What does your Structural Firefighting Gear Protect you Against?
To get the best protection out of your Personal Protective Clothing (PPC), you must first know a little about your chosen PPC and its associated Personal Protective Equipment (PPE) and how that is compatible with your fire services resources and training levels as well as your attack strategies and tactics. In this article we will just focus on the protection offered by your Structural Firefighting Ensemble and in particular the PPC element of that protection.
Structural Firefighting for the purpose of PPC, covers all structures, fixed and mobile and includes those “structures” that are “man-made” such as bridges, transportation vehicles and vessels as well as buildings to name just a few. Each discipline of PPE/PPC deserves its own discussion, as the risks across Wildland Firefighting, Haz-Mat and Rescue incidents are varied along with the dynamics of the attack strategies and tactics and often duration and competing priorities of the emergency incident.
In a previous article I spoke of ensembles, being the total body protection and what might be the weakest link in that protective chain.
When you receive your new Structural Firefighting PPC, what is your expectation of its performance and what it protects you against. What is your understanding of what it is made up of and how it will provide the level of protection that you expect? What components provide what protection from what hazards and how do they do that? How does your inspection, cleaning and maintenance program ensure that these components remain “Fit for Purpose” throughout the life of the garment? Some manufacturers even provide a DVD to assist the end-user understand the value and purpose of the components and how to optimize your protection when using their product. While there is an extraordinary amount of science that goes into achieving the perfect balance, it is important to have a basic knowledge of these issues, especially when completing your regular visual inspection and static water penetration test of the moisture barrier in your PPC.
How will your station uniform complement your protection and provide a safe balance during the firefighting activity?
The best place to start in this discussion is with the risk assessment of potential exposure hazards of structural firefighting and how that relates to achieving a physiological balance for the protection of the firefighter.
Just some of the adverse exposure hazards may be;
- Flame impingement,
- Radiant heat,
- Blood Bourne Pathogens,
- Particulate matter.
For most of the structural firefighting PPC on the market, these are some of the hazards that can be protected against, depending on the components and quality of those components that may be present in your PPC.
In addition to these, there often exists a potential blast and fragment hazard at many structural fires.
Depending on your fire services risk assessment prior to purchase, there is also the possibility to provide some protection from some CBRN Terrorism Agents by complying with the appropriate section of the NFPA Standard 1971 -2013.
When considering the list of hazards above, a combination of components provides the critical balance between protection and meta-bolic heat release for the firefighter. The basic components are often as follows;
- Outer Shell
- Moisture Barrier
- Thermal Barrier
- Inner Liner
Historically these may have been in 4 or more layers and rather bulky. But over the last decade or more, some of these layers are being produced in very light weight materials and combined into only 3 or 2 layers.
The outer shell had protected the “engine room” components of the Moisture Barrier and Thermal Barrier, while the Moisture Barrier protected the Thermal Barrier and therefore the firefighter. While the actual science is far more comprehensive than that, when firefighters are inspecting their turnout gear, it is important to assess these components. There are 4 main benefits of having a removable liner in turn out gear. The ability to easily do that inspection is just one of the advantages of having a removable inner. The primary advantage is the ability to wash the outer shell with the majority of the contaminates on it, separately, so as not to “cross contaminate” by potentially forcing these fireground contaminates into the Moisture/Thermal Barriers.
In terms of repairs and replacements, it is far more cost effective to replace only part of the PPC rather than discard the whole garment. Additionally access to certain areas of the garment will be far easier when performing repairs, therefore a reduction in time and therefore cost. All 4 parts of the garment should be chipped so as to ensure the correct components are reassembled and well aligned when returned to the correct firefighter. This also provides a valuable tracking of the history of the garments and assists in the on going “fit for purpose” assessment.
An important element of safety control for structural firefighting, is the ability to ensure that a firefighter does not remove the inner of the PPC. This can be done by designing the collar as part of the inner, and the overpant’s suspenders being attached to the inner on one side and the outer on the other.
An option or additional feature is having very brightly coloured warning tabs clearly displayed if the inner has been removed.
While the outer shell provides some thermal protection, it also provides some abrasion and tear resistance. Related to the issues of abrasion and tear strength is extended UV exposure. Just like buying a fiberglass boat and leaving it sit out in the sun for years, it will eventually deteriorate. So to for most materials, including natural materials and the inherently fire resistant aramids and para-aramids. Thankfully the old practice of hanging turnout gear along the wall of the fire station is rapidly disappearing for a number of reasons. Apart from filling the gear up with all the diesel emissions which were being forced into the material, the first dozen and the last dozen sets in the row were often exposed to either the morning or afternoon sun. As I travel around the world I still occasionally see turnout gear in the front window of the fire truck, receiving the same UV exposure. The very simple answer to caring for your protective clothing no matter what sort of outer shell you currently have, is to store it out of the UV light, preferably in a separate, dedicated well ventilated room with the correct lighting.
