NATIONAL BUREAU OF STANDARDS REPORT

i

1

f.

1320

FIRE-ENDURANCE AND HOSE-STREAM TESTS OF

PARTITIONS OF VERMICULITE- GYPSUM PLASTER ON

METAL LATH AND ON GYPSUM LATH

By

Jame s V • Ryan

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

This ref’ori: hss been prepared

1 0! 1 1 1 i y . . ..(.!) Vwv j Li nol to be referenced / Cj f /
NATIONAL BUREAU OF STANDARDS

A. V. As tin, Acting Director

U.. S. DEPARTMENT OF COMMERCE

Charles Sawyer, Secretary

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NBS PROJECT NBS REPORT

1002-43-1029 November 28, 1951 1320

FIRE -ENDURANCE AND HOSE-STREAM TESTS OF

PARTITIONS OF VERMICULITE- GYPSUM PLASTER ON

METAL LATH AND ON GYPSUM LATH

By

James V* Ryan

Fire Protection Section

Building Technology Division

... Approved for public release by the . . ,

. This report is issued . .

, T . „

an, reprinting, or reproduction

in any form, either in i Director Ol the National Institute ot [-mission in writing is obtained

fro® the office of the ] Standards and Technology (NIST) ashington 25, D. c. on October 9, 2015.
t- 1 • : V? . .r

‘i. : . . • . '* • .
FIRE-ENDURANCE AND HOSE-STREAM TESTS OF

PARTITIONS OF VERMICULITE-GYPSUM PLASTER ON

METAL LATH AND ON GYPSUM LATH

By

James Vo Ryan

ABSTRACT

The results of fire-endurance tests and hosestream tests on the various partitions in a group of five are reported,, Only two constructions are represented in the group however

They are a studless type partition of vermiculite-gypsum plaster on each side of gypsum

lath and a partition of the same plaster on

each side of metal lathe

The results of the fire-endurance tests showed

good consistency within the group. Hose-stream

tests on two duplicate partitions indicated

that these met the requirements of this test

for their respective fire-endurance limits. An

additional hose-stream test conducted at the

end of a fire-endurance test proved unsatisfactory for a longer fire-endurance limito

I, INTRODUCTION

Five solid partitions, all of nominal 2 l/2-in 0 thick

ness, were subjected to fire-endurance and/or hose-stream

tests. Two of the partitions were 16 ft wide and 10 ft

high, while the other three were 10 ft wide and 10 ft high

These tests were made in cooperation with the Vermiculite

Institute in order to establish fire-resistance limits for

the various cons tructions 0
2 -

2. MATERIALS

The gypsum lath, gypsum piaster, and plaster aggregate

were provided by the sponsor. The remainder of the materials

were provided by the contractor.

2.1 Plaster and Aggregate

The plasters used were two orders of a widely distributed

brand of fibered gypsum and the aggregate was an expanded

vermiculite . The chemical compositions and physical properties of the plasters were determined in accordance with the

methods prescribed by Federal Specifications SS-P-401 and

S3-P-402. Additional tests for physical properties were made

using a sample of the vermiculite aggregate. The results of

the chemical and physical tests are given in table L

The compressive strengths of 2-in. cubes of the plaster

batches applied to the partitions averaged 648 lbs per sq infor the scratch coats and 4l3 lbs per sq in. for the brown

coats

.

