NFPA 701: What is the Small Scale Test?

13.03.2012 § Leave a comment

(No. 1 of 3) When referring to drapery fire tests, we often hear people talk about the “vertical fire test” or “small scale”. The actual test code is NFPA 701. (NFPA stands for National Fire Protection Agency.) Since the test is done vertically, compared with, say, ASTM E-84 which is done with the fabric lying horizontally, NFPA 701 is nicknamed the vertical test.

The latest NFPA 701 version was updated in 2010, although its two test methods have hardly changed since 1996. We use NFPA 701 Test Method #1 for lightweight, single layer draperies. In this test, a hanging fabric is exposed to a 4” flame for 45 seconds; whether it passes depend on how much weight the fabric loses when it burns and whether any pieces that break off continue to burn. This second criterion is sometimes called drip burn.

For a long time, ACT used the 1989 version of NFPA 701 as the flammability guideline for draperies, and they only adopted the new version last year. The NFPA 701 test from 1989 was the small scale test. Even though people still say “small scale,” in a way the test itself is obsolete since it’s evolved into these later versions. The 1989 test used a smaller flame, and the fabric was exposed to the flame for less time. The criteria were different too. Instead of focusing on mass loss, the 1989 small scale test measured char length, which is exactly what it sounds like: how far up the fabric the flame spreads.

Below is a summary of the differences between the NFPA 701 tests. I will address Test Method #1 more in a later post, and maybe share some test results as an example.

Test Flame Pass Criteria
2010 Test Method #1 4 inches
for 45 seconds
No more than 40% mass loss
No more than 2 seconds drip burn
1989 Small Scale 1.5 inches
for 12 seconds
No more than 6.5” average char length
No more than 7.5” individual char length
No more than 2 seconds drip burn

If a fabric needs to be treated to pass 701, it’s possible that the treatment might allow it to pass one of these tests but not the other. A finisher’s formula may work for 90% of the fabrics they try, but the other 10% might need to go through 3 or even 4 different formulations before one of them works. Flame retardant treatments aren’t one-size-fits-all; and even with a finish, a fabric could pass one version of 701 but fall into that 10% for the other.

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