BS 5438 Methods of test for Flammability of textile fabrics when subjected to a small igniting flame applied to the face or bottom edge of vertically oriented specimens

1 Scope
This British Standard describes methods of test for flammability of textile fabrics by observing and measuring the limited flame spread and of vertically oriented test specimens when subjected to a small igniting flame applied to the face or bottom edge. Test specimens can be of a single fabric or any combination of materials representative of the product in use, e.g. coated, multi-layered fabrics.

NOTE 1 Wherever practical, trimmings should be tested as part of the fabric assembly on which they are or will be used.
NOTE 2 The titles of the publications referred to in this standard are listed on the inside back cover.

2 Definitions
For the purposes of this British Standard the following definitions apply.

2.1
glowing
combustion of a material in the solid phase without flame but with emission of light from the combustion zone (Extracted from BS ISO 4880.)

2.2
ignition
flaming of the test specimen for a period of 1 s or more after removal of the igniting flame, unless otherwise specified in performance requirements

2.3
flaming debris
material separating from the specimen during the test procedure and falling below the initial lower edge of the specimen and continuing to flame as it
falls

2.4
hole
a break in the fabric at least 2 mm× 2 mm in size caused by melting, glowing or flaming. If the hole is crossed by any material it is described as discontinuous

NOTE This definition applies only to face ignition tests.

2.5
duration of flame
the length of time for which a material continues to flame, under specified test conditions, after the ignition source has been removed (Extracted from BS ISO 4880.)
NOTE 1 Also called afterflame time.
NOTE 2 Flaming debris is not included in this definition.

2.6
afterglow time
the time for which a material continues to glow, under specified test conditions, after cessation of flaming or after removal of the ignition source, ignoring glowing debris (Extracted from BS ISO 4880.)

NOTE Also called duration of afterglow.

2.7
flame application time
the time for which the igniting flame is applied to the test specimen

2.8
minimum ignition time
the minimum flame application time required to cause ignition (2.2) of the test specimen
2.9
flame spread time
the time taken by a flame on a burning material to travel a specified distance under specified test conditions, measured from when the igniting flame is applied
2.10
damaged length
the maximum extent of damaged material measured in a vertical or a horizontal direction, whichever is the greater, on each test specimen
NOTE Methods for measurement of damaged length are given in Appendix A.

2.11
surface flash
rapid spread of flame over the surface of a material without ignition of its basic structure (Extracted from BS ISO 4880. See also BS 4569.)