2.2 Gypsum Lath

The gypsum lath used was representative of the long length

varieties available. Its nominal dimensions were 1/2-in. thick,

2 ft wide, and 10 ft long. The results of strength tests (ASTM

Designation 026-42 and 037- 42 ) are given in table 2.
-3-

Table 1. Chemical and physical properties of fibered

gypsum plaster

Chemical Analvsis Tests 298-301 Test 307

% %

CaSO^ * 1/2 H

2 O (from loss) 83.2 9b .

CaSO^ • 1/2 H2 0 (from insol.) 92.8 94.6

CaSO^ • 1/2 H2 0 (from SO

3

) 93.1 93.6

CaS0p_ 0 1/2 H^O (average) 91

94.4

Phvsical Tests Tests 298-301 Test 307

SS--P-401 SS-P-402

Consistency ^9 19

Time of set 9 hr 7 hr 3 1/2 hr

Consistency for strength 49 21 1/3

Tensile strength 310

2

lb/in. 250 lb/in . 2

260 lb/in . 2

Compressive strength 1920 lb/in? 1320 lb/in . 2 1600 lb/in . 2

Physical Tests with Vermiculite Aggregate Tests 298-301 Test 30

Consistency 94.8

Time of set”^ 4 1/2 hr 2 1/4 hr

Tensile strength 105 lb/in . 2 80 lb/in . 2

Compressive strength 210 lb/in . 2 280 lb/in . 2

1/ It is believed that these low times of set are actually times

of quick stiffening observed in previous experience with

vermiculite aggregate in gypsum plaster.
-4-

Table 2. Character! sties of gypsum lath. •

Thickness Breaking Load

Nominal Measured

(avg)

Par a1

avg

lei to fiber

min

Across

avg

fiber

min

in. in. lb lb lb lb

1/2 .500 43.2 42.4 154.8 153.8

ASTM 1/2 .500 ± .031 40 40 100 100

req.

2.3 Metal Lath

The metal lath was a nominal 2.5 lb/per sq d diamond

mesh flat expanded metal lath.

2.4 Other Metal Products

The support for the metal lath was provided by 3/4“ by

1 /2 -in. 16 ga channels (3/4~in, cold rolled furring channels)

which also provided the bottom support for the gypsum lath.

Other support for the gypsum and metal lath was provided by

6 -in. wide strips of 2,

lb per sq yd diamond mesh flat expanded metal lath bent lengthwise in the center (cornerite).

All ties were made with 18 ga soft annealed galvanized wire.

The bottom of the plaster was protected by a pair of 2- by

1 /2 -in. channels or a pair of 2 1 /2 -in. wide formed sheet

metal strips placed one on each side of the base of the

partition as shown in the construction drawings.

3. CONSTRUCTION

The partitions were constructed by a local contractor's

employees with supervision by a representative of the sponsor
~ 5

~

and personnel of the National Bureau of Standards- The workmanship was of good quality and representative of that ordinarily obtainable- The construction details are shown in

figures 1 and 2.

3.1 Tests 298, 299, and 307

The construction details for tests 298, 299, and 307

differed only in the area of the face of the partition, all

being built to the same design which called for metal lath

supported by channels and plaster sufficient to form a partition of 2 1/2-in. nominal thickness. The partition for

h i gf h test 298 was 16 ft wide by 10 ft long-; those for the other

two tests were 10 ft square.

(a) Lath Foundation and Lath

Lengths of 3/!+-in. cold rolled furring channel were

secured to the inside faces of the test frame opening.

Channels were then erected vertically l6-in. o.c. and secured to those already placed across the top and bottom.

Since the channel came in 8 ft 8 in, lengths, it was

necessary to overlap two pieces of channel for each 10 ft

height. Additional support was provided by the cornerite

on the to-be-exposed face all across the top and down each

side. A framework of horizontal channels and 2 x ^'s was

erected for temporary support during the application of the

lath and scratch coat plaster.
6 -

The expanded metal lath was tied to the channel with

single ties of wire approximately 6-in, apart, The long dimension of the lath was horizontal and each lath lapped its

neighbor about 3-inc The laths were tied along the lap

joints and to the cornerite along the top and sides

,

The channel or metal strip for the protection of the

bottom of the plaster was mounted as shown in figure 1 and. se

cured by various methods, including bolts, at the discretion

and request of the sponsor

„

(b) Plastering

The grounds were set for the desired thickness of plaster, 1-in. between the lath and the exposed face and the remainder backing the lath. The scratch coat plaster, mixed.

2 cu ft of vermiculite to each 100 lb bag of gypsum plaster

(1 1/2 cu ft), was applied to each side of the lath and

allowed to set. Then the temporary framework of 2 x Vs and

horizontal channels was removed and the brown coat, mixed 3

cu ft of vermiculite per 100 lb bag of gypsum plaster, was ap

plied to each side. After the brown coat had set a. l/16-in,

white finish coat of 3 parts of lime putty to 1 part of

gaging plaster by volume was applied to each side to bring

the surface out to the grounds. The space inside the metal

protection at the bottom was filled with the scratch coat

plaster.
7

Pig

1,

Construction

details

of

the

test

partitions

- 8-

Fig 2.. Partition for test 298 at start of plastering.

The wood members and horizontal channels were

temporary bracing.

