How Much Heat Can a Firefighter Suit Withstand

Answering “how hot can a firefighter suit get” isn’t as simple as it seems. In general, firefighter uniforms are made of specialized material that can withstand heat and flames for longer than standard materials. But exactly how much heat they can stand will vary greatly depending on the type of firefighter uniform.

And remember, firefighters aren’t working in controlled laboratory conditions. The reality of fighting fires can get messy, and even professionals can struggle to know exactly how much heat firefighter equipment can withstand in a given situation

Let’s zero in on wildland firefighting in particular. Wildland firefighting clothing and wildland firefighter gear have special heat-resisting properties, as well as comfort, durability and mobility requirements.

Firefighter

Understanding the Heat Exposure in Wildland Firefighting

Wildland fires can be intense. Scientific American reports that forest fires can reach 1,472 degrees fahrenheit (800 degrees celsius). That impacts the human body even at a distance, and even when the person is covered in flame-resistant gear.

One simple rule stated that a firefighter must remain a minimum safe distance equivalent to four times the height of the flame. But as the Fire Research and Management Exchange System reported, that standard doesn’t really work – because particularly in wildland environments, gusts of wind can instantly and dramatically shift a fire’s height, intensity, and direction.

Wildland firefighting also must take into account human exhaustion, dehydration, and fatigue. Wildland firefighters are at work for weeks at a time, either actively fighting fires or doing manual fire-prevention work out in the fields and forests. When they’re fighting fires, they’re also carrying heavy gear, sometimes over long distances. (According to the Centers for Disease Control and Prevention, clothing alone can weigh 15 pounds, while the gear can frequently weigh 40-50 pounds). Heat exposure is only one part of the equation when considering a firefighter’s overall health.

Components of Wildland Firefighter Uniforms

Fire professionals have to be able to move freely in their environments and need gear that is approved for their job – for example, fighting a structural fire is a far different experience than fighting forest or grass fires.

What do wildland firefighters wear? Here’s a non-exhaustive list:

  • Wildland fire shirts: also known as brush shirts, these are secured at the collar and the wrists for maximum protection
  • Wildland fire pants: relaxed-fit for full mobility, but allowed to be cinched at the ankles. They often have larger cargo pockets for carrying gear on the job.
  • Wildland overshirt and overpant: typically bright yellow for visibility in forest and grassland settings. These are worn over the wildland fire shirts and pants for additional protection.
  • Wildland firefighter gear: includes gloves, fire shrouds and masks, eye protection, and rigid belts to keep pants and overpants in place.

They also carry items like helmets, chainsaw chaps (protective clothing for operating chainsaws), hearing protection devices, and a small fire shelter – a pup tent they can open up to protect themselves from a passing wall of flame.

Heat Resistance Standards for Firefighter Suits

Although the Occupational Safety and Health Administration (OSHA) officially regulates firefighter safety in the U.S., the National Fire Protection Association (NFPA) is the organization that sets the more commonly used standards for clothing and gear that you see universally used in U.S. firefighting organizations.

Wildland firefighting clothing will typically be certified NFPA 1975 or NFPA 1977.

  • NFPA 1975: Standard on Emergency Services Work Apparel
  • NFPA 1977: Standard on Protective Clothing and Equipment for Wildland Fire Fighting and Urban Interface Fire Fighting

These certifications go in-depth on the makeup of clothing, measuring things like heat and flame resistance, evaporative heat transfer (in other words, how well it lets sweat evaporate off the body), tear resistance, and the strength of its seams, zippers and fasteners.

Materials are tested and re-tested. For example, in NFPA 1977, garments are suspended above flame and then testers measure the char on the fabric. Garments are subjected to 500 degree heat for five minutes to see how much the materials shrink. Testers exert 70 pounds of force on major seams to ensure they don’t break. And that’s just a sample of the tests involved, for just this one standard.

How Wildland Firefighter Clothing Protects Against Heat

As you might expect, Propper wildland fire pants, shirts and other items are not made of off-the-rack cotton or polyester. These uniforms are made of high-tech fibers that are inherently flame-resistant (FR), rather than beginning with standard fibers and trying to coat them with FR material.

Patented fabrics such as Tecasafe, Sigma, Synergy, and Nomex have been developed by industry to resist melting, and maintain their integrity even when exposed to direct flame and high heat.

Take Tecasafe, for example. Tecasafe® Plus 580 fabric is inherently flame-resistant (FR), meaning its capabilities cannot come out in the wash. The fabric also transfers heat and moisture away from the body, enhancing breathability. It’s certified for NFPA 1977, as well as a number of other NFPA certifications

Sigma is another FR fabric. Tested by the U.S. military and now worn by more than 100,000 U.S. troops, Sigma fabric is light, flame-resistant, and transfers heat away from the body. It’s certified for NFPA 1977 and 1975.

Care and Maintenance of Wildland Firefighter Suits

Although flame resistance can’t be washed out of the fibers of these materials, wildland fire pants and shirts can become less effective more quickly if not washed and stored properly.

Wildland firefighter uniforms should be stored dry, in room-temperature areas. They should also be frequently inspected for damage to ensure the garment maintains its integrity out in the field.

Wash heavily soiled gear in industrial washes. Otherwise, a typical home wash in warm water is safe – but you should not wash them with bleach or fabric softener, and do not dry them with dryer sheets.

Always read the manufacturer information on proper care and maintenance.

The Evolution in Wildland Firefighter Tech

Firefighter gear must continuously evolve to help protect the brave men and women who do this grueling work. Learn more about wildland firefighter uniform requirements, and check out Propper’s range of wildland firefighter clothing and wildland fire gear.