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1 NRC Publications Archive Archives des publications du CNRC Fire tests on window assemblies protected by automatic sprinklers Richardson, J. K.; Oleszkiewicz,. This publication could be one of several versions: author s original, accepted manuscript or the publisher s version. / La version de cette publication peut être l une des suivantes : la version prépublication de l auteur, la version acceptée du manuscrit ou la version de l éditeur. For the publisher s version, please access the DO link below./ Pour consulter la version de l éditeur, utilisez le lien DO ci-dessous. Publisher s version / Version de l'éditeur: Fire Technology, 23, 2, pp , NRC Publications Record / Notice d'archives des publications de CNRC: Access and use of this website and the material on it are subject to the Terms and Conditions set forth at READ THESE TERMS AND CONDTONS CAREFULLY BEFORE USNG THS WEBSTE. L accès à ce site Web et l utilisation de son contenu sont assujettis aux conditions présentées dans le site LSEZ CES CONDTONS ATTENTVEMENT AVANT D UTLSER CE STE WEB. Questions? Contact the NRC Publications Archive team at PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. f you wish to the authors directly, please see the first page of the publication for their contact information. Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

2 Ser TH1 National Research Council Canada Conseil national de recherches Canada no c. 2 nstitute for lnstitut de BLDG Research in recherche en - - Construction construction Fire Tests on Window Assemblies Protected by Automatic Sprinklers by J.K. Richardson and. Oleszkiewicz Reprinted from Fire Technology Vol. 23, No. 2, - May p (RC Paper No. 1467) Price $3.00 NRCC NRC - CSTj RC LDWARY JAN? lpyl BBLOTHEQUE frc CNTC - lclst

3 RESUME C On d6crit des essais au feu en vraie grandeur effectuss sur des vitrages arm& et trempss, montes sur des chbsis d'acier et d'aluminium. Soumis 3 un feu normalis6, ces vitrages ont h prgsents une dur6e de rssistance a11 feu de 45 minutes 3 2 heures. La densit6 de flux de chaleur radiante maximum transmise par le verre a 6t6 reduite de plus de 90%. -.

4 Fire Tests on Window Assemblies Protected by Automatic Sprinklers By J. K. Richardson and. Oleszkiewicz National Research Council Ottawa, Canada Reprinted from FRE TECHNOLOGY Volume 23, Number 2 May, 1987 Copyright O National Fire Protection Association. All Rights Reserved.

5 Fire Tests on Window Assemblies Protected by Automatic Sprinklers J. K. RCHARDSON. OLESZKEWCZ National Research Council, Canada (Manuscript received July 1986, accepted September 1986) ABSTRACT Full-scale fire tests on wired and tempered glazing in steel and aluminum frames are described. These assemblies achieved fire resistance ratings when exposed to a standard fire of 45 min to 2 h. The maximum radiant heat flux transmitted through the glass was reduced by more than 90%. NTRODUCTON HE USE OF GLAZNG in fire separations has been strictly reg- T ulated by building codes, including the National Building Code of Canada (NBCC).' The NBCC 1985 edition, as with most North American model building codes, limits vertical glazing to wired glass in steel frames; individual panes must not exceed 0.84 m2 in area and must have a maximum dimension of 1.4 m. To the practicing design professional, these limits impose a severe restriction on the design of fire-rated assemblies where glazing is desirable or necessary. n particular, the emergence of the atrium building and the need for increased visual contact with building areas for security reasons has created a considerable demand for glazing in fire separations. To determine whether different types of glass, larger areas and dimensions, and different framing materials could be used, a series of fire tests was performed at the National Fire Laboratory of the National Research *. CoQncil of Canada. These experiments examined tempered and wired glass, single and double glazing, significantly larger areas and dimensions, and steel and aluminum frame materials, all in conjunction with automatic.- sprinkler protection. Reference: J. K. Richardson and. Oleskiewicz, "Fire Tests on Window Assemblies Protected by Automatic Sprinklers," Fire Technology, Vol. 23, No. 2, May 1987, pp Key Words: Sprinkler systems, wired glass, tempered glass. This pa er is a contribution from the nstitute for Research in Construction, National ~esearcf Council of Canada. '

