The fabric flammability Testing is performed at two stages: the original fabric and the fabric after dry-cleaning and washing. The final classification is the lowest time of the two stages of testing.The requirements are different for plain surface and raised surface fabrics.
Fabrics are classified into Class 1 Normal Flammability, Class 2 Intermediate Flammability and Class 3 Rapid and Intense Burning, according to the time of the burn and the characteristics of the burn. Class 1 is the best class and Class 3 the worst. Fabrics or garments made from fabrics with a Class 3 testing result are not allowed to be sold on the US market.
Plain surface fabrics with a burn time of 3.5 seconds or more are classified as Class 1. Fabrics with burn time less than 3.5 seconds are classified as Class 3 and fail the flammability test. Class 2 Intermediate Flammability does not apply to plain surface fabrics.
For raised surface fabrics, Class 1 fabrics have a burn time of more than 7 seconds. A combination of burn times between 4 and 7 seconds, and burning characteristics that indicate the base of the fabric has been burned through, would result in a fabric being rated as a Class 2 fabric. Class 2 fabrics, or garments made with class 2 fabrics, are considered to have intermediate flammability, but they are still legal to sell in the US market. A combination of burn times less than 4 seconds and burning characteristics that indicate the base of the fabric has been burned through would result in a fabric being rated as a Class 3 fabric. Class 3 fabrics are not legal to sell in the US.
What actions would a person take if his/her coat was on fire? Most people will quickly remove the coat, or extinguish the flame to avoid injury. This is the principle behind the evaluation of flammability for general wearing apparel. The flammability classification does not mean that the fabric will not burn, but that it will not burn so rapidly that grave injury or death might occur. Raised surface fabrics are more risky than plain surface fabrics. The pile on the fabric surface traps more air or oxygen which is essential to support burning.