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DuPont Personal Protection

Technical Data

Glossary: Nomex®

This glossary contains definitions for some of the most common technical terms relating to thermal protection and protective apparel.



Thermal Characteristics
Arc Thermal Performance (ATPV): A reported value from electric arc testing. Basically, it is the measure of how much heat can be exposed to a flame resistant garment before a second degree burn injury is expected to occur.
Electric arc: The passage of substantial electric current through ionized air.
Flame resistant: The characteristic of a fabric to resist ignition and to self extinguish if ignited.
Flame retardant: A chemical substance used to impart flame resistance - not part of the basic fibers chemistry. Flame retardant treatments can diminish overtime or with use.
Flammability (Vertical Flame Test): Measures char damage length, afterflame and afterglow time on a 3" x 12" fabric sample exposed to flame at its lower edge for 12 seconds.
Flash-fire: A sudden, unexpected and intense fire caused by ignition of flammable solids, liquids, gases or dusts.
Inherently Flame Resistant: The flame resistance properites are a result of the chemistry of the material (fiber). Flame resistance will not diminish over time or with use.
Limiting Oxygen Index (LOI): Determines minimum oxygen content (%) in air that will sustain combustion of a material.
Mannequin Test for Predicted Body Burn Injury: Predicts second- and third-degree burn injury for garments on an instrumented mannequin in a controlled flash-fire exposure.
Stoll Curve: A plot of thermal energy and time used to predict the onset of pain sensation and a second degree burn, in human tissue
Thermal Conductivity: Rate at which heat will flow through a material.
Thermal Protection: The resistance to flame and associated thermal transfer through the garment.
Thermal Protective Performance (TPP): A fabric specimen is exposed with a combination of radiant and convective energy. The total energy required to cause second-degree burn injury to human tissue is determined based on heat transfer through the fabric specimen and the Stoll second-degree burn criteria. Single and multiple layer fabric specimens can be tested.
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Standard-Setting Organizations
American Society of Testing of Materials (ASTM) ASTM publishes both performance specifications and test methods for evaluating protective clothing and equipment.
Canadian Government Standards Board (CGSB) CGSB is a voluntary compliance organization that is sponsored by the Canadian government.
National Fire Protection Association (NFPA) NFPA writes voluntary compliance standards related to the Fire Service and other industries.
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Fabric Physical Properties
Air permeability: Measure of air flow through a fabric.
Anti-static Performance: Measures attraction and dissipation of electric charge on fabric
Basis Weight: Weight of fabric per unit area, usually oz/yd2
Bending Stiffness: Force required to bend fabric.
Breaking Load: Load required to break (pull apart) fabric
Bursting Strength (Mullen Burst): Force required to rupture a knit fabric with an expandable diaphram.
Denier (Yarn): Weight in grams of 9000 meters of yarn.
Denier Per Filament: Weight in grams of 9000 meters of a single filament.
Light-fastness: Measures change in knit or woven fabric color after exposure to light from a xenon arc.
Staple cut length: Length of uncrimped staple fibers.
Surface Appearance: Evaluates knit or woven fabric smoothness after repeated home launderings.
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Electricity Definitions
Alternating Current (AC): Current flows back and forth (a cycle) through a conductor. In each cycle, the electrons flow first in one direction, then the other.
Direct Current (DC): current flows in only one direction
Electricity: the flow of an atoms electrons through a conductor
Ground: A conducting connection – which may or may not be intentional – between an electrical circuit or equipment and the earth, can be via some conducting body that leads to the earth
Hertz (Hz): number of cycles per second
Ohm's Law: Current = Voltage/Resistance
Resistance: Anything that impedes the flow of electrons through a conductor and is measured in ohms
Voltage: The force that causes electricity to flow through a conductor and is measured in volts.
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Learn more about the above Standard-setting organizations or the Apparel specifications established by these organizations.