6 116 Fire Technology BACKGROUND NFORMATON Background information for glazing materials exposed to fire is scarce, especially with respect to extended fire resistance ratings. n recent years, borosilicate glazing has been developed to resist the effects of fire.' Because of its high cost, this glazing is not frequently used in North America. There is also a demand for glass pane sizes larger than those available for this! product. A tempered glazing system protected by a deluge sprinkler arrangement was examined by Underwriters Laboratories in The system used large quantities of water and required a wetting agent. This glazing system was developed for a 45-minute standard exposure from outside the building as opposed to the NBCC criteria for fire exposure inside the building and for greater exposure times. Tests were also carried out by Moulen and Grubits in Australia on various glazing materials that were protected by drenchers when exposed to radiant heat.",' These tests demonstrated that such a system would reduce by 90% the radiant heat transmission through glazing materials exposed to a radiant heat flux of 40 kwlm2 (4 Wlcmz). The tests4 also showed that only wired and tempered glass withstood the radiant fire exposure long enough for glass bulb sprinklers with temperature ratings of 68 C and 93 C to activate. n the United Kingdom, a similar system using drenchers on glass 6 mm and 10 mm thick has been tested by the Greater London Council Scientific Services Bran~h.~ n these experiments, float and toughened glass stayed in place up to 70 min when exposed to the "slow heating curve" defined in DN Standard 4102, Part 3.' Based on this curve, a maximum of 650 C is reached at 10 min and maintained until the end of the test. TEST CRTERA After evaluating the published information and the needs of North American users, the following criteria were established for the test program. 1. The glazed assembly should use commonly available equipment and materials, and should not be sophisticated. 2. The assembly should be able to withstand a fire exposure as typified by the standard timetemperature curves for at least 2 h (at which time in the standard test the radiant fire exposure exceeds 10 Wlcm2) The panes should be as large as possible in both area and dimensions. 4. The sprinkler installation should have closed heads and use only water as a cooling agent (i.e., no wetting agent). DESCRPTON OF THE BURN FACLTY The tests were conducted in a 1.83 X 2.44 m burn room with a ceiling height of 3.05 m. Three of the walls of the facility, constructed of concrete

7 Fire Tests on Window Assemblies 117 block 152 mm thick, were protected on the inside with 25-mm refractory - thermal insulation (Fiberfrax blanket).* The fourth (east) wall was formed by the test window assembly erected on a foundation 0.2 m high. The ceiling assembly was constructed of 19-mm plywood supported on a wood frame with 38 X 89 mm members. The plywood was protected by 13-mm gypsum board, 13-mm marinite board, and two layers of 25-mm Fiberfrax blanket. The room was constructed on a sloping concrete floor (see Figure 1). To protect the floor and facilitate water drainage from the enclosure, the floor! was covered with crushed stone, and openings were made in the base of the test wall. 4 Gas Air e Control thermocouple Dimensions in mm Figure 1 Section of bum room. DESCRPTON OF THE GAS AND AR SYSTEMS Fire exposure was provided by a linear propane burner installed on the,. floor adjacent to the west wall (opposite the test assembly) as shown in Figure 1. The burner was protected from water spray and steam by a firebrick wall extending 0.2 m above the burner (0.65 m above the floor). - - Combustion products and steam were withdrawn through two stacks with a 0.6 X 0.45 m cross section, located in the north and south walls. To retain the hot gases in the room but remove the cooler steam, the exhaust *Trade names have been given for cetain products used in these experiments as a means of clarifying specific details. They are not intended as an endorsement of those particular products by the National Research Council of Canada, Fire Technology, or the National Fire Protection Association.

8 118 Fire Technology stack inlets were located near floor level. A sheet steel baffle was installed across the room on the burner side of the exhaust stack to prevent the steam from recirculating. Air to the burner was supplied at rates up to 0.9 m31s by a centrifugal forced-air fan with an adjustable damper. DESCRPTON OF THE TEST ASSEMBLES Three types of window assemblies were used, one for each test series. Specific details of dimensions and materials are included in Table 1. The window frame was installed in an assembly consisting of two layers of 12.7-mm Type X gypsum board on steel studs (see Figure 2). This wall assembly is listed as having a 2-h fire resistance rating. The hollow frame was made from 16-gauge, fully welded, galvanized steel with a 51-mm face, 171-mm jamb depth and 16-mm high integral glass stop. A standard 20-gauge removable glass stop, 16 mm high and 19 mm wide was fixed to the frame with self-tapping screws. Tempered or wired glass was installed in the frame using a sealant, shims, and rubber setting blocks, in addition to the glass stop. The glass was not cleaned except for small spots where thermocouples were bonded to the glass. Aluminum frames were installed in a gypsum board on steel stud assembly as shown in Figure 3. The side of the frame facing the burner was covered with 12.7-mm Type X gypsum board on a 38-mm steel stud. The side of the frame adjacent to the glass was left exposed. The hollow aluminum frame, Kawneer Model 1600, was approximately 3 mm thick, 64 mm wide, and 102 mm deep. The glass assembly consisted of a sealed double-glazed unit with clear, tempered glass on the fire-exposed side, and solar blue-tinted, ordinary Table 1 Details of window assemblies. -- Detail Series 1 Series 2 Series 3 Glazing Single, wired or Double, tempered Single, tempered tempered on the exposed side -. and ordinary tinted on the unexposed side Glass thickness 6 rnm 6 mm (each pane) 6 mm Glass pane dimensions 1560 X 1100 mm 2092 X 1512 mm 2601 X 1686 mm Exposed glass dimensions 1538 X 1078 mm 2073 X 1492 rnm 2592 X 1677 mm Frame pocket dimensions 1570 X 1110 mm 2105 X 1525 mm 2616 X 1708 mm Frame material Steel Aluminum Aluminum

