Intrinsic safety in electronic PPE
The fire service is using electronic PPE more often in firefighting applications and the overall reliance on electronic PPE is increasing
By Mike McKenna
Where does the fire service want to draw the intrinsic safety line between expected and unexpected environments as it related to PPE? This debate is just getting started and continuing on many fronts.
PPE is usually defined as everything that firefighters wear or hang on their bodies. This includes protective clothing, helmets, gloves, boots, self-contained breathing apparatus, PASS, thermal imaging cameras, flashlights, etc.
In the background on the electronics side of the PPE equation is the concept of intrinsic safety. Intrinsic safety means an electronic device cannot ignite in an explosive atmosphere if the device suffers some internal electronic failure capable of causing an ignition.
Intrinsic safety can be a very important feature in the electronic equipment used in the fire service operations such as hazardous materials incident mitigation or drug labs, but what about structural firefighting?
Firefighters can trust that the intrinsically safe electronic PPE that were purchased are not going to cause ignition. At the same time, firefighters are entering the same environments with a $10 flashlight that is attached to the structure helmet with a piece of inner tube. I am thinking about the routine structure fire, the fire service "bread and butter" and wondering what level of intrinsic safety is appropriate.
What is intrinsic safety?
Intrinsic safety requirements were not designed with firefighting in mind and direct correlations are difficult. Intrinsic safety is an approval based on, among other things, the class, division and group for the anticipated environment that the equipment will be subjected to. The class is the type of combustible material that the device will encounter: Class I are combustible vapors in air, Class II are combustible dusts and Class III are combustible fibers.
The division is the probability that the device will be exposed to the three classes. Division 1 means that the device will be routinely exposed to the combustible materials and Division 2 means that the device will be exposed during abnormal conditions. For example, Class I Division 1 would be combustible vapor exposure during a routine operation such as a storage tank at a refinery. Class I Division 2 would be the same exposure in a spill.
The group indicates the severity of the combustibility based on Acetylene, propane, grain dust and others. An alphabetical designator is assigned based on the relationship to the severity of the individual material.
How is intrinsic safety applied?
Intrinsic safety is rooted in the fire triangle concept and is based on igniting a combustible material with heat or a spark. The goal is to protect the user from the unforeseen or from an equipment failure that could create a possible ignition source.
Not all electronic failures result in the creation of an ignition source. Some electronic failures result in the piece of electronic equipment simply stopping working. Intrinsic safety is applied at different levels to many electronic pieces of PPE, but at what cost?
Historically, many NFPA standards have been based on that single catastrophic event. NFPA structural requirements, for example, are rooted in protecting a firefighter in a single flashover event.
High levels of intrinsic safety makes sense in the single catastrophic event context, but many standards are trying more and more to balance the need for a protection in a catastrophic event with the protection required during routine operations.
In many cases those requirements are in direct conflict. Thick and insulating garments, for example, are great for protection during a flashover, but have low ability to release body heat during routine operations. High levels of intrinsic safety are great for hazardous materials incidents such as working a drug lab, but what about the routine free-burning structural fire?
The fire service is using electronic PPE more often in firefighting applications and the overall reliance on electronic PPE is increasing. More firefighters become lost and trapped and have to utilize the PASS fighting structural fires than during specialized incidents.
Intrinsic safety in the real world
Currently, the SCBA has a different intrinsic safety requirement than the PASS and those requirements are different than the thermal imager. I believe that intrinsically safe fire radios are more of an exception than a rule.
On the other hand, we have that pesky flashlight. What is the proper level of intrinsic safety that should be applied to electronic PPE for firefighting? Should it all be the same? Should our flashlights be required to be intrinsically safe?
While I am all about firefighter safety, I wonder if firefighter safety could be enhanced if the intrinsic safety of electronic PPE were lowered from its current level to a level more in line with the hazard. How might lowering the level of protection enhance firefighter safety? Lowering from the higher levels of intrinsic safety reduces some restrictions on the circuitry and electronic components.
I discussed this with a manufacturer and was told that he could "make a PASS that would make your ears bleed." While I am not advocating a PASS that makes our ears bleed, maybe the fire service could benefit in the long run from improved electronic PPE performance and reliability that comes from rethinking the levels of intrinsic safety currently required.
The fire service could benefit from improved electronic options and some of the electronic PPE under development could be enhanced.
Attempts at lowering requirements may be like swimming against the current, but every technical committee that is facing the development of electronic PPE is facing the dilemma and they are researching and looking for input.
This is not a debate about the cost of product development, but of capability limitations and what level of intrinsic safety is appropriate for the fire service.