- 9

-

3.2 Tests 300, 301

The construction details of the two partitions differed

only in the area of the face of each, that for test 300 being

16 ft wide by 10 ft high while that for test 301 was 10 ft

square o Both were built from the same design which called

for 1-in. of plaster on each side of l/2-ino gypsum lath.

(a) Lath Foundation and Lath

Lengths of 3/li--in. furring channel were secured to the

bottom of the test frame opening and cornerite was attached

to the sides and top of the opening. The 10 ft lengths of

1/2-in. gypsum lath were erected vertically with the bottom

ends in the open side of the channel and one face of the

tops against the vertical leg of the cornerite. Each of the

end laths was similarly against cornerite along one edge.

The laths were tied together at 2 l/2-ft intervals along

their joints and to the cornerite at the ends and top. The

metal for the protection of the bottom of the plaster was

secured by bolts at the direction of the sponsor.

A temporary framework of steel channels was erected

against one face of the gypsum lath to provide support during the scratch coat plastering.

(b) Plastering

The grounds were set for 1-in. of plaster on each side

of the 1/2-in. gypsum lath and the scratch coat, mixed 2 cu

ft of vermiculite per 100 lb bag of gypsum plaster, was
applied to each side, scratched, and allowed to set. During

the application of the scratch coat, the space inside the

metal protection at the bottom was completely filled. After

the scratch coat plaster had set, the framework of channels

was removed and the brown coat, mixed 3 cu ft of vermiculite

per 100 lb bag of gypsum plaster, was applied. The 1/16-in.

white coat, mixed 3 parts of lime putty to 1 part of gaging

plaster by volume, was applied to give 1-in. of plaster on

each side and a total thickness of 2 1/2-in. for the partition.

3.3 Seasoning and Measuring

The various test specimens were allowed to age from 3b

to 55 days before test. During the aging period and after the

specimens had approached equilibrium conditions, measurements

of the actual thickness were made by drilling small holes

(lA-in. or less aiam) and measuring through them. The 16- by

10 ft partitions, intended for fire endurance testing, were

drilled at the nine points determined by the intersections of

the horizontal and vertical center lines and quarter point

lines. The 10- by 10 ft partitions intended for fire- and

hose-stream tests, were drilled only at the center point with

the exception of the partition for test 307 which had been

very carefully checked during construction by the representative of the sponsor. Once the measurements were taken, the

holes were filled with plaster.
- 11 -

Table 3. Measured Thicknesses of Partitions

Test

No. S.iza One-point Average (9) Max Min

ft in. in. in. in.

298 16 x 10 --- 2.45 2 1/2 2 7/16

299 10 x 10 2 3/8 -- -- --

300 16 x 10 ___ 2.25 2 7/16 2 3/16

301 10 x 10 2 1/2 — — — :/

307 10 x 10 -- 2.71 2 2 9/32 2 5/8

4. Test Method and Equipment

The tests were conducted in accordance with the Standard

Methods of Fire Tests of Building Construction and Materials

of the American Standards Association, ASA No. A2.1-1948

(ASTM Designation: E119-47)°

4.1 Wall-Testing Furnace

The tests were made in a furnace having a combustion

chamber 2 1/2-ft deep, 16-ft long, and 19 1/2-ft high. The

chamber extended 6 ft below the burners in order to provide

room for debris that might fall from the test specimen and

block the burners. The details of the construction of the

furnace are given in figure 3. One side of each partition

was exposed to fires controlled to conform closely to the

standard method which specified temperatures as follows:

2/ These measurements for test 307 taken several weeks

after the test.
1,000°F at 5 min

1,300°F at 10 rain

1,550°F at 30 min

1,700°F at 1 hr

1,850°F at 2 hr

and increasing 75 deg F per hour, thereafter. The test fire

was produced by 92 gas burners. The fire-endurance tests were

continued until one of the following criteria that limit fire

resistance was obtained: (a) fire damage sufficient to allow

the passage of flame or gas hot enough to ignite cotton waste,

(b) the transmission of heat through the partition sufficient

to raise the average temperature on its unexposed surface

250 deg F as measured by five or more thermocouples under 6-in.

square 0.4-in. thick felted asbestos pads, or (c) a 325 deg F

rise at any one of the above thermocouples.