9 Fire Tests on Window Assemblies D~rnenr~onr ~n rnm Figure 2 Series 1 test assembly. Figure 3 Series 2 test assembly. glass on the unexposed side. A sealant, shims, and 6-mm rubber setting blocks at the bottom edge were used. The glass was not cleaned except where thermocouples were attached. For the Series 3 test, the aluminum window frame was installed in gypsum board on a steel stud assembly as shown in Figure 4. The aluminum frame was exposed to the burn room. The hollow aluminum frame, Kawneer Model 450, was approximately 3 mm thick, 45 mm wide, and 114 mm deep. The tempered glass was installed in the frame; a sealant and shims were used, as well as 6-mm rubber setting blocks placed at the bottom edge. The *. glass was not cleaned except for small areas where thermocouples were attached.. - SPRNKLER NSTALLATON For the tests using sprinklers in Series 1 and for all tests in Series 2 and 3, prototype Grinnell sprinklers were located on the centerline of the glass. They were essentially Duraspeed standard and quick-response types with a deflector design to ensure that water would wet the entire glass surface, especially the upper corners.

10 120 Fire Technology F; Figure 5 Quick-response window sprinkler (series 2 and 3 tests). Figure 4 Series 3 test assembly. Figure 6 Thermocouple locations on the glass. The center of the sprinkler deflector was 32 mm below the lower surface of the top window frame member. The deflector face was 16 mm from the glass. Table 2 lists the sprinklers used in each test. With one exception, in Series 1, the prototype was a 12.7-mm orifice (K factor = 78). Grinnell Duraspeed sidewall sprinkler with a 74 C standard link (Designation RJA-1). n Test 1-8 and in Series 2 and 3, the prototype was a 12.7-mm orifice (K factor = 78), horizontal sidewall sprinkler with a 74 C quick-response link [Designation FR-1Q-60 (see Figure 5)]. Except for the link mechanism, the standard sprinkler was essentially the same as that shown in Figure 5. The water flow to the sprinkler, including any variations in flow, is noted.. in Table 2. NSTRUMENTATON The air temperature of the burn room was monitored by six Type K thermocouples (see Figure 1 for locations) enclosed in 6-mm outside diameter incone1 sheaths. The thermocouple beads were positioned 610 mm from the sidewalls. The distances between the glass and the thermocouples, and the vertical distribution of the thermocouples differed from the specifications of

11 Fire Tests on Window Assemblies Table 2 Summary of sprinkler system data. Sprin kler Activation Water Flow Test Glass Sprinkler Time Water Flow per m Width Duration Number Type' Type s) (L/min) (Wminl/m (min) 1-1 W RJA W RJA-1 34' T RJA-1 16' * 1-4 T RJA T RJA T None - 6.5' 1-7 T None ' d 1-8" W FR-1Q TP FR-1Q TP FR-lQ T FR-11QL ' W - wired; T - tempered; P - plain. Early sprinkler response due to excessively high initial temperatures (see text). "lass breakage time. Sprinkler on side not exposed to fire. CANkS101, "Standard Methods of Fire Endurance Tests of Building Construction and material^,"^ to minimize the influence of water spray on thermocouple readings. The standard test requires that the thermocouples be located 150 mm from the glass whereas in the tests these were located 1420 mm from the glass (beyond the water spray from the sprinkler). The preliminary tests showed that the temperature distribution in the room was symmetrical with respect to a vertical central plane. For this reason, the temperatures were recorded on one side only. The output signals from the three thermocouples on the other side were averaged and used as the basis for manually controlling the burner. Temperatures on the glass were measured at five points (Figure 6) on the unexposed side using 30-gauge chromel-alumel thermocouples bonded to the glass with a clear epoxy resin. n tests without sprinklers, a thermocouple was similarly bonded to the glass on the fire-exposed side. The window frame temperatures were measured on the exposed side as well as the unexposed side at the midpoint of each frame member. All thermocouple beads were fastened to the frame with self-tapping screws. Figure 7 shows the location of the thermocouples on a cross section of the frame *. used in the Series 1 tests. n the Series 2 tests, the thermocouples on the frame on the fire-exposed side were shielded by drywall, as shown in Figure 8. Figure 9 shows the location of the thermocouples on a cross section of the.. frame used in the Series 3 test. n some tests, radiation transmitted through the window was measured with water-cooled radiometers located opposite the window and either 0.6 m or 1 m from the glass. Air pressure inside the room was monitored with an inclined tube manometer installed on the south wall at two-thirds the room height. The water flow rate used during the tests was measured with a paddle-

