Powersportsunlimited - The most common type of lighting used in
paint spray booths are panel mounted fluorescent lighting fixtures. The
fixtures are actually mounted and recessed in the booth panels. These
fixtures are commonly Class I, Division 2 or Class I, Division 1 rated
fixtures and are third party listed for hazardous locations. Class I,
Division 2 locations are those where volatile flammable liquids or gases
are handled, processed, or used. Normally, they will be confined within
closed systems from which they can escape only in the case of rupture
or deterioration of the systems.
Powersportsunlimited - Panel
mounted design provides a simple and efficient means of installation.
These fixtures are typically constructed of either 18 or 20 gauge steel
construction. Coupled with a white baked enamel finish, a durable and
highly reflective fixture finish is created. A clear, tempered safety
glass lens is sealed and gasketed to ensure a durable, long lasting seal
against vapor, dust, and moisture. Commonly used fixtures of this type
used in paint spray booths are 4 lamp, 4-foot fixtures with 32, 40, or
60-watt HO lamps, with 40-watt lamps being the most commonly used. The
fixtures will normally have an inside, rear, or dual inside/rear access
hinged door panel for the purpose of servicing the lamps and ballasts.
In fixtures with an inside access, an interlock switch is provided and
is to be wired in such a way as to disable paint spray equipment when
the inside access panel is opened. This enables the fixture to be
mounted in spray booth panels without the previously required second
lens. In instances where a non-hazardous rated fixture is used, these
must be mounted behind a sealed stationary mounted lens. These fixtures
can only be serviced from the outside of the booth.
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Hazardous rated fixtures must, by code, be used in areas that extend
from the edges of any opening of the booth in accordance with the
following:
* If the exhaust ventilation system is interlocked
with the spray application equipment, then the Division 2 location shall
extend 5 feet horizontally and 3 feet vertically from the open face or
open front of the booth.
* If the exhaust ventilation system is
not interlocked with the spray application equipment, then the Division 2
location shall extend 10 feet horizontally and 3 feet vertically from
the open face or open front of the booth. The term interlocked means
that the spray application equipment cannot be operated unless the
exhaust ventilation system is operating and functioning properly and
spray application is automatically stopped if the exhaust ventilation
system fails.
If fluorescent light fixtures are actually mounted
inside a paint spray booth and are not recessed panel mounted, then
Class I, Division 1 explosion proof fixtures must be used. These
fixtures are typically available with 2, 3, or 4 lamps in 2 foot or 4
foot length fixtures. A Class I, Division 1 location is defined as where
hazardous atmosphere may be present during normal operations. It may be
present continuously, intermittently, periodically, or during normal
repair or maintenance operations, or those areas where a breakdown in
processing equipment releases hazardous vapors with the simultaneous
failure of electrical equipment.
When actually selecting light
fixtures for a paint spray booth, it is important to think about what
you want to achieve and to get an even distribution of lighting in the
booth. There are many factors that can influence lighting levels in a
spray booth application. In order to help select the right fixtures, the
following information is important to know:
Booth Information
* Is the application retrofit or new?
* What are the inside dimensions of the booth? (To include width, length, and depth.)
* What is the specific booth design?
* If a retrofit situation, what are the type and number of existing lights in the booth?
* For servicing, do you want the lights to be inside access, outside access, or both?
*
Does the existing booth have a hipped ceiling? If yes, what is the hip
size and degree? Are there lights in the hip, and is it possible to add
lights to the hip?
* Does an existing booth have corner chambers, and what are the sizes?
* What construction is the booth floor?
* What materials are used for booth construction in the floor, walls, and ceiling, and what are the specific colors?
* Are there man-doors in the booth walls? If so, where?
* Are there any windows or translucent panels? If so, where?
* Are the filters located in the floor, ceiling, or booth walls?
Objects
* What types of products are normally painted?
* What are the shapes of the products (square, round, rectangular, etc.)?
* What is the largest object in terms of width, height, and depth?
* What is the smallest object in terms of width, height, and depth?
* What colors are primarily painted?
With
this information, light fixture manufacturers can use computer programs
to help determine the recommended number and placement of the
fixtures.; As a rule of thumb, 100 foot-candles at a 3-foot height has
been a general industry standard. If a different foot-candle level is
desired to be maintained at a different height, this should be
communicated to your lighting supplier. Light intensity measured on a
plane, at a specific location, is referred to as illuminance.
Illuminance is measured in foot-candles, which essentially are lumens
per square foot. Other factors such as reflectance of surrounding
surfaces, fixture efficiency, and lamp lumen output can influence the
type and quantity of needed light fixtures. As mentioned earlier, the
size of a paint booth also can influence the size of the fixtures. In
larger booths, such as truck paint spray booths, 4 lamp, 8-foot length
fixtures featuring 95 or 110-watt HO lamps are sometimes desired. The
type of a booth can also influence the choice of fixtures. Slim light
fixtures that feature a compact design, which are just 2 1/4-in. fixture
depth, allow for mounting in an insulated panel.
The ability to
see colors properly is another aspect of lighting quality. Light sources
vary widely in their ability to accurately reflect true colors of
objects. The color rendering index (CRI) scale is used to compare the
effect of a light source on the color appearance of its surroundings. A
scale of 0 to 100 defines CRI. The higher the color rendering index, the
less color shift or distortion that occurs. As an example, a standard
cool white T12 (1.5' diameter) fluorescent lamp with a Kelvin
temperature of approximately 4100oK has a CRI of 62, which is considered
low. Where quality or color matching is important, a higher CRI rated
lamp will normally be needed. As a general rule of thumb, the higher the
CRI, the lower the efficiency of the lamp. It is important that a
balanced approach be used when considering CRI, lamp lumen output, and
efficiency of the lamp.
For many years, the lighting standard has
been F40T12 fluorescent lamps. These are 40 watt, 1.5' diameter lamps.
Through technological advances, lamps have been developed that consume
less energy, produce better quality and higher levels of light, such as
T8 (1' diameter) lamps. The T5 (5/8' diameter) lamps, which are starting
to be introduced to the U.S. market, show even more promising results
concerning maintained lumen output over the life of the lamp, energy
savings, and they operate more efficiently at higher ambient
temperatures than T8 or T12 lamps.
Once the light fixtures have
been installed in the spray booth, care must be taken to prevent dirt
accumulation and paint over-spray buildup on the fixture lenses. If not
removed on a continual basis, this will degrade the overall lighting
quality in a booth. A simple, effective light fixture lens covering is
cling-on plastic film. This is a 3 mil plastic with a custom acrylic
adhesive in 12" and 18" widths. It is easy and quick to install and
remove. A total re-lamping program should also be considered as lamps
reach the end of their life.
In conclusion, lighting selection in
a paint spray booth should not be taken for granted. Different
applications can require different light properties. To correctly match
the proper lamp, ballast, and fixture combination, you should consult
and work closely with your lighting supplier before making your lighting
selection. One such manufacturer of fluorescent lighting for paint
spray booths and hazardous industrial locations is LDPI Lighting. They
specialize in this area and are an acknowledged industry leader in
providing lighting solutions for paint booths and hazardous industrial
locations.