4.2 Temperature Measurements

The temperatures inside the furnace, and on the unexposed surfaces of the partitions subjected .. fire-endurance

tests were measured at regular intervals by chromel-alumel

thermocouples and indicating potentiometers. The nine thermocouples in the furnace were protected by porcelain insulators

and encased in wrought iron pipes sealed at one end. Those on

unexposed surfaces were protected by asbestos sleeving and a

length of 6-in. , including the junction, was coiled under 6-in.
- 13-

SEOT!ON LONGITUDINAL SECTION HALE ELEVATION

kVtA

V'y ' 9

/// 1''^- u\ Sill'

hV\\ M

Fig 3. Panel test furnace.

A, furnace chamber; B, burners; C, thermocouple protection

tubes; D, pit for debris; E, observation windows; F, air

inlets; G, flue outlets and dampers; H, firebrick furnace

lining; I, reinforced concrete furnace shell; K, gas cocks;

L, control valve; M, ladders and platforms to observation

windows; N, movable fireproofed test frame; 0, test partition;

S, asbestos felted pads covering thermocouples on unexposed

surface of test partition.

square asbestos pads. The ocations of thermocouples are

given in figure 3. No surface thermocouples were located

within 6~in. of the points at which holes were drilled for

thickness measurements

4. 3 Deflections

The deflections of the partitions were measured during

the tests at nine locations on the unexposed surfaces. They

were obtained at frequent intervals by measuring from the

surface to wires hung in front of the test partition. One

of these wires was opposite the vertical center line of the

partition and one opposite the quarter point on each side

of the center line.

4o4 Hose Stream

To qualify for fire-endurance limits of 1-hr or more,

partitions are required to be subjected to a hose-stream test.

This test is ordinarily made by subjecting a duplicate partition to a fire exposure equal to half the desired fireresistance limit or half the fire-endurance limit of the

original partition, but not more than 1 hr. The partition is

then removed from the test furnace and immediately exposed

to the impact, erosion, and cooling effects of a fire hose

stream directed first at the middle and then at all parts of

the exposed face, changes in direction being made slowly. An

optional program permits having the hose-stream test made on

the sample subjected to the fire-endurance test and imme-
- 15-

diately following the expiration of the fire-endurance test.

This option was followed in test 299»

The stream is delivered through a 2 1/2-in. hose discharging through a National Standard Playpipe equipped with

1 1/8-in. discharge tip. The water pressure and duration of

application are governed by the fire exposure period. For

the three hose-stream tests (299? 301, 307), the stream was

delivered from a pressure of 30 Ih/sq in. and applied to the

100 sq ft of each partition for 2 1/2 min.

5. RESULTS OF TESTS

5.1 Test 298

Fire-endurance test of a 16 ft w

r ide by 10 ft high solid

partition of vermiculite -gypsum plaster on both sides of

metal lath to give an overall thickness of 2 1/2-in. (nominal) 0

(a) 'Test Log

Test Time

02

10

13

lb

Qbservation

Full height hairline crack on vertical

center line, unexposed side.

Diagonal hairline cracks in bottom corners

plus three verticals in south half.

Metal, channel on fire-exposed side bulges

out from partition near south end.

Hairline cracks in un^xposed side are

closing
-16-

Test Time Observation

28 Metal channel on fire-exposed side

bulges out from partition near north end.

30 Vertical crack 3 ft long from base at

south quarter point cf exposed surface.

42 Vertical crack 8-in. long from the base

at center point of exposed surface.

52 Diagonal hairline cracks reappear in

lower corners of unexposed surface.

58 Steam from 1/16-in. crack in lower north

corner of unexposed surface.

1:05 Diagonal cracks in all corners plus verticals along center line and 1 ft north

of center line of unexposed surface.

1:26 Horizontal crack 6 ft long and 1/16-in.

or less wide at center height of exposed

surface. Cracks in unexposed surface

1/16 in. or less.

1:28 Lower two-thirds of unexposed surface

darkened (apparently moisture) except

over the vertical channels.

1:34 Five horizontal cracks across unexposed

surface

1: 56

2:11

Partition "dished" toward flames; cracks

over most of unexposed surface; only two

fine cracks in exposed surface.

Gas off.

