[SML] more on Foam Flame Retardant

[Bill Conner]

I posted this the other day but got a message from SML server it was
too big to post without moderator review.  I've deleted the
attachments which I think will bring it below the size limit.

I believe in the original post incident, the authority misspoke or was
simply wrong.  The 2015 Life Safety Code says:

12.4.6.11 Flame-Retardant Requirements.
12.4.6.11.1 Combustible scenery of cloth, film, vegetation
(dry), and similar materials shall comply with one of the
following:
(1) They shall meet the flame propagation performance criteria
contained in Test Method 1 or Test Method 2, as
appropriate, of NFPA 701, Standard Methods of Fire Tests for
Flame Propagation of Textiles and Films.
(2) They shall exhibit a heat release rate not exceeding 100 kW
when tested in accordance with NFPA 289, Standard Method
of Fire Test for Individual Fuel Packages, using the 20 kW ignition
source.
12.4.6.11.2 Foamed plastics (see definition of cellular or foamed
plastic in 3.3.41) shall be permitted to be used if they exhibit a
heat release rate not exceeding 100 kW when tested in accordance
with NFPA 289, Standard Method of Fire Test for Individual
Fuel Packages, using the 20 kW ignition source or by specific
approval of the authority having jurisdiction.
12.4.6.11.3 Scenery and stage properties not separated from
the audience by proscenium opening protection shall be of
noncombustible materials, limited-combustible materials, or
fire-retardant-treated wood.
12.4.6.11.4 In theaters, motion picture theaters, and television
stage settings, with or without horizontal projections, and in
simulated caves and caverns of foamed plastic, any single fuel
package shall have a heat release rate not to exceed 100 kW
where tested in accordance with one of the following:
(1) UL 1975, Standard for Fire Tests for Foamed Plastics Used for
Decorative Purposes
(2) NFPA 289, Standard Method of Fire Test for Individual Fuel
Packages, using the 20 kW ignition source

I am pretty certain UL 1975 is of limited use, as it is for a single
object, not just the material, and is very particular to that object.
An example is a block for a hat or wig might be tested to UL 1975.
FWIW, I recall being told that something like a single 2' X 8' X 2"
piece of XPS would probably pass as that, but cut it up and expose
more surface -maybe not.

I wish I could tell you what NFPA 289 does, but I'm not familiar with
it.  It appears to not be useful either, as it is for an object, and
not just a material.

I've *not* attached the official scopes of the current versions of each.

Now, a couple more anecdotal pieces.  I have on several occasions
shown the Assembly Occupancy committee pictures of foam uses.  My
favorite is a large - two story - house facade covered with
clapboards, basically hollywood flats with 1" X 4"clapboards, and they
do not seem to concerned.  Make of that what you will - perhaps lack
of concern is not knowing what to do.

I have also been directed to 12.7.4.3, which kind of conflicts with
12.4.6.11 but says:

12.7.4.3 Exposed foamed plastic materials and unprotected
materials containing foamed plastic used for decorative purposes
or stage scenery shall have a heat release rate not exceeding
100 kW where tested in accordance with one of the
following:
(1) UL 1975, Standard for Fire Tests for Foamed Plastics Used for
Decorative Purposes
(2) NFPA 289, Standard Method of Fire Test for Individual Fuel
Packages, using the 20 kW ignition source
12.7.4.4 The requirement of 12.7.4.3 shall not apply to individual
foamed plastic items and items containing foamed plastic
where the foamed plastic does not exceed 1 lb (0.45 kg) in
weight.

and the appendix note:

A.12.7.4.3 The phrase "unprotected materials containing
foamed plastic" is meant to include foamed plastic items covered
by "thermally thin" combustible fabrics or paint. (See A.10.2.3.4.)

which gets us to:

A.10.2.3.4 It has been shown that the method of mounting
interior finish materials usually affects actual performance.
The use of standard mounting methods will be helpful in determining
appropriate fire test results. Where materials are
tested in intimate contact with a substrate to determine a classification,
such materials should be installed in intimate contact
with a similar substrate. Such details are especially important
for "thermally thin" materials. For further information,
see ASTM E 84, Standard Test Method for Surface Burning Characteristics
of Building Materials.
Some interior wall and ceiling finish materials, such as fabrics
not applied to a solid backing, do not lend themselves to a
test made in accordance with ASTM E 84. In such cases, the
large-scale test outlined in NFPA 701, Standard Methods of Fire
Tests for Flame Propagation of Textiles and Films, is permitted to be
used. In 1989 the NFPA Technical Committee on Fire Tests
eliminated the so-called "small-scale test" from NFPA 701 because
the results had been shown not to represent a fire performance
that corresponded to what happened in real scale.
Since then, NFPA 701 no longer contains a "small-scale test"
but it now contains two tests (Test 1 and Test 2), which apply to
materials as a function of their areal density. Thus NFPA 701
Test 1 applies to fabrics (other than vinyl-coated fabric blackout
linings) having an areal density less than or equal to
21 oz/yd2 (700 g/m2), while NFPA701 Test 2 applies to fabrics
with an areal density greater than 21 oz/yd2 (700 g/m2), vinylcoated
fabric blackout linings, decorative objects, and films.
Representations that materials or products have been tested
to the small-scale test in NFPA 701 normally refer to the pre-
1989 small-scale test, which no longer exists and which does
not represent acceptable fire performance.
Prior to 1978, the test report described by ASTM E 84 included
an evaluation of the fuel contribution as well as the
flame spread index and the smoke developed index. However,
it is now recognized that the measurement on which the fuel
contribution is based does not provide a valid measure. Therefore,
although the data are recorded during the test, the information
is no longer normally reported. Classification of interior
wall and ceiling finish thus relies only on the flame spread
index and smoke developed index.
The 450 smoke developed index limit is based solely on
obscuration. (See A.10.2.4.1.)

I *think* that this leads to raw foam no good but foam covered with
joint compound or similar and maybe some FR fabric to hold the
compound on is OK, the goop being a "thermally thin" barrier.

If the code were to change, what would you like it to say?  What's
reasonable and practical foam scenery?

WARNING-COMMERCIAL: I plan to discus some of these issues at a panel
at USITT, Friday, 1:00 pm, Code Conundrums.  Steve Terry and Kim
Corbett Oates also.  Sorry I didn't schedule the get together with
adult beverages just prior to this event.

-- 
Bill Conner Fellow of the ASTC