12 122 Fire Technology Exposed side urn- side Unexposed sick Thermocouple,' A Figure 7 (top left) Series 1 thermocouple locations on side side the frame. Figure 8 (above) Series 2 thermocouple locations on the frame. Figure 9 (left) Series 3 thermocouple locations on the frame. -. wheel-type flow meter. Water pressure was monitored with a gauge connected to the branch line. TEST PROCEDURE Following activation of the air supply, the burner was lit. Gas and air controls were then adjusted manually to maintain the average temperature recorded by the three control thermocouples as close to the standard timetemperature curve as possible. The sprinklers were permitted to fuse normally. The water flow rate was set prior to the test, and was adjusted as required during the test. This adjustment was often made if dry spots formed on the fire-exposed face of the glass. Following the fire exposure and water shutdown in Test 3-1, the unexposed face of the glazed assembly was subjected to a nonstandard hosestream test using a 37-mm (1.5411) nominal diameter hose with a combination foglstraight stream nozzle. The hose was located 6 m from the glass, at right angles to it. The initial flow was 114 Llmin using a fog spray, followed quickly by a straight stream flow of 473 Llmin for approximately 1 min. This hose-stream test differed from that required in the standard testqn terms of the equipment used and the face to which the hose stream was applied. OBSERVATONS Sprinkler activation times are shown in Table 2. t should be noted that in Test 1-8 the sprinkler was located in the non-fireexposed side of the

13 Fire Tests on Window Assemblies 123 glass. n all tests, water from the sprinkler tended to cover the glass in a reasonably uniform pattern; however, at decreased flow rates, dry spots were noted in the center portion of the glass toward the bottom of the pane. n the Series 2 tests, the outer pane (plain glass) of the double-glazed assembly cracked early in the tests (after min); but the inner pane (tempered glass) remained intact. The cracked outer pane remained in place for the duration of the tests. 4 n all tests where wired glass was used, there was cracking of the glazing - prior to sprinkler activation and extensive cracking during the tests. n all cases, however, no noticeable openings appeared in the glass. Following the tests, minor warping of the upper frame member on the fire-exposed side was noticed. The tempered glass assemblies in Tests 1-6 and 1-7, which did not have sprinkler protection, failed at 5 min and 6.5 min. RESULTS AND DSCUSSON n the tests of tempered glass in which the sprinklers were located inside the burn room, glass breakage did not occur. Reasonably steady-state conditions were established in the second half of the tests, so it is anticipated that the assemblies could have withstood the standard fire exposure for greater times than those used in the tests. The Series 2 tests of double glazing were terminated at the times shown in Table 2 to reduce fire damage to the roof assembly; in these tests, the tempered glass on the fire-exposed side had not broken. n the tests of wired glass, glass cracking occurred prior to sprinkler activation. The test with the sprinkler outside the burn room resulted in a greater number of glass cracks, compared with the test where the sprinkler was inside the burn room, probably because of the higher temperature differential between the fire-exposed and unexposed faces. Although the top inside frame had warped more in the test with the sprinkler outside the burn room, there was no danger of failure. f sprinkler protection is used on either the exposed or unexposed side, it is expected that a wired-glass assembly can withstand the standard fire exposure for at least 2 h. The average temperatures in the burn room. as recorded on the three thermocouples, substantially followed the standard time-temperature curve. in all tests. Curves are shown in Figure 10 for Test 1-5, in Figure 11 for Test 2-2, and in Figure 12 for Test 3-1. The difference between the curves for the upper and lower thermocouples is primarily the result of steam and water spray from the sprinkler that were drawn back towards the burner in the lower portion of the room. Figure 13 shows the corresponding room temperatures when the sprinkler was located outside the bum room (Test 1-8). n Tests 1-2 and 1-3 it was impossible to maintain the average tempera-

14 124 Fire Technology ) ,._-..-.._..._ , , ,rr_-_s---~p--a Bottom R m temperatures fop / ,...-. ' Mid STO cuke --,, /<- -J-4./\r/-A-14\/J+-+ * ", d Glass temperatures _ center Figure 10 Room and glass temperatures: Test Time. min TOP J' _.-*-. _... _ Mid STD curve.._.-._.-.-._...* ,/ Bottom _c-- _--_, / Glass mparafures Upper AVG ,O Time, min Figure 11 Room and glass temperatures: Test 2-2.

