Fire Hazard Classification Tests of Interior Finish Materials

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Technical Note (National Research Council of Canada. Division of Building Research), 1971-02-01

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Fire Hazard Classification Tests of Interior Finish Materials

Rose, A.

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DIVISION OF BUILDING RESEARCH

No.

NATIONAL RESEARCH COUNCIL OF CANADA

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558

NOTlE

PREPARED BY

A. Rose CHECKED BY G. W. S. APPROVED BY

A.G.W.

PREPARED FOR _{The Fire Test Board.}

February 1971.

SUBJECT

FIRE HAZARD CLASSIFICATION TESTS OF INTERIOR

FINLSH MATERIALS

The National Building Code 1970 and CSA Preliminary Standard Z 240.2-1970(1) require a maximum flame spread rating

(ASTM E84-68) of 150 for interior finishes in certain cases. Supplement No. 2 to the National Building Code 1965(2), which is

slated for revision this year, lists generic flame spread ratings (Table 3.1. 1) for typical interior finish materials with conventional surface treatments, including wallpaper and burlap.

In the light of previous work (3, 4) by the Fire Section a few of these generic ratings, particularly for painted fibreboard. raw and painted hardboard, and raw particleboard. should be

revised. This Note presents the results of recent work on types

of interior finish materials not specifically covered by our earlier publications or by Supplement No.2. such as prefinished decorative

plywoods and hardboards. In addition, several unfinished hardboards

and particleboards were rechecked because of their inherent variability and because of improvements in the NRC/DBR tunnel furnace in the interim. particularly in the measurement of "Smoke Developed" (SD). The smoke rating is important now because of the inclusion of

maximum SD values for certain occupancies in the 1970 NBC. Because of the high flame spread ratings of some of the

materials, the effectiveness of a well-known UL-listed fire-retardant varnish system of the chlorinated alkyd type in reducing the

flamma-bility of a few of these materials was studied. A number of inquiries

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2

-investigations of fires involving varnished particleboards in basement corridors of apartments.

MATERIALS, SAMPLING AND METHOD OF TESTING

All materials were purchased on the open market as 4- by

8-ft panels. The prefinished hardboards and plywoods were grooved.

with the exception of the PVC -surfaced hardboard (Sample 113). Sampling. conditioning and testing were carried out as described

in Fire Study No. 22. (3) The ignition time IT (in seconds) is not

required by ASTM E84-68 but is usually recorded by most operators. Where rechecks of certain materials are involved, the

alphabetical coding used in Tables II and III of Fire Study No. 22 is repeated to facilitate comparison, and the numbers in brackets in the descriptions of materials in this report are those of the corresponding samples in the above-mentioned Tables.

The low-gloss chlorinated alkyd varnish (V -1) mentioned above adhered poorly to most of the prefinished plywoods and

hardboards. A "tie coat" of a compatible fire-retardant semi-gloss varnish (V -2) was applied in such cases to improve adhesion to the

substrate. In the case of the prefinished elm plywood (Samples 124

and 125), V -Z was also used as a topcoat. All varnishes were

applied by roll coater at the coverages indicated in Tables I and II, which are the averages for the two 4- by 8 -ft panels required for

each tunnel test. The oil-modified satin urethane varnish (V -3)

used on particleboard samples 139-146 was applied at 350-400 sq ft/gal.

In one case (Sample 130) the fire-retardant varnish coatings

were UL-listed two-component urethane types. The gloss topcoat

(V -5) was used as a sealer on sanded particleboard B. and the intumescent semi-gloss varnish V -4 was applied in two coats at a total coverage of 200 sq ft/gal.

RESULTS

Agreement between ratings obtained with the DBR/NRC tunnel furnace and that of Underwriters' Laboratories of Canada at Scarborough, Ontario, has been shown to be satisfactory in

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thickness. Flame spread ratings in the critical 150 range reported

here may thus be accepted with some confidence. Agreement on

"fuel contributed" and "smoke developed" values was also satisfactory,

probably because they were relatively low. The maximum obscuration

recorded on our smoke curves was about 40 per cent for these

particleboard runs, and comparisons in this range (SD of 150 -200)

are probably valid.

When the obscuration exceeds 40 per cent for a substantial portion of the test or 100 per cent obscuration occurs for brief intervals, inter lab comparisons or rejection of a material on the

basis of its SD value may be less arguable.

In this report a few SD values are recorded as > X. This

indicates that a high peak or total obscuration occurred briefly during the test, and that these values should be considered as semi-quantitative.