•

2:11
-17-

(b) Condition after test

The partition had deflected towards the furnace chamber,

showing a very pronounced "dishing" effect. The deflections

of the center point are shown in figure 4. Both the exposed

and unexposed surfaces showed considerable numbers of cracks

but none of the cracks were as much as 1/8-in. wide. No

piaster had fallen,

(c) Temperatures

The initial temperature was 8l°F (27° C). The furnace

temperatures are indicated by F and the unexposed surface

temperatures by S in figure 5* The severity of the fire exposure, as measured by the ratio of the area under the curve

of average furnace temperatures to the area under the reference curve, was 100.2 percent. Failure was determined by a

rise in temperature at one point of the unexposed surface

of 325 deg F (l8l deg C) , occurring at 1 hr 51 min. At that

time the average furnace temperature was l84l°F (1005° C),

5.2 Test 299

Fire-endurance and hose-stream test of a 10- by 10 ft

solid partition of vermiculite-gypsum plaster on both sides

of metal lath to give an overall thickness of 2 1/2-in.,

(nominal)

0
DEFLECTION,

INCHES

-18-

UJ

trQ

GTiO

LU

cr

o

cr

I

TIME, HOURS

DEFLECTION OF TEST PARTITIONS

Fig Deflections of the midpoints of the partitions during

the tests.

19

0o‘3HniVd3dlA!3i

do *3dniva3diAi3i

Fig

5

>.

Curves

of

temperatures

observed

during

the

tests

of

the

partitions

of

plaster

on

metal

lath.

F,

F

max

,

and

F

m^

n

refer

to

average,

maximum,

and

minimum

furnace

temperatures

respectively.

S

and

S

ma

refer

to

average

and

maximum

temperatures

on

the

unexposed

-20

(a) Test Log

Test Time Observation

02 1/2 Vertical hairline crack near center .line

of unexposed surface.

08 Several hairline cracks over unexposed

surface; 5-in. vertical crack near south

quarter point of exposed surface.

10 Flame from crack in exposed surface.

18 Less flame, black smoke from crack in

exposed face.

21 Metal base bulged toward flames for

about 1 ft near north end of exposed

side

23 Flame stopped and smoke almost stopped

from crack in exposed surface. Several

hairline cracks in unexposed surface are

outlined by moisture in plaster.

53 Crack in exposed surface glowing; cracks

in unexposed, surface less than 1/16-in.

wide

1:10 Except for outline of vertical channels

and some cracks, most of the unexposed

surface is darkened, apparently by

moisture
21 -

Test Time Observation

1:20 Horizontal cracks across unexposed surface about midheight are l/l6~in. wide;

others less.

1: 35 Horizontal crack across exposed surface

near top.

2:00 Gas off.

2 : Ok Hose stream applied to exposed surface

for 2 1/2 min.

(b) Condition after test

Following the hose-stream test, the exposed surface

white coat and brown coat plasters were badly eroded and, in

some places, even the scratch coat was partly eroded. The

metal lath was exposed for about 6 ft along a vertical line

about 2 ft from the north end and varying from 1- to 6-in.

wide. It was also exposed along two narrow horizontal

cracks and two small spots at the south edge. See figure 6.

The unexposed surface had a vertical crack opposite the 6 ft

eroded portion of the fire-exposed side. See figure 7. Water

had passed through the partition along this crack. The

partition was bowed away from the direction from which the

flames and hose stream had been directed.

(c) Temperatures

The initial temperature was 8l°F (27° C). The furnace

and unexposed surface temperatures are indie, ted by F and S,

respectively, in figure 5* The severity of the fire exposure
-22 -

Fig 6. Test 299* Exposed surface of partition after fire endurance and

hose stream tests.

Fig 7* Test 299* Unexposed surface of partition after fire

endurance and hose stream tests.

was 100o2 percento Failure was determined by a rise in temperature at one point of the unexposed surface of 325 deg F

(l8l deg C), occurring at 1 hr ^9 min. At that time the

average furnace temperature was l839°F (1004-°C).

5. 3 Test 307

Fire- and hose-stream test of a 10- by 10 ft solid

* partition of vermicuiite- gypsum plaster on both sides of

metal lath to give an overall thickness of 2 1/2-in.

(a) Test Log

Test Time Observation

03 Vertical hairline cracks near north

end of unexposed surface.

lb Some white coat plaster spalling from

exposed surface.

17 Five-in. vertical crack near top

center of exposed surface. Hairline

cracks in unexposed surface have

closed.

23 More white coat plaster spalling from

exposed surface.