15 Fire Tests on Window Assemblies ~oom temprstures 1 L _ _._ *-..-,..--- STD CUNC ' 1m.o Bottom A, : P (31- temperatures L w r AVG _LUEnvG-. - /-- _ L Z Time. min Figure 12 Room and glass temperatures: Test mo.o- - Room temperatures - STD curve U m. Gtass temperatures O Time, min Figure 13 Room and glass temperatures: Test 18.

16 126 Fire Technology ture in line with the standard curve during the latter part (approximately 20 min) of the tests, mainly because of the significantly lower temperature in the bottom of the room. To increase temperatures in the room so that they followed the standard curve, a sheet steel baffle, which directed more of the steam and water spray toward the exhaust stacks, was installed (see Figure 1). The significance on the fire exposure to the sample of locating the ther- 1 mocouples further away cannot be exactly determined. The thermocouple readings were representative of the air temperature adjacent to an envelope comprised of the water spray and the glass and not just the glass itself. t * must be appreciated, however, that the total heat input to the room (and the resulting fire exposure to the sample) was approximately 60% higher with sprinklers operating than without in order to compensate for the heat absorbed by the water spray. Approximately 20 min after the tests using sprinklers had begun, temperatures on the unexposed face of the glass reached a reasonably steady state. The average temperature on the lower half of the glass was approximately 30 C higher than on the upper half (see Figures 10 through 12). This is probably because the water absorbed heat as it ran down the glass. The temperatures on the outside of the double-glazed assembly (see Figure 11) were higher than the temperatures on the single-glazed units (see Figures 10 and 12), since the outer glazing was not receiving the cooling effects of the water from the sprinkler. n Tests 1-1, 1-2, and 1-3, water flow rates were varied to determine their effect on glass temperatures on the unexposed face. n these tests, the temperatures on the unexposed face rose when the water flow rate was less than 100 Llmin, and tended to stabilize between 65 C and 100 C at flows greater than 100 Llmin (see Figure 14). Temperatures at the center of the glass, in particular, tended to increase rapidly with decreases in the water flow rate, as shown by the Test 1-2 results in Figure 13. These results may be attributed to the fact that the greater portion of the discharge from the sprinkler was directed toward the side of the window, so that decreasing the flow prevented the water from reaching and cooling the center of the glass. n Tests 1-6 and 1-7, in which no sprinklers were used, temperatures of the unexposed glass were significantly higher than temperatures in tests using sprinklers at the same point in the test. n Test 1-6, average and max-.. imum temperatures for unexposed glass were 260 C and 290 C. respectively, when the glass broke at 6.5 min. At breakage, the temperature at the center of the exposed side of the glass was 380 C. n Test 1-7, the glass broke at 5 min when the average temperature was 240 C and the maximum temperature was 260 C. At breakage, the temperature on the lower half of the exposed side of the glass was 290 C. n Test 1-8, in which the sprinkler was located outside the burn room, temperatures of the unexposed side of the glass rose to approximately

17 Fire Tests on Window Assemblies C prior to sprinkler activation. Following sprinkler activation, the temperatures rapidly fell, so that the average of the five thermocouples on the unexposed face was less than 50 C. These thermocouples were exposed to the water flow from the sprinkler. FRAME TEMPERATURES n the steel frame tests in which sprinklers were located inside the burn J room (Tests 1-1 through 1-5), temperatures on the outside face of the frame were below 100 C when the water flow rate exceeded 100 Llmin (90 Llminlm). Temperatures as high as 170 C were recorded on the outer frame. when the water flow rate was 80 Llmin (72 Llminlm) or less. On the inner frame, temperatures less than 100 C were recorded, for the most part, when the water flow rate exceeded 100 Llmin; temperatures increased to 300 C when the water flow rate was reduced to 80 Llmin. The lower temperatures noted when the sprinklers were located on the fire-exposed side indicate that frame materials less heat resistant than steel can be used under such conditions. n Test 1-8, in which the sprinkler was outside the burn room, temperatures recorded on the fire-exposed side of the frame were 900 C to 1050 C, while the temperatures of the outer frame (in contact with the sprinkler spray) were 20 C to 60 C. f sprinklers are located on the unexposed side, steel is probably the only material that can withstand such temperatures without failing.! - 1 \ n Glass temperatures, m d ',._ ',. -,-.,*,,-.,-.--,,~,,.,'- -: #'/ - 'r,.,)' r,-',--' \ Center, /---w-~~,*-.%~, - /-J,-,,/ Flow rate l1terslm1n.l on 90 1, , lzo Tlme. min Figure 14 Glass temperatures and water flow rates: Test 1-2.

