Many questions come up during the search for new turnout gear. Stop here for a few of the most commonly asked ones. If you have a question you would like to see answered here, please contact us.
General
- What is TPP?
- What is Thermal Damage Tolerance?
- What is NOMEX® IIIA? Is it one fibre or a combination of fibers?
- What is NOMEX® with KEVLAR®?
- What are the benefits of NOMEX® filament yarn?
- What is the difference between producer-colored and piece-dyed fabrics?
General
1. What is TPP?
TPP stands for Thermal Protective Performance. The TPP rating of a fabric or composite refers to its
thermal insulation characteristics when protecting the wearer from fire. TPP is measured using a
combination of flame and radiant heat sources with a heat flux of 2 cal/cm2-sec. The flame is impinged on the outer surface of a four-inch by four-inch area of the fabric or composite. The time required to reach the equivalent of a second-degree burn at the calorimeter on the other side of the sample is recorded. This time (in seconds), multiplied by the heat flux of the exposure, gives the TPP rating. The higher the TPP rating, the more protection a fabric or composite provides the wearer.
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2. What is Thermal Damage Tolerance?
Thermal Damage Tolerance is a qualitative measure of the stability of a fabric after flame exposure. After a fabric is exposed to flame, does the material break open, form a hard char or remain flexible? NOMEX® fabrics will form a flexible char when exposed to flame; upon cooling, the char will harden. Fabrics with high levels of KEVLAR® remain flexible after flame exposure.
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3. What is NOMEX® IIIA? Is it one fibre or a combination of fibres?
NOMEX® IIIA is a blend of 93 percent NOMEX®, with 5 percent KEVLAR® added for break-open resistance and 2 percent P140 added for improved antistatic performance.
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4. What is NOMEX® with KEVLAR®?
NOMEX® with KEVLAR® represents the family of outershells that contain blends of high levels of KEVLAR® (50–60%). The higher KEVLAR® content increases the cut resistance and thermal damage tolerance of these fabrics. Examples of these materials in the trade are Advance®, Crusader® and Fusion®.
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5. What are the benefits of NOMEX® filament yarn?
Filament yarns are continuous strands of fibre (as opposed to spun yarns, which are made up of short pieces of crimped fiber that are twisted together). Filament fibers tend to be stronger and have lower friction properties than spun yarns. Filament yarns are used in high-strength outershells and low-friction inner liner fabrics.
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6. What is the difference between producer-colored and piece-dyed fabrics?
Producer-colored fibres are colored during the fiber-making process, while piece-dyed fabrics are colored after the fabric is woven together. Producer-colored fibers generally have better color stability to light and heat exposures. Piece-dyed products tend to come in a wider variety of shades.
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