Time to ditch the compromise?
Published: 24 June, 2015
WL Gore launches a membrane solution that it believes does away with the compromise between thermal protection and comfort.
The Parallon System comprises not one waterproof/breathable membrane but two newly-developed Gore membranes ‘sandwiched’ around a thermal barrier. By keeping the thermal layer dry, Gore believes that the Parallon System will prevent steam burns that can occur in sub-flashover conditions when wearing wet gear. It will also prevent wet compression burns that can occur when a firefighter bends down or kneels when wearing hot and wet gear.
Speaking to Hemming Fire, Denise Tracey, Product Specialist at Gore explained that the Parallon is the result of market research that indicated that although firefighters liked the Gore membranes’ level of protection they nevertheless felt comfort could be better: ‘Not so much in a structural fire situation but certainly when working outside the fire ground or at an incident you may become more aware that you are wearing a level of protection that is higher than what is required for that situation. And then you can feel hot and sweaty,’ she explained.
In the past, fire services have had to chose between fire kit with a membrane between the outer layer (eg the Nomex/PBI fabric) and the thermal layer, or fire kit where the membrane is between the thermal layer and the next-to-skin layer. Putting the membrane next to the outer layer results in decreased breathability but increased protection (by keeping the thermal layer dry). Putting the membrane close to the skin provides greater breathability, but risks the thermal layer getting wet from the outside, thereby increasing the transmission of heat.
The high breathability of the Parallon ‘sandwich’ is ensured by some clever garment construction. While the inner membrane is completely seam sealed so that the wearer is protected from outside moisture, the outer membrane is only seam sealed at key places such as the shoulders. In Denise Tracey’s words, this creates a ‘funnel’ effect with the widest point on the outside membrane enabling the moisture vapour to quickly dissipate outside: ‘So as soon as the moisture has evaporated through the first membrane, it goes straight out.’
According to Gore, one of the benefits of the new system is consistent thermal protection. Its research has indicated that when tested for an indicated time to second-degree burn in an ordinary fire ground heat exposure (i.e., 0.2 cal/cm2sec), wet conventional gear loses 34 percent of its thermal protection compared to when it was dry. This is because water transmits heat quicker than air. However, its research highlights that the Parallon liner system loses only 4 percent of its thermal protection, remaining relatively unchanged after becoming wet. To prove that this does indeed make a noticeable difference, Gore has developed an ‘oven glove’ demonstration where users can feel the difference for themselves. By holding their hands over streams of hot air, one encased in a wet Parallon fabric ‘oven glove’ and the other in normal glove featuring a membrane next to skin (i.e. with the thermal layer wet), users can verify the difference for themselves.
Interestingly, in order to comply with NFPA standards the Parallon will come in a slightly different version for the North American market. NFPA 1971 specifies that the outer shell be removable from the moisture barrier and thermal barrier sewn together, so an additional layer has been added to the Parallon to protect the outer membrane. ‘But the system works exactly the same, as the thermal barrier is protected,’ clarified Denise.
An additional important benefit of the Parallon is that by keeping the thermal barrier dry the drying time of the full fire kit ensemble can be reduced drastically from around five hours to only two hours.
Although Parallon is not commercially available yet, availability is expected late summer or early autumn.