18 128 Fire Technology n the Series 2 tests, in which the aluminum frame was partly protected by gypsum board on the fire-exposed side, the temperatures of the inner frame (in contact with the water spray) ranged from approximately 20 C at the top to approximately 60 C at the bottom. The outer frame temperatures ranged from approximately 45 C at the top to approximately 70 C at the bottom. n both tests in this series, frame temperatures reached a steady state 20 min after the start of the test. n the Series 3 test, in which the aluminum frame was fully exposed to fire, the inner frame temperatures ranged from approximately 60 "C to 80" C on the sides and bottom to approximately 150 C at the top. Because of its location on the frame, the top inside thermocouple was not directly in the water spray, hence the higher temperature. The outer frame temperatures ranged from approximately 20 C at the top to approximately 70 C on the south side. During this test it was noted that the gasket material at the top of the window had developed a leak approximately 20 min after the test had begun, causing a water film to run down the center of the unexposed face. This resulted in the low temperatures of the unexposed side of the bottom frame member. The maximum radiant heat flux transmitted through the windows is given in Table 3. Radiometers were located either at the midpoint, or at the midpoint of the top or bottom half of the windows. n the 2-h tests, reasonably steady-state conditions were observed from approximately 60 min after the start of the test until the end. n Test 3-1, a leak developed in the gasket material at the top of the window near the centerline. A small amount of water flowed down the outside of the glass, reducing the radiation received by the radiometer. The radiant heat inside the burn room at the 2-h point in the fire test is calculated to be approximately 10 Wlcm2. The maximum radiant heat flux measured on the unexposed side of the glass in any test was 0.6 Wlcm2, indicating absorption greater than 90% by the water and the glass. This agrees with the results reported in the Australian tests." Law9 and McGuire'" have both reported that to ignite cellulosic materials (unpiloted ignition), a heat flux of 3.35 Wlcm2 (0.8 callcm21s) is required. The radiant heat flux on the unexposed side of the glass in the tests described here did not exceed 20% of this value. Law9 also reports that a person can tolerate a radiation intensity of 0.59 Wlcm2 for up to 10 s before - * he feels unbearable pain. This would mean that a person could take up to 10 s to move past a window in a compartment with a fully developed fire where sprinkler protection similar to that used in the tests is installed. The air pressure inside the burn room in all tests was positive (relative to atmospheric) from the beginning and increased to 25 Pa (above atmospheric) at the end of the 45-min test (Test 2-2) and 40 Pa at the end of

19 Fire Tests on Window Assemblies Table 3 Maximum radiant heat flux on unexposed side of glass. Test Maximum Radiant Number Heat Flux (W/cm2) 1-4 Top half 0.58 Bottom half Midpoint Midpoint 0.45' 1-8 Midpoint Midpoint Bottom half 0.47 ' Occurred at time of glass breakage (6.5 min). the 120-min tests. n Test 1-8, in which the sprinkler was outside the burn room, the air pressure progressively rose to a maximum of 35 Pa at the end of the 120-min test. The positive pressure was the result of supply air for the burner, steam generation, the exhaust configuration, exhaust flow resistance, and the buoyancy of hot gases inside the room. Sprinkler activation times are shown in Table 2. n all tests where tempered glass was used, the sprinklers inside the burn room activated early enough to prevent the glass from breaking. n general, the quickresponse sprinklers used in the Series 2 and 3 tests responded two to three times faster than the standard sprinklers in Tests 1-4 and 1-5. The fast activation times recorded in Table 2 for Tests 1-1 through 1-3 were due to a high initial gas input to the burn room, which resulted in a temperature rise more rapid than that specified by the standard time-temperature curve. When a quick-response sprinkler was placed outside the wired glass in Test 1-8, the response time was 315 s (see Figure 14). At this point in Test 1-8, temperatures for the unexposed glass were in the range where tempered glass failed in Tests 1-6 (average temperature 262 C) and 1-7 (average temperature 247 C). The wired glass, although cracked extensively, withstood the thermal shock following sprinkler activation. n Test 1-7, a 150 X 150 mm sheet steel baffle was placed outside the glass behind a quick-response sprinkler to form a trap for hot air rising along the pane. The sprinkler was not connected to the water supply. This reduced sprinkler activation time to, 270 s. Although use of a baffle was not investigated, it may ensure sprinkler activation early enough to prevent tempered glass from breaking. f so, then tempered-glass assemblies could be protected by sprinklers on the unexposed face... Sprinkler water flow rates and water flows per meter of glass pane width are shown in Table 2. n general, varying the water flow rates tended to affect the center of the glazing more than the edges and the frames, although minor variations in conditions at these locations were also noticed.

