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Friday
Mar122010

Insulated Illumination

     In the Hazardous Materials field, there are many choices for personal tools that you will always want with you. All of your favorites will end up in your personal gear bag. The content of this bag evolves with your experience. What you find works best for the way you respond, will end up being what I call “My magic bag of Tricks”. This bag contains the helpful tools that make your response more efficient and your “Hot Zone” time less miserable. The contents range from skintight polar underwear in the winter months, to favorite tools that just make your job much more pleasant. A main staple for hazardous materials work is the flashlight.

     In 1980, your choices were limited compared to today. Generally high quality hand lights were expensive, heavy, not intrinsically safe {bombproof}, and lost a lot of ancillary light creating shadows. This made their use clumsy and minimally functional. In many cases, they worked against you in a hazardous materials environment. The key towards finding a flashlight that works for you is one of “perspective”. Different environments require different lights to maximize your vision; hence, you must evaluate your “perspective” in regards to the work you will be doing. Police work, in attempting to blind a perpetrator to subdue him, is quite different from gathering data from a hazardous label. In a hazardous materials environment, your sight can be limited by the type of container you are inside {such as the back of a transport truck} or the fact that many incidents occur at night when operators become tired. Additionally, many spilled materials vaporize to some extent, so expect to be working in a foggy atmosphere. The type of portable hand light you will want must focus light, last long, be intrinsically safe, and cut through foggy atmospheres. The most beneficial forward stride for hazardous materials responders in the last 5 to 7 years was the applied technology turning hand lights into field operational tools for the responder. The backbone of the hazardous materials flashlight is the LED {Light Emitting Diode}. Three of the above factors depend on your choice between the older bulb type and LED. Since 75% of your evaluation involves this factor, it is useful to understand illumination.

     Originally, all incandescent bulbs consisted of a tungsten filament surrounded by vacuum inside a glass tube. Incandescent literally means, “To give off light as a result of being heated”. The greatest limitation of the incandescent bulb is twofold; 1] the visible output spectrum and 2] Excessive heat generation from the filament. Most of the light generated from the “bulb” falls into the infrared or non-visual end of the light spectrum. In fact, only 10% of consumed electrical energy generated ends up as visual end spectrum light. Because tungsten filaments burn hot, they rapidly decompose leaving tiny particles on the inside of the bulbs vacuum glass. To produce more light tungsten filaments can be operated a few degrees hotter, but this shortens the bulb life dramatically. Longer-life tungsten filaments that are heavier can be used, increase bulb life only, while not increasing useable light.

     The next step forward for the “bulb” was to replace the vacuum with various inert gases. The generic concept with this science was to introduce a halogenated gas that would cause a chemical reaction upon heating by removing the tungsten filament deterioration from the inside of the glass bulb and replacing it back on the filament. This worked causing a longer life to the bulb. The up side was an increased white light that provided more bright light in the visual spectrum. The down side was a hotter bulb that was more subject to breakage when jarred. In addition, quicker battery drain needing frequent replacement was also a problem. These gases increased the average life span of the tungsten filament type “bulb” to the following amounts.

1] Halogen- 2,500 hrs

2] Krypton- 2,000hrs

3] Xenon- 5,000hrs

4] High Pressure Xenon- 5,000hrs {Half size of Xenon due to principal of operation}

These all have various offerings for discharged light and each must be evaluated for the type of work “perspective” you are performing.

     As soon as LED’s became functionally practical, the changes were immediate. The LED is a light bulb with no filament to burn out. Each LED {Light Emitting Diode} is encased in crystalline clear poly-resin making it nearly indestructible. The shear “brightness” or blinding light to the human eye is slightly less than incandescent tungsten “bulbs” but the average LED life span is a staggering 100,000hrs or better. Since it draws very low energy in wattage, battery life is exceptional, and the LED is cool enough to the touch while operating. Finally, the LED has almost no light in the infrared spectrum so all discharged light is visible. This feature makes up for the shear power of the incandescent, as well as its other features. The LED ended the fragility, battery drainage, bulb burnout, heat problems, and total usable light all in one bounce.

     There are many terms for total understanding of light direction such as lumen, candela, lux, emittance, light power flux, luminous intensity, incident flux, and diffuse reflected flux. Many of these pertain to the following appurtenances and should be discussed in a more intensive study. Simply put, candlepower is an obsolete unit of illumination because it deals with the light emitted at the candle {or source} not at what you want to illuminate. Lumens, which is much more useful, measures the output of light towards the object you want illuminated. The older candlepower is equivalent to one lumen per square foot. Since the International System of Measurements uses lumens, you will be able to quantify any hand light purchase throughout the world. One lumen is then, the unit of luminous flux equal to the amount of light given out at a solid angle from a source of one candela intensity that radiates in all directions. This is, the light output at the source of what you want illuminated. Past understanding this concept, it is still subjective in relation to the human eye viewing its light. You must try out the lights together and see if they can improve YOUR work task! Many other physical features can enhance a hand light productiveness in your “perspective”.

     For Hazardous Materials work, hand light size is one. A good light should fit your hand and not have to be dragged in a bucket beside you. It should be of irregular shape or be checkered on the grip as chemical hazards can cause its surface to become slippery. If you cannot smoothly turn it on with one hand, it is no longer a tool but part of your work. Switches should be simple enough for operation with multiple layers of chemical gloves. Insulating illumination refers to the intrinsic gasket around the flashlights battery compartment that prevents activation sparks from reaching the hazardous environment. Intrinsically safe is a must for hazardous materials response as a thrown switch could detonate flammables inside the “Hot Zone”. For customizing, a neck or wrist lanyard can be very useful.

     Construction of hand lights is important for durability. One of the overall finest that I have found are the “Pelican” models. In my links, you can reach their website. Crafted of colored poly materials they are impervious to chemicals and if damaged Pelican will replace at no cost. Personally, I have not been able to break one yet. Reflectors have made many combinations of incandescent and LED combinations more versatile, but again, when considering bulbs and LED together think “perspective”. “Bezels” are the lenses that protect the light producer while allowing the target to be illuminated. Look for durable materials that will not yellow or scratch such as Lexan and Pyrex. If night vision is necessary, the addition of colored filters will be a necessity. If you choose a headlamp, the main benefit here becomes the “hands free” operation. Just be sure it will compliment various hazardous materials CPC {Chemical Protective Clothing}.

     Finally, Batteries need addressing. Rechargeable batteries have operational effectiveness challenges to overcome. Always be sure that your choice has the option to run off both alkaline and re-chargeable batteries. Because rechargeable batteries can fail due to memory problems, forgotten recharging schedules, and untimely drainage, do not rely on them for your only means of power. By planning for the worst and hoping for the best, you will be able to illuminate your “perspective".

                                                                                                                                HazMatMike   

 



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