Basically, this method is the vertical strip test in which the rate of propagation of the flame is measured in terms of the distance in milometers per minute that the base of flame travels up a strip ( 900 mm x 75mm). The time to travel two markers 500 mm apart is observed . The rate of propagation is then given by (500/t x 60 mm/min), where t is in seconds.
some other information’s like after-flame, after-glow, char length are also derived and reported:
1、After-flame : The time in seconds that elapses between the removal of the std. gas lighting flame and the flame extinction.
2、After-glow : the time in seconds between flame extinction and the end of any glowing.
3、The charring : the extent of charring is given by ‘char length. This is the difference in mm between the original specimen length and the undamaged length of the specimen.
Method B :
Fabrics made from thermoplastic fibre’s don’t burn in a convenient manner. They melt, shrink, curl away from the flame. In method B the test specimen is hung in the sheet form and the igniting flame applied at right angles to the sheet and near to the bottom edge. The amount of damage and time taken is observed and reported.
Method C :
This test is concerned with the transmission of flame across pile fabrics.
* The lower speed of propagation of flame over wool, silk, acetate fabrics is due to the fact that they melt and drip during burning.
Flame proofing and Flame resistant finishing
Special chemical finishing processes have been developed which reduce the flammability of the treated fabrics. Some recent developments have led to the introduction of such finishes as Proban, Antiflamm, and Lifeguard. Such finishes should have following properties:
Be permanent and not disappear at the first laundering or cleaning.
Be non-toxic .
Be non-irritant to the skin
Leave the handle and the other desirable properties unaffected.