20 130 Fire Technology n the Series 1 tests, the water flow rate required to prevent dry spots from forming on the glass was 100 Llmin (90 Llmin per meter width) when the sprinkler was located inside the burn room. At this flow rate, steadystate conditions developed on the glass (the temperatures of the unexposed glass ranged from 65 C to 120 C) at approximately 20 min after the start of each test, as noted in Figure 10 for Test 1-5 (see also Figure 13 for Test 1-2). n Test 1-3 at a water flow rate of 110 Llmin (100 Llmin per meter width), : temperatures of the unexposed glass were in the range of 70 C to 110 C when steady-state conditions were reached. n Test 1-8, in which the sprinkler was located outside the burn room, the radiation transferred through the glass tended to increase when the water flow rate was reduced to 60 Llmin (55 Llmin per meter width) or lower. n this test, no significant increase in temperature on the unexposed face was noted with decreasing water flows. n the Series 2 tests, the water flow rate required to prevent dry spots on the inner glass surface was found to be 110 Llmin (74 Llmin per meter width). The thermocouples were located on the outside of the outer pane of the doubleglazed unit, and as such the temperatures of the unexposed glass did not show much variation with changing water flow rates on the exposed glass (inner pane). n the Series 3 test, it was found that the water flow rate required to keep dry spots from forming was 115 Llmin (68 Llmin per meter width). With lower flows, dry spots were observed on the center portion of the exposed side of the glass. Following Test 3-1, the unexposed face of the tempered-glass assembly was subjected to a nonstandard hose-stream test, as described previously. t differed from the standard tests due to the fact that the standard hosestream test equipment was not available and that the test wall could not be removed from the test apparatus to enable the exposed sample face to be subjected to the hose stream. While the flow rate of the nozzle used (473 Llmin) was less than that required in the standard (784 Llmin), the increased velocity due to the increased nozzle pressure (690 kpa versus 205 kpa) gave a momentum that is approximately the same as the standard hose stream. The tempered glass did not break, and no damage was caused to the frame as a result of the described hose-stream test. Since the glass tempera- - 1 tures in all tests were low, it is anticipated that any wired- or temperedglass assembly protected by sprinklers on the fire-exposed face, as described, could survive the standard hose-stream test. During the tests in which the sprinklers were inside the burn room, a greater-than-expected quantity of fuel was needed to maintain the standard time-temperature curve. Assuming 100% combustion efficiency, the

21 Fire Tests on Window Assemblies 131 estimated heat-release rate when the sprinkler was inside the burn room was approximately 4 MW during the last minutes of the 2-h tests. When the sprinkler was outside the burn room, the estimated heat release rate during the last minutes of the 2-h test was approximately 2.5 MW. CONCLUSONS From these series of experiments, the following conclusions were drawn. ' These conclusions relate to the glazing systems and sprinkler arrangements tested and should not be construed as being representative of other situations, unless noted.. 1. The glazed assemblies protected by sprinklers, as described, will withstand a fire exposure approximating that provided by the standard time-temperature exposure; for at least 2 h for single-glazed assemblies, and at least 90 min for double-glazed assemblies. Since the assemblies did not fail at those times, durations greater than those tested can realistically be expected. 2. The level of radiation transmitted through the protected glazed assemblies is not sufficient to ignite (unpiloted ignition) ordinary combustible materials adjacent to the unexposed side, or to cause unbearable pain to a person moving past the window in less than 10 s. 3. The temperatures measured on the unexposed face of assemblies in which sprinklers were located on the fireexposed side are within the range permitted by CAN4-S The glazed assemblies, as described, cooled by sprinklers on the fireexposed side, can withstand a nonstandard hosestream test following fire exposure. 5. When sprinklers are installed on the fire-exposed side, both quickresponse and standard sprinklers respond in sufficient time to prevent tempered glass from breaking when the sprinkler is activated. n the case of sprinklers installed on the unexposed face, it is not known whether even quick-response sprinklers can activate quickly enough to prevent tempered glass from breaking upon sprinkler activation, unless other means are provided to reduce sprinkler response time. 6. Wired glazed assemblies in steel frames can withstand the described ;. fire exposure for at least 2 h, whether sprinklers are installed on the fire-exposed or unexposed side. 7. Minimum sprinkler water flow rates to prevent dry spots from form- - ' ing on the glass appear to be 70 to 80 Llmin per meter width, but lower flow rates may provide sufficient protection. 8. Sprinkler water distribution to the center portion of the glass appears to be at least as critical as distribution to the sides to prevent dry spots from occurring. 9. The heat input required to maintain the standard timetemperature curve in the burn room (measured 1.4 m from the sample) when a