51 Vertical cracks near each end of un1:00

exposed surface.

Gas off.

1:02 1/2 Hose stream applied to exposed surface

for 2 1/2 min.
2k-

(b) Condition after test.

Following the hose-stream test, the exposed surface

white coat plaster was gone from at least three-quarters of

the area but the brown and scratch coats were largely intact «, The metal lath was exposed in one spot 1 ft wide by 2~in s high as shown in figure 80 The plaster of the unexposed

surface was intact and dry, no water having passed through

the partition.

(c) Temperatures

The initial temperature was 79° F (26°C)o The furnace

temperatures are indicated by F in figure 5° The fire exposure severity was 99- *+ percent. The highest average furnace temperature was 1733°F (9^5°C), at the end of the fire

exposure

Test 300

Fire-endurance test of a 16 ft wide by 10 ft high solid

partition of 1 -in. of vermiculite-gypsum plaster on each

side of 1 /2 -in. gypsum lath to give an overall thickness of

2 1 /2 -in. (nominal).

(a) Test Log

Test Time Observation

03 Vertical hairline crack in unexposed

surface 2 ft south of center (corresponds to joint between two laths ) 0
-25"

Fig

8

C

Test

307*

Exposed

surface

of

partition

after

fire

and

hose

stream

test.
I / * \
~ 2 ( -

Test Time

10

25

4l

43

45

47

52

55

1:05

Observation

Vertical hairline cracks in unexposed

surface along lines of three joints

between laths * Hairline cracks in unexposed surface

have closed.

Metal base bowed toward flames near

north end of exposed side.

Several short cracks in random directions along a vertical path about 2 ft

from the south end of the exposed surface .

An L-shaped crack with each leg 2 ft

long at midheight and 4 ft from south

end in the exposed surface.

A crack in the form of an inverted T

at midheight 4 ft from north end in

exposed surface.

Vertical crack 3 ft long in exposed

surface 6 ft from south edge.

Horizontal cracks in exposed surface

1 ft from top and at midheight.

Inverted T and L-shaped cracks 1/8-

to l/4~in. wide, slight bulge at each.
“27~

Test Time

1:25

3Q^ /

1 : 4-6

1:50

1:53

1: 57

2:00

Observation

Vertical crack 6 ft long in unexposed

surface 6 ft from south edge, opposite

similar prack in exposed surface.

Plaster offset 3/8 in, along inverted

T crack in exposed surface. Horizontal

crack near top 1/4- to 3/8 -in. wide.

At inverted T and L -shaped cracks in

exposed surface, piaster below crack

offset 3/8- to 1/2-ino from that above.

Asbestos pad over thermocouple near

north quarter point on horizontal

center line (t'Jo. 6) fell.

Cotton waste glows after being held

over junction of horizontal and. vertical cracks 6 ft from, south edge at midheight.

Plaster offset 1- to 1 l/4-in.o towards

flames at L -shaped and inverted T

cracks in exposed surface. Unexposed

*

* surface has horizontal cracks at midheight and upper quarter point and vertical ever, 2. ft.

Gas off.
-28-

(c) Condition after test

Both surfaces contained numerous long cracks* Most of

the vertical cracks were spaced uniformly at 2 ft intervals

corresponding to the joints between laths. Despite the

numerous cracks, no plaster fell except small amounts of

white coat from the exposed surface* The partition had deflected away from the flames during the test, as shown in

figure 4.

(c) Temperatures

The initial temperature was 72° F (22° C), The furnace

and unexposed surface temperatures are indicated by F and

S, respectively, in figure 9 « The severity of the fire exposure was 100 percent. Failure was determined by a rise

in temperature of 325 deg F (l8l deg C) at one point on

the unexposed surface and ignition of cotton waste over a crack at another point, both occurring at 1 hr 53 min. At

that time the average furnace temperature was 1882°

(1006°C)

5*5 Test 301

Fire- and hose-stream test of a 10 ft square, solid

partition of 1-in. of vermiculite-gypsum plaster on each

side of 1/2-in. gypsum lath.
(a) Test Log

Test Time Observations

08 Several hairline cracks along edges and

in corners plus two verticals, one on

each side of center and 1 ft therefrom,

in unexposed surface <, 15 Metal base bowed toward flames at north

end of exposed side.

