case of unsuitable ballasts, it can happen that the lamps are operated with a higher current than assigned. Although the initial effect may be a higher output performance, the lamp will run continually in an overloaded state and its operable life will be decreased or, in extreme cases, it could prematurely fail altogether. Further, the operating temperature of the lamps will be increased which could create problems for the unit's cooling system.

On the other hand, a lamp current that is too low will proportionally decrease the produced radiation intensity. A similar situation also exists in regard to electrical voltage. Therefore, it is very important to follow the lamp manufacturers' recommended electrical operating data to maximize lifespan and output.

Thermal Conditions

Because the radiation produced in both low- and high-pressure tanning lamps results from an electrical discharge, the pressure of the gas filling inside the lamp must be maintained accurately in order to obtain the optimal radiation intensity. Since gas pressure is directly dependent on the temperature, lamps should be operated very close to their temperature optimum.

In the case of low-pressure lamps, the optimal operating temperature lies at about 104 degrees Fahrenheit. Either higher or lower temperatures will lead to a decline in produced radiation intensity. A loss of intensity on the order of 5 percent to 10 percent caused by thermal deviation of about 50 degrees Fahrenheit is not unusual in units with unbalanced cooling systems.

High-pressure lamps can handle far heavier heat loads than their low-pressure counterparts despite their smaller dimensions. Therefore, with high-pressure lamps the situation is different. Premature failures usually are linked to overloads of thermal or electrical nature. High-pressure lamps reach their optimal operating temperature at about 1,472 degrees Fahrenheit.

Below 1,292 degrees Fahrenheit the spectrum that is produced is incomplete because the metal halides in the lamp have not evaporated yet. Thermal overloads, on the other hand, inevitably lead to early failures. At temperatures above about 1,742 degrees Fahrenheit, the quartz glass softens and allows the lamp to expand, resulting in deformation. The changes in the size and shape of the lamp alter the pressure of the enclosed gases, making further operation impossible. Such defects often are observed in facial tanners as a result of insufficient cooling.

Although only a few of the effects of external factors on tanning lamps are discussed herein, it becomes obvious that manufacturers of indoor tanning units must consider a number of specific technical requirements in designing equipment to produce optimal tanning effectiveness. Optical, as well as electrical components and the operating conditions of the unit as a whole, must harmonize with one another to maximize the output performance of the lamps.