PPE in flashover simulators and burn buildings
Clothing subjected to emergency responses can encounter a wide range of thermal and physical exposures
By Jeffrey O. and Grace G. Stull
Unfortunately, we are often called on to examine firefighter protective clothing equipment that has been involved in incidents where firefighters have been burned or injured.
The purposes of these investigations are sometimes to determine if the clothing and equipment performed adequately and if there were any problems in how it was worn.
Clothing subjected to emergency responses can encounter a wide range of thermal and physical exposures. Moreover, the clothing itself can be found in a variety of use conditions (soiled, contaminated, or damaged) which affects its protective performance.
Some firefighters end up finding themselves in situations where they expect the clothing to work well but they still get burned, while others find the conditions to escalate and just become overwhelmed.
Most departments conduct regular training to simulate fireground exposures, particularly involving the onset of a flashover and similar extreme events, which allow firefighters to identify the telltale signs of impending harm and understand the limitations of their personal protective equipment.
Yet all too often, firefighters get burned during training incidents. In this article, we respond to some inquiries about understanding PPE use in live training fires.
Some of the more common ways for fire departments to simulate fireground conditions and conduct live fire training are to use burn buildings, where controlled fires are set and monitored and firefighters are run through in groups to practice survey and extinguishing techniques.
In many cases, fire departments have their own burn buildings as part of a training academy. In other cases, carefully selected houses and other structures that are ready to be demolished are used for training purposes.
In all cases, the key aspect of this training is close supervision and monitoring of trainee conditions. NFPA 1403 Standard on Live Fire Training Evolutions provides specific criteria for conducting this type of training.
There are also departments that purchase or build special flash fire simulation chambers, the most common of which is the simulator designed by the Swedish National Survival Board in the mid 1980s.
These simulators consist of large shipping containers that include a burn module (10 ft long x 8 ft wide x 8 ft high) and a larger observation module (20 ft long x 8 ft wide x 8 ft high), all equipped with multiple doors.
Particle board is used as the sides and ceiling inside the burn module, and a small crib fire is ignited with a portable propane torch. The fire is controlled via a roof vent and hand line. The goals of the flashfire simulator are to teach firefighters to recognize the warning signs of a flashover and realize the limits of the PPE.
Proponents of this type of training emphasize that firefighter survivability is significantly increased when firefighters can experience fireground conditions under controlled conditions.
However, some complaints have been made about improper live training, which can result in firefighters having damaged gear or, worse, becoming injured as a result of their exposures in simulator or other staged fire.
In some cases, the instructors may be more likely to get burned compared to their students because instructors often spend much more time inside the burn structure rotating students in and out. Consequently, they are exposed to larger amounts of heat energy over longer periods of time. Situations also occur where firefighters simply go too deep into the fire or stay too long.
While close supervision of the live fire training is the key to preventing any PPE damage or injuries, each firefighter involved also has to have a clear understanding of their clothing and equipment limitations and be able to observe, where possible, signs that their continued exposure is hazardous.
While some manufacturers have attempted to develop different types of "smart" sensors that are capable of alerting firefighters that their additional exposure time will result in a burn, this technology simply is not yet available.
Instead, the fire service has to rely on adequate training and to recognize hazardous situations through their ordinary senses. Clearly, firefighters become hot inside the burn structure.
For the most part, they are already hot just by the encapsulating nature of their ensemble, yet one of the key aspects for avoiding injury is paying attention to how quickly you are becoming heated and where on your body you feel hot.
Closest to fire
If a firefighter is inside a burn structure and oriented towards the fire, those portions of his or her body that are closest to the fire or the principal sources of heat will normally become hotter sooner. These tend to be forward and top portions of the firefighter.
Differences in the protective clothing and how the clothing rests against the body will further contribute to which parts of the body heat soonest. These areas generally include shoulders, knees, and elbows that are forward towards the fire when crouching low, and where the clothing is compressed against the body by nature of weight (from the SCBA) or bending of the body. However, knees and shoulders generally have more insulation so the "hot" spots might be elsewhere.
For example, in holding a hose nozzle, the backs of the gloves can become taut against the back of the hand. This feature is important to recognize because part of the insulation provided to the firefighter is from the air layer between the clothing and their skin.
Positions and orientations of the firefighter's body that reduce that air layer also lower insulation. Certainly, if the firefighter holds a particular position for a prolonged period of time, then the amount of heat penetrating the forward, compressed parts of the clothing will be greater.
This is why it is important to keep moving, change orientation, and stay aware of feeling heat through the clothing. Your sensation of pain is a warning that burn injury is imminent. Therefore, in live fire training, it is essential for firefighters to recognize feelings of pain due to heat and to do something about it when possible, so they can take this experience to actual fires.
There may also be indications on the protective clothing and/or equipment when firefighters have put themselves in severe exposures. These signs frequently occur in live training when firefighters exceed the capability of their PPE.
All parts tested
Though all parts of the personal protective ensemble are tested for flame and heat resistance as well as insulation, some components show heat damage much sooner than others. For example, the reflective markings on helmets will lose color and char relatively quickly. Similarly, trim on garments can be one of the first components to show heat damage.
An extremely hot fire will cause crazing and melting for some types of helmet faceshields. Scorch marks or charring of clothing shell materials can further indicate that the firefighter has had an extreme exposure. Nevertheless, it is nearly impossible to detect these changes during the fire.
Therefore, if fire departments note when these kinds of damage occur during live fire training (hopefully with the absence of injury), then they can use these observations to adjust their fireground exposures and link these observations with the types of personal sensations and experienced conditions to understand the circumstances under which the clothing protective capabilities are exceeded.
Another aspect for preventing injury warranting attention is to clearly wear the clothing and equipment in accordance with the manufacturer's instructions. In examining gear from incidents involving burns, we all too often find that firefighters have not extended the collars of their turnout coats or properly deployed the ear covers of their helmets.
Usually, these discrepancies are caught by supervisors in training fires because the expectation is that the firefighters in training will be exposed to fire. Yet, lax behavior on the fireground can lead to unnecessary injuries, and should be an emphasis in live fire training that demonstrates how radically conditions can change.
When properly conducted, live fire training can help firefighters develop a more keen awareness for hazardous situations and when their clothing will no longer provide adequate protection.
This training must be carefully supervised and involve the teaching of not only recognition skills, but sharpen perceptions of heat effects on the clothing and body that act as warning signs for potential danger.
Such training should reinforce that in order to maximize the highest level of safety for the firefighter in the unpredictable environments encountered in everyday emergencies, protective clothing and equipment must be worn correctly and its limitations realized and understood.