ELKTON, Md. — When you're slopping around and fishing hose out of calf-deep water on the fireground and your feet and hands stay dry, there's a reason for that. Tucked between the outer and inner layers of firefighting PPE is a barrier that keeps out water, chemicals and bodily fluid.
There's a lot to be said for that on a cold day. Comfort is king.
And anyone who's found himself soaking wet before the first bale is cracked understands the challenge of getting turnout gear to breathe and wick body moisture away. That too is important on a cold day.
It is a much more difficult task to move the sweat your body generates away from you than it is to keep outside moisture at bay. Getting the optimal mix of protection and breathability in PPE is a hard-fought battle and one that is by no means over.
It's with the hope of winning that battle in mind that W.L. Gore opened its multi-million dollar testing facilities, part of which is dedicated to understanding how firefighting PPE stands up to varying stresses.
For example, Gore subjects firefighting boots with its liner material to an in-water test of 500,000 repetitive flexes that simulate steps.
Gore is best known in the civilian world for its Gore-Tex barriers. The barrier in firefighting PPE is known as Crosstech, which is Gore-Tex with added protection against bodily fluids and liquids found in vehicles.
The centerpiece of its new test facility is a biophysics lab with a chamber about the size of a two-car garage that can mimic nearly all outdoor conditions to test PPE performance.
Embedded in the arched ceiling are a series of lights that replicate different sun intensities at different times of the day. The lighting produces the full solar radiation spectrum minus ultraviolet rays, as those would put the human test subjects and researchers at risk.
The chamber also can produce ambient temperatures from -58 to 112 F, relative humidity from 5 to 98 percent and wind speed from 1 to 22 mph.
This is the only chamber of its kind, says Matthew Decker, Gore's comfort and biophysics core group leader. "Comfort is the absence of discomfort," he says.
And this elaborate chamber is set up to measure just that — comfort. In it, local firefighters, college students and Gore employees don full turnout gear work on treadmills and a ladder and roof prop. There, the subjects are monitored for body core and skin temperatures, sweat and shiver rates, and peripheral blood flow.
They are also asked how they feel. Comfort, Decker says, is subjective, a perception that occurs in the brain. Things like how a material feels on the skin plays a role the perception of comfort, he says.
Perception and psychology are two of the four key research areas Gore is exploring as it develops and evaluates materials; physiology and physics are the other two.
The lab also features a rain tower where garments are subjected to anything from a misting to a pummeling. The rain droplet size and distribution has been engineered to match what occurs in nature, with the sprinkler head set at 24.7 feet high so the drops can reach terminal velocity.
Luckily for Gore employees and local firefighters, only mannequins are used for rain testing. Those mannequins can be hit with rain and air temperatures between 41 and 77 F and at wind speeds between 0.4 to 5 meters per second, a maximum of almost 16.5 mph.
Fire and heat
Another section of Gore's research center houses a heat and flame protection science laboratory. In it, they test PPE material for flame resistance, thermal insulation and thermal stability.
Gore tests either complete turnout gear clothing or swaths of it, depending on the test, to learn the amount of heat that transfers through material, how hot it gets and how long it stays hot, says Shawn Riley, Gore's heat and flame protection core group leader.
The stored thermal energy test, how long turnout gear stays hot, measures the amount of time it takes for skin to receive a second-degree burn after the heat source is removed.
That's important because firefighters have been experiencing burn where the reflective material is on their turnout gear.
They discovered that moist air was being trapped beneath the reflective material due to a lack of air movement, which led to the burns, said Bill Gorak, a heat and flame production scientist for Gore. This discovery helped Gore develop its lightweight Parallon barrier that it introduced last year.
Firefighters don't want to have to think about if they'll stay dry on a burner or if the sweat trapped in their bunkers will lead to a steam burns. But it's nice to know someone is thinking about it.