'Explosion Proof' and 'Intrinsically Safe' are the two most common, well known classes of lighting based on two different ways of preventing explosions in an atmosphere containing hazardous vapor. This includes handheld, portable, and wearable lighting, as well as complete facility lighting systems. The difference between the two classes of lighting is significant, and is based on the premise of Containment vs Prevention.
The Containment (Explosion Proof) method allows the ignition to happen, but keeps it from spreading to an open atmosphere where it becomes dangerous.
The Prevention (Intrinsically Safe) method controls the source of ignition, and never allows for enough energy to make ignition possible.
Bottom Line: The safest, most representative method of prevention is using Intrinsically Safe devices.
Intrinsically Safe (IS) Standard
There are international safety standards that certify light systems as Intrinsically Safe:An Intrinsically Safe rating means that the electronics or wiring contained within the equipment can not spark at all.
Explosion Proof (EP) Standard
Equipment with an explosion-proof classification does not mean that the lighting will survive an explosion (this is a common misconception). It means that the lighting is housed in an enclosure that will prevent an internal spark from causing an external explosion.
There are three recognized classes and two "divisions" of hazardous atmospheres that the lighting fixtures are judged against. The three classes are:
There are two "divisions" of hazardous conditions within each class:
Intrinsically safe lighting is low-powered lighting, often incorporating batteries and rechargeable batteries. This lighting often makes use of low-voltage bulbs, like light emitting diodes (LEDs). Halogen flashlights and high-intensity discharge lights (HID) are often classified this way.
In reality, intrinsically safe lights are based on designs that limit the amount of electrical energy used to non-incendive levels, so that sparks cannot occur at amperages and voltages that can cause explosions in hazardous atmospheres.
A typical fixed industrial IS lighting circuit would incorporate a temperature sensor installed in a way that limits the amount of energy to the light, based on the temperature. The lighting is controlled by ambient temperature, but must still meet high lighting standards.
High-intensity discharge lamps produce light in a transparent, sealed fused quartz tube or fused aluminum tube filled with gas and metal salts. An electric arc, started in the gas, heats and evaporates the metallic salts to form a plasma that intensifies the light caused by the arc itself. These high-intensity lights make light per unit of power more visible than fluorescent or incandescent bulbs. More of the energy produces visible light, rather than infra-red (heat) energy. However, the lights do use up the fuel (metallic crystals) and light levels drop by up to 70 percent over 10,000 hours of use.
Explosion Proof devices are designed to allow ignition to occur, but to contain it so that it does not cause an external explosion.
Intrinsically Safe devices never allow an ignition to happen in the first place.
Intrinsically Safe lighting is widely considered as superior to Explosion Proof lighting for use in hazardous locations. CLICK HERE for a complete listing of BAYCO lighting products available from goSafe. For more information, contact your goSafe representative at sales@gosafe.com