I often get asked about colours of outer shell material in terms of visibility. Visibility is important and when new and still clean and the correct dye shade, lime/yellow may be a slight preference. However if these elements are not guaranteed for very long into the life of a structural firefighting garment, of paramount importance is protective performance of the shell material, and the issue of “post burn strength and flexibility”.
Therefore the requirement of the outer shell to simply be a “light colour” so that the end user can see when it is dirty and have it laundered, is the starting criteria. Day and night visibility will still be achieved by florescent and retro-reflective trim respectfully.
The trim needs to be part of the regular inspection regime to ensure that it remains fit for purpose. Often some of the fireground contaminates degrade the performance of the trim even after laundering. At the station the firefighter can simply check the retro-reflective component by simply directing a torchlight held adjacent to your eyes and at right angles to the trim, onto the retro-reflective component of the trim, and see if the light is fully reflected back.
It is important to also provide some “post burn strength and flexibility” in the outer shell material, to afford the firefighter time to survive an accidental higher thermal energy exposure without the outer shell becoming brittle and/or falling off the garment. This is critical during and immediately after an exposure while trying to escape to fresh air or a safe zone.
The moisture barrier is often an unseen component of the structural ensemble, but is a critical component of the firefighters protection. Many firefighters are of the opinion that it is only there to repel water. In fact the moisture barrier plays a critical part in the whole concept of protection from all 6 of the hazards listed above. The very balance between protection and meta-bolic heat release is greatly influenced by the moisture barrier, hence the need to purchase the best possible that is commensurate with your risk assessment and therefore performance requirements. We often hear the comment about the “breathability” of a structural firefighting kit, which infers the passage of air. However this science is about the management of moisture, and the barriers ability to control water droplets from getting in while allowing water vapor to get out.
The moisture barrier plays a role in the thermal protection performance buy preventing water from getting into the air space in the thermal barrier. As we saw in a previous article, if water replaces the air in the thermal barrier it can transmit heat 21 times faster than air. This reduces the effectiveness of the thermal barrier and can quickly become dangerous for the cognitive function of the firefighter as well as increasing the thermal load on the physical function of the firefighter.
While water inside your turnout gear is uncomfortable and weighs a kilogram per litre, it can also be the carrier of chemicals. To protect against this is critical. By applying some ensemble thinking, this is just as critical for the boots and gloves as well.
If blood bourn pathogens are a risk during structural firefighting and rescues, then the correct moisture barrier is also critical.
It is not uncommon to handle bleeding patients at many transportation incidents and some structural fires and rescues. Hence a good understanding of what your PPC is designed to protect you against is important.
Today we are able to achieve the balance between protection from all these hazards and still have good meta-bolic heat release. This is apparent in the test data weather you measure it in Resistance to Evaporative Transfer
(RET) which shows good performance with a lower figure, or Total Heat Loss (THL) which shows good performance with higher figures.
In recent times the thermal protection was achieved by capturing air in reproduced wadding material. Sometimes the more you washed it the more it would fluff up and provide slightly increased thermal protection. This was often bulky and thick and heavy. For the past decade or so, this component is extremely light weight and thin and in some cases alternate designs in association with the moisture barrier, form air layers between the components as well as in the thermal barrier material.
This is the innermost material and is worn against the skin or station uniform or undergarments. It is designed to wick moisture away and is often made from filament yarn and serves towards ensuring that the entire system carries less water and dries more rapidly than any other traditionally oriented concept. They have a higher lubricity, which allows the garment to be a little slippery on the skin and not be pulling against the firefighters movement when wet. It also assists in the donning and doffing. These high-tech firefighter turnout liners helps to deliver high THL values and reduce the risk of water-related burn injuries.
In a previous article we touched on the importance of compatibility of PPC. This compatibility can be challenged where agencies might issue new turnout gear on an “as needs” basis with slight variations in components, hence potentially altering the performance of the PPC. Issues of non-compatibility also potentially exist when different agencies work together with different performing components in turnout gear or even within a fire service on the same fireground.
While there is so much more to elaborate on regarding the science in each of these areas and across issues of quality, design, technology and the associated impacts on each of their performance, firefighters will be better equipped to conduct dynamic risk assessments when armed with the content of even this basic knowledge.
Until next time –Stay safe so you may enjoy a long and healthy retirement.
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