What You Need to Know: ASTM F2733 – FR Rainwear Standard for Flame Hazards

November 7, 2013

Fall is a time of year when weather conditions can vary widely – from sun to rain to snow depending on your location. Rainwear is FR protection that is frequently overlooked but can be a much desired item of clothing by your workers as colder temperatures and wet weather roll in.

ASTM F2733 is the specification that establishes test methods, minimum physical and thermal performance criteria, a suggested sizing guide and suggested purchasing information for rainwear for use by workers who are potentially exposed to industrial hydrocarbon fires or other petrochemical fire hazards. The intent of this standard is to outfit workers with products that will lower the percentage of body burn and burn severity from a 3 second flash fire, thereby increasing survivability.

The National Fire Protection Association defines flash fire as, “A fire that spreads rapidly through a diffuse fuel, such as dust, gas or vapors of an ignitable liquid, without production of damaging pressure.” Flash fires are characterized by high temperature, short duration and a rapidly moving flame front.

In fact, NFPA 2112 is often seen as the parallel, or complementary, standard to ASTM F2733 as both set forth minimum requirements to maximize protection for workers facing flash fire hazards. NFPA 2112 is for work shirts, pants and coveralls while ASTM F2733 is specific to rainwear.

Performance requirements of ASTM F2733

Some of the performance requirements of ASTM F2733 are outlined below:

Flame Resistance – Rainwear material shall be flame resistant and shall not melt or drip when tested in accordance with ASTM D6413 and shall exhibit no more than a 2 second after-flame time and less than 6” char length.
Thermal Protection – Rainwear material shall be tested in accordance with ASTM F1930, a design test, after one washing and one drying.
Flash Fire Protection – total body burn must be less than 40%.
Leak Resistance – Material must withstand water pressure of 30 psig without leaking. The seams of the rainwear must not exhibit any evidence of leakage when exposed to water at 3 psig for 2 minutes.
Tear Resistance – Material shall have a trapezoidal tear resistance of 6 pounds in the warp direction and 6 pounds in the fill direction.
Moisture Vapor Transmission – If the rainwear is marketed as being breathable, it must be tested.
Markings and Reflective Materials – These materials attached to the rainwear shall be permanent and shall not degrade the performance of the rainwear.
Rainwear Construction – Utilize materials, stitchings, tapes, coatings, fasteners, and closure materials that minimize heat conduction for the construction of compliant FR rainwear. Fasteners and closures used, for example, zippers, snaps and buttons that are made from metal shall be covered with a layer of rainwear material on the inside of the garment such that these items of construction will not contact undergarments or skin (1).