22 Fire Technology sprinkler is located on the fire-exposed side, as described, is approximately 60% greater than when a sprinkler is located outside the burn room. 10. Aluminum and steel frame materials behave similarly (with respect to warping and distortion) when sprinklers are located on the fire exposed side. t 11. Tempered-glass assemblies with areas greater than 5 times and dimensions greater than 1.8 times the wired-glass specifications in the National Building Code of Canada are able to withstand a fire exposure approximating the standard fire exposure for at least 2 h? when sprinklers are located on the fire-exposed side, as described. 12. Radiated heat flux levels are reduced by more than 90% by the window sprinkler systems used in these tests. As with all fire protection measures, the designer must realize the limitations of this protection system to ensure its proper use. One system under specified conditions has been described. Details such as pane size, location and response time of sprinklers, water flow rates, frame materials and mounting techniques, and water distribution over the glass have been identified as most important factors and must be carefully assessed prior to utilizing a window sprinkler system. ACKNOWLEDGEMENTS: The authors wish to thank Rolf Jensen and Associates Ltd. for their permission to use the information gathered from tests performed under contract to them, and Grinnell Fire Protection Systems Co. Ltd. for providing the sprinkler installations. The authors appreciate the assistance of J. E. Berndt, D. W. Carpenter, G. P. Crampton, V. Fortington, and M. Ryan at the National Fire Laboratory in the design, installation, execution and analysis of these tests. REFERENCES ' The National Building Code of Canada. Associate Committee on the National Building Code, National Research Council of Canada, Ottawa "Fire-Resisting Glazing - Clear Borosilicate Glass," FPA nformation Sheet B17, Fire Protection Association, London. January ' Malcomson, R. W., "Report on Window Sprinkler Systems," Underwriters Laboratories nc., Report No. NC529, Northbrook, L. July ' Moulen, A. W. and Grubits, S. J.. "Water Curtains to Shield Glass from Radiant Heat from Building Fires," Technical Record , Experimental Building Station, Department of Housing and Construction. Australia, July ' Moulen, A. W. and Grubits. S. J., "Water Drenching of Tempered Glass Used to At- -' tenuate Radiant Heat," Technical Record 498, Experimental Building Station, Department of Housing and Constuction, Australia, July "erguson, A,. "New Standards for Atrium Building," Fire Prevention, No. 184, London, November ' Deutsches nstitut fiir Normung Report 4102, Part 3, "Fire Behavior of Building Materials -and Building Components; Fire Walls and Non Load Bearing External Walls; Definitions, Requirements and Tests." Deutsches nstitut fiir Normung, Standard Methods of Fire Endurance Tests of Building Construction and Materials (CAN4-S101-M82), Underwriters' Laboratories of Canada, Toronto, December Law, M., "Safe Distances from Wired Glass Screening a Fire,".F.E. Quarterly. Vol. 29, No. 73, March 1969, pp '" McGuire, J. H., "gnition of Materials behind Common 118-inch Thick Window Glass," Technical Note 456, Division of Building Research, National Research Council of Canada, Ottawa, September 1965.

23 This paper is being distributed in reprint form by the nstitute for Research in Construction. A list of building practice and research publications available from the nstitute may be obtained by writing to the Publications Section, nstitute for Research in Construction, National Research Council of Canada, Ottawa, Ontario, K1A 0R6. Ce document est distribu6 sous forme de tire-3-part par l11nstitut de recherche en construction. On peut obtenir une liste des publications de 1'nstitut portant sur les techniques ou les recherches en matisre de bltiment en Ccrivant a la Section des publications, ns ti tut de recherche en construction, Conseil national de recherches du Canada, Ottawa (Ontario), K1A OR6.