Explosion Proof LEDs: Advanced Technology for Spray Booth Applications|
One of the most critical aspects of a properly designed spray booth is the type of lighting to be used in its operation. For most applications, the number and size of the lights needed is determined by the size of the booth. The second most important consideration is the quality of the illumination provided by these lights. It is well known that different types of lamps produce light of differing intensity and color ranges, and it is these factors that have direct bearing on the ability to produce consistent quality spray work in the booth.
Most spray booths utilize fluorescent light fixtures that usually fall under Class-1 Division-2 or Class-1 Division-1 ratings and are approved for use in Hazardous locations where volatile gases and flammable liquids are handled or prepared. Fixtures intended for use inside the booth without the protection of panels or integral mounting recesses must be rated Class-1 Division-1 explosion proof while fixtures mounted inside of panels built into the booth with protective seals can be Class-1 Division-2.
Aside from ensuring that you have the properly rated lamps for your intended spray booth application, it is critically important that you select lights that will produce the most effective illumination for close work. Light quality and spectrum, even distribution, and reliability are important considerations and must be taken into account when choosing fixtures for use in the demanding environment of a spray booth. The ability to inspect and assess the quality and uniformity of spray applications is directly affected by the lamps used, and poor lighting can have serious detrimental effects on the quality of the finished products.
The best lighting will provide uniform illumination from all angles, and not create weak spots where light fails to disperse evenly. Good lighting will also render true colors and textures accurately and have a high CRI, or “Color Rendering Index”. This is extremely important in applications that require the finished product have high aesthetic appeal such as automotive painting. This CRI is based on a scale of 0 – 100, with a higher number representing a higher CRI, or ability to render colors accurately. Standard fluorescent bulbs are generally rated at an approximate CRI of 62. Higher ratings tend to require higher output, so efficiency tends to suffer as CRI increases, thus requiring a compromise between high CRI and output efficiency.
Most applications have relied on high performance 40 watt fluorescent bulbs that have improved efficiency and output ratings over plain fluorescents. While effective, they still consume significant amounts of electricity, and tend to have somewhat shorter life spans than standard fluorescents. In addition, their long tube designs are often cumbersome to handle when it is time to relamp with fresh tubes, and the seals and covers often employed in their construction are difficult to replace. It is because of these traits that advances in lighting technology have been rigorously pursued and applied in hazardous location lighting applications, resulting in significant improvements in both light quality and efficiency. One of the most promising areas of technological progress has been in the development of the light emitting diode, or, LED.
Although LEDs have been around for decades, it is only in the last ten years that advancements have allowed them to become competitive with more traditional types of lighting equipment. Modern LEDs now rival their traditional counterparts in lumens per watt, and far surpass the traditional incandescent in both luminosity and efficiency. Their design produces illumination through a process called electroluminescence, where electrical energy is passed through a semi conducting material rather than through a filament. This creates light without the usual high temperatures associated with filament based bulbs, making LEDs an excellent choice for inclusion in hazardous location applications.
In spray booth rated units, LEDs are arranged in rows and fitted within tubes resembling traditional fluorescent fixtures. They are then mounted in similar fixtures and are installed and operated in the same manner as regular fluorescent lamps. The difference however is in the amount of energy used, and the lifespan of the lamps. The highest quality fluorescent lamps produce very good light, but at the expense of higher energy consumption. The longest lived fluorescents are rated at approximately 50,000 hours, but also require special ballast to achieve this rating and are a great deal more expensive than normal fluorescent lamps.
LEDs in contrast have an average lifespan of 50,000+ hours. They require no special ballast, and are highly energy efficient. The Larson Electronics EPL-48-2L-LED Explosion Proof LED light with 4 foot LED bulbs is an excellent example of the advancements in LED technology available for use in modern hazardous location lighting applications. Explosion Proof and rated both Class-1 Division-1 and Class-1 Division-2, this light produces 90 lumens of light per watt. It draws only a 3rd of the electrical energy a normal 60 watt T5HO fluorescent uses, making it significantly less expensive to operate. It is impact resistant, and the Pyrex tubes add reliable protection to an already solid unit. The entire assembly is mounted in the same manner as a traditional fluorescent fixture, but requires less space as there is no ballast attached to the unit, resulting in a slimmer profile and lighter weight.
In standard form, the Larson Electronics EPL-48-2L-LED operates at a color temperature of 4500 k, putting it somewhat higher on the CRI scale than a standard fluorescent fixture. Optional versions can be had that operate at 5600k or 6500k, putting the lamp well within the realm of higher output fluorescent lamps. Relamping is straightforward, and the unit uses screw down caps to secure the lamps within the unit, doing away with the common and less secure tap and knock off method more commonly found in traditional fluorescent spray booth lamps. The need for relamping is also reduced by the unit’s long life expectancy of 50,000+ hours, resulting in a lamp that will operate for years before needing servicing. Considered as a whole, the benefits in efficiency, longevity, and reliability found in the EPL-48-2L-LED demonstrate the improvements in explosion proof lamp technology that LEDs now represent.
While it is critical that properly rated lamps be used in hazardous applications such as spray booths, it is also important that the lights perform to the standards necessary to maintain quality and productivity. LEDs are now more than capable of performing to these standards, and represent the next step in the evolution of explosion proof lighting technology.