What does flame spread 25 mean?

Flame Spread Rating Index = A numerical reference that measures how fast and far a flame spreads during a 10-minute test. Class A = Flame Spread Index of 25 or less; the best possible rating, awarded to fire-retardant building products, like concrete.

What is a good flame spread rating?

Class A – Flame-spread 0-25, smoke developed 0-450. Class B – Flame-spread 26-75, smoke developed 0-450. Class C – Flame-spread 76-200, smoke developed 0-450. NFPA 101 primarily applies this classification to interior wall and ceiling finish materials.

How is flame spread rating calculated?

From these observations a flame spread rating can be calculated. For example, if the flame travels 19-1/2 feet in less than 5-1/2 minutes (the time required for flame to spread on 19-1/2 feet of red oak), the rating is 100 times 5-1/2 divided by the time (minutes) in which flame spreads 19-1/2 feet on the sample.

What is a Class III flame spread rating?

The most commonly used flame-spread classifications are: Class I or A, with a 0-25 FSR; Class II or B with a 26-75 FSR; and Class III or C with a 76-200 FSR. In general, inorganic materials such as brick or tile are Class I materials.

What is ASTM E 84?

ASTM E84. ASTM E84, is also known as the steiner tunnel test, and tests the flame spread rating of Interior Finishes and Building Materials, specifically of wall and ceiling materials.

What is a Flame Spread Index?

Definition of flame spread index. The numerical designation that indicates the surface flammability of materials as specified by the ASTM E-162 test method ‘Surface Flammability of Materials Using a Radiant Heat Energy Source.’ U.S. Federal regulations require a flame spread index of 25 or less for flame-retardant coatings and sealants used in underground mines.

What is a flame spread?

Flame spread is the sliding movement of the flaming ignition point over the surface of a solid combustible.