CONCLUSIONS

Prefinished hardboards from all four Canadian sources, thin prefinished plywoods from two major Canadian and two foreign sources, and most of the unfinished particleboards tested have given flame

spread ratings above 150.

Earlier work (3, 4) has shown that cellulosic fibreboard

tiles and panels from all four Canadian sources, when factory-finished or subsequently coated with conventional latex- or solvent-based

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4

-REFERENCES

1. Canadian Standards Association. Preliminary Standard

Z 240.2-1970. Structural requirements for mobile housing.

Section 6. 3. 1.

2. Fire Performance Ratings 1965. National Research Council

of Canada. Associate Committee on the National Building

Code of Canada, 1965. Ottawa. NRC No. 8330.

3. Rose A. Comparison of Flame Spread Ratings by Radiant

Panel, Tunnel Furnace and Pittsburgh Corning Apparatus. National Research Council of Canada. Division of Building Research,

Fire Study No. 22. June 1969. NRCC 10788.

4. Rose. A. Flammability of Fibreboard Interior Finish

Materials. National Research Council of Canada, Division

of Building Research, Building Research Note No. 68, October 1969.

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Hardboards and Plywoods

Sample _Description Coatings Applied ASTM E84-68 Results

No. ₁ ₂ ₃ FSC FC SO IT

110 Hardboard Y, l'Iominal 1/4 (0.230 in .)

---

135 94 210 60

unfinished [72 ]

111 Y, printed paper surface, 0.185 in.

---

209 135 >262 61

caliper

112 Y, III with F .R. coatings V-2 (580 ) V-I (161)

---

103 76 332 71

113 Y, 0.175 in., with embossed PVC

---

188 120 343 50

film overlay

114 Hardboard Z, nominal 1/4 (0.215 in. )

---

138 100 336 65

unfinished (75]

115 Z, 0.180 in. caliper,

---

182 119 >400 65

lithographed woodgrain finish

116 Z, 115 with F.R. coatings V-2 (580) V-I (157)

---

120 88 381 85

117 Hardboard P, nominal 1/4 (0.230 in. )

---

153 112 >265 63

118 P, 117 with F.R. coatings V-2 (580 ) V-I (153)

---

88 52 381 96

119 Hardboard Q, 0.185 in.

---

216 98 >190 55

120 Q, 0.230 in., lithographed

---

190 110 217 67

woodgrain finish

121 Plywood V, 4 mm (0.150 In.)

---

239 59 75 36

preflnlshcd birch, pine core

I?? V with F.R. coatings V-2 (580) V-I (162)

---

167 57 240 28

123 Plywood W, 4 mm (0.145 in. )

---

240 91 241 33

pre finished elm, lauan core

124 W with F.R. coatings V-2 (1200) V-I (250) V-2 (610 ) 70 22 114 10

125 W with heavier F.R. coating V-2 (1210) V-I (144) V-2 (570) 38 20 215 25

126 Plywood L, 4 mm (0.150 in. )

---

243 41 84 26

prefinished lauan

127 Plywood M, 4 mm (0.150 in. )

---

239 47 68 42

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,"

Table II Particleboards

Sample _Description Coatings Applied ASTM E84-68 Results

No. ₁ ₂ ₃ _PSC _FC _SD _IT

128 Particleboard B (82] 0.625 in.,

---

217 123 126 40

aspen flakes, phenolic binder

129 B, later production (1969)

---

242 131 149 43

130 129 with F.R. coatings V-5 (535 ) V-4 (204)

---

129 106 355 38

131 Particleboard K(48], 0.500 in.

---

169 116 147 57

cedar chips, urea resin binder

132 K, duplicate of 131

---

165 119 153 75

133 Particleboard R (46, 47, 85 ]

---

184 125 101 40

0.500 in. mixed

hardwood-softwood chips, urea resin binder

134 R, 0.500 in. , later production

---

165 111 95 63 (1969)

135 134 with F.R. coatings V-? ＨＵＶｾＩ V-I" (163)

---

70 30 258 120

136 R, 1970 production

---

131 109 161 51

137 R, 1970 production

---

141 114 164 54

138 R, 0.250 in.

---

176 103 83 43

139 R, 138 with satin varnish V-3 (328)

---

168 79 105 35

140 R, 139 plus F.R. coatings V-3 (65) V-I (140)

---

75 38 352 57

141 R, 0.375 in.

---

_---

---

217 125 85 52

---

117 115 128 41

---

75 36 350 55

144 R, 0.500 in.

---

184 119 84 53

---

200 116 82 37

---

73 46 246 52

Abbreviations Used (E84-68)

FSC - flame spread classification FC - fuel contributed

SD - smoke developed IT - ignition time (sees.)