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.