19 Hairline cracks in unexposed surface

almost closedo

35

9 Thin black smoke from 1 l/2-in» crack

1 to 2 ft below and north of center in

exposed surface.,

37 Light brown discoloration of unexposed

surface along hairline cracks «, 40 Several smoking cracks radiating from

previous crack in exposed surface,

covering an area of 1 1/2 ft diameter

which is also bulging.

50 Crack in exposed surface 1/4 in., wide

at center of radiating cracks

1:00 Gas off.

1:02 1/2 Hose stream applied for 2 1/2 min.

(b) Condition after test

Nearly all the white, brown, and scratch coats of plaster

were eroded from the exposed surface by the hose stream In
TEMPERATURE,

-30-

Pig 9. Curves of temperatures observed during the tests of partitions

of plaster on gypsum lath. P, Fmax , an<^ ^min re f“ er to average,

maximum, and minimum furnace temperatures respectively. S and

Smax refer to average and maximum temperatures on the unexposed

surface

;

Pig 10. Test 301. Exposed surface of partition after fire and hose stream

test.

TEMPERATURE,'
#

-

/
- 31-

addition, the gypsum lath was eroded in several small spots

but none larger than 1 ft square® See figure 10® The plaster on the unexposed side of the lath was not damaged by the

hose stream and no water passed through the partition.

(c) Temperatures

The initial temperature was 100° F (38°C). The furnace

temperatures are indie; ted by F in figure 9* The fire exposure severity was 100® 3 percent. The average furnace temperature was l67^0 F (912°C) just before the end of the fire

exposure .

6. DISCUSSION

In each of the tests 298 , 299? and 300, the specimens

failed to exhibit a 2-hour fire resistance period by only a few minutes o In each case the partition was slightly

thinner than the nominal 2 l/2-in. thickness intended. Extra

polation of the data provides an indication of results to be

expected from partitions of the full 2 l/2-in. thickness.

While the relationship between fire-endurance and struc

ture thickness for complex partitions is not too well understood, it has been customary to express this relationship

for simple partition structures 3 :
where

V

= Fire resistance period for the structure

tested

R = Derived fire-resistance period

2

T = Thickness of specimen tested

1

T = Thickness of specimen for which the derived

2

resistance period is required.

Using this formula and the average partition thickness the

derived fire-resistance periods listed in Table 4 may be obtained . Table 4. Derived fire-resistance periods 2 1/2-ino

partitions

Test

No.

Average

thickness

Observed fireendurance

Derived fireendurance

in. hr : min hr : min

298 2.45 1:51 1:55

299 2.38* 1:49 1:59

300 2.25 1:53 2:15

*0nly one thickness measurement was made on this panel
These derived fire-resistance periods may be considered

as estimates of the performance of partitions built in a similar manner to those tested but having average thicknesses

of 2. 50 in., the designed thickness of these partitions,

7 . SUMMARY

The partitions of plaster on metal lath of tests 298 , 299, and 307, were subjected to fire-endurance tests in the

first two instances and reached the end point of a 325 deg F

temperature rise at one point on the unexposed surface at

1 hr 51 min and 1 hr *+9 min, respectively. These specimens

would qualify for derived fire-resistance periods of 1 hr 55

min and 1 hr 59 min, based on an average thickness of 2,50 in.

The second specimen, test 299, was subjected to a hosestream test following the fire endurance, as permitted in

the optional program of the ASTM Standard Test Methods for

walls and partitions (ASTM E119-I+7 par. 9(c)) and failed to

prevent the passage of water through it. The third test of

the group, test 307, was a fire exposure of 1 hour followed

by a hose stream application in which no water passed through

the partition. This latter specimen meets the ASTM test requirements for a hose-stream test on a specimen qualifying

for a 2 hour fire-endurance limit.

The partitions of vermiculite-gypsum plaster on gypsum

lath of tests 300 and 301, were subjected to a fire-endurance
test in the first instance and a fire exposure and hose-stream

test in the latter. The former test reached the end point of

a 325 deg F rise at one point on the unexposed surface at 1 hr

53 min. This specimen would qualify for a derived fire-resistance period of 2 hr 15 min, based on an average thickness of

2.50 in. The latter test, with the hose stream applied

following 1 hr fire exposure was satisfactory, no water passing

through the partition. This latter specimen meets the ASTM

test requirements for a hose-stream test on a specimen qualifying for a 2 hr fire-endurance limit.
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