The Exchange Test Method

A-20: Standard for Flammability of Clothing Textiles, 16 CFR 1610 - 45 Degree

Issue Date: 30 Apr 1993

Revision Date: 08/20/2004

1. PURPOSE:

   This standard is designed to reduce the danger of injury and loss off life by providing on a national basis, standard methods of testing and rating the flammability of textiles and textile products for clothing use, thereby discouraging the use of any dangerously flammable clothing textiles.
   

2. PRINCIPLE:

   Specimens are mounted on specimen holders and placed in a test chamber and subjected to flame to determine the burn rate of the fabric. Specimens are classified in accordance with three classes of flammability specified in Sec. 1610.3. 16 CFR 1610 regulation requires that a piece of fabric, which is placed in a holder at a 45 degree angle and exposed to flame for 1 second, should not ignite and spread flame up the length of the sample in less than 3.5 seconds for smooth fabric and 4.0 for napped fabrics.
   

3. REFERENCE:

   16 CFR Part 1610, Standard for Flammability of Clothing Textiles.
   

4. APPARATUS:

   • 4.1 Flammability tester consisting of a draft-proof ventilated chamber enclosing a standardized ignition medium, sample rack, and automatic timing device - see 7.1.
   • 4.2 Fuel Supply - Butane Container No. 4 cylinder of c.p. butane - see 7.2.
   • 4.3 Specimen Holders
   • 4.4 Brushing Device
   • 4.5 Desiccator
     

5. PROCEDURE:

   • 5.1 Cut 5 specimens each measuring 2 x 6 in. (Samples may be cut from east to west or north to south or whichever orientation would present the most serious method of flammability.)
   • 5.2 For plain surface fabrics, the long dimension shall be that in which they burn most rapidly.
   • 5.3 For fabrics with raised-fiber surfaces, the direction of the lay of the surface fibers shall be parallel with the long dimension of the specimens. For textiles with varying depths of pile, tufting, etc., the specimens are taken from that part and test on that surface which has the fastest rate of burning.
   • 5.4 If the specimens do not ignite or are very slow burning in the preliminary test or should have a flame retardant finish, a sample is subjected to the dry cleaning and washing procedures. Specimens are taken from the refurbished swatches.
   • 5.5 Specimen dimensions are marked on the backside and in the direction in which the fabric burns most rapidly by a staple affixed to it.
   • 5.6 Fabrics with raised fiber surfaces must be brushed. Put specimen in place on the brushing device carriage, raise the brush, push the carriage to the rear, lower the brush to the face of the specimen. Draw the carrier forward once against the lay of the raised-fiber surface. Plain surface fabrics do not require this treatment.
   • 5.7 Clamp specimens individually in the specimen holders.
   • 5.8 Dry specimens mounted in holders in a horizontal position in an oven for 30 minutes at 221° F/105° C.
   • 5.9 Place specimens over anhydrous calcium chloride in a desiccator until cool, but not for less than 15 minutes.
   • 5.10. Adjust flammability tester rack so that the finger just touches an unofficial specimen. This step is to insure that the tip of the burner is exactly 5/16 in. from the fabric when test is conducted.
   • 5.11. Adjust flame length to exactly 5/8" long.
   • 5.12. Remove mounted specimen from desiccator and place it in position on the rack in the chamber.
   • 5.13. Place stop cord and weight in proper position to test.
   • 5.14 Push button to run test. The flame is automatically brought into ignition position and held for exactly 1.0 seconds before it retracts back in to the ready position. The time starts at the time the button is pushed. The timer turns itself off when the stop cord burns and the weight drops.
     

6. EVALUATION AND REPORTING:

   • 6.1 Record the time of flame spread and type of burning observed for each specimen.
   • 6.2 Time of flame spread is the average for the 5 specimens.
   • 6.3 Base Fabric Ignition or Fusing - for fabrics with raised fiber surfaces, report this fact when more than 1 of 5 specimens perform this way or when more than 2 of 10.
   • 6.4 Report results shall be the flammability before or after dry cleaning/washing, whichever is lower. Classify the fabric per 1610.3 (smooth or napped).
   • 6.5 Classify into one of the following flammability classes:
     • Class 1, Normal Flammability - textiles which have no unusual burning characteristics.
     • Class 2, Intermediate Flammability - textiles having flammability characteristics between normal and rapid and intense burning.
     • Class 3, Rapid and Intense Burning - textiles considered dangerously flammable and unsuitable for clothing due to rapid and intense burning.
   • 6.6 Based on the time of flame spread, it is classified into one of the following 3 classes of Flammability:
     • Smooth fabric - the time of flame spread should be 3.5 seconds or more to classify as Class 1.
     • Smooth fabric - the time of flame spread is less than 3.5 seconds, then classify as Class 3.
     • Raised-fiber fabric - the time of flame spread should be 7.0 seconds or more to classify as Class 1.
     • Raised-fiber - if the raised fiber flashes on the base fabric but does not ignite, char or fuse, then classify as Class 1.
     • Raised-fiber fabric - if the flame spread id more than 4 seconds but not more than seconds, classify as Class 2.
     • Raised-fiber fabric - if the flame spread is less than 4 seconds and fabric ignites, chars, or fuses the base fabric, then classify as Class 3.

7. NOTE:

   • 7.1 Flammability apparatus is manufactured by the United States Testing Co., 1415 Park Avenue, Hoboken, NJ.
   • 7.2 Butane c.p. No. 4 cylinders containing 2 pounds of butane may be obtained from Matheson Co., Inc., East Rutherford, NJ.