Water Fog Impressive in Class “A” Fire Tests
Cooperatively Conducted Dwelling Fire Tests Provide New Evidence on Use of Water Fog
A STAFF REPORT
WHAT are considered the first largescale comprehensive field tests the use of water-fog in fighting Class A dwelling fires were held at Hamden, Conn., October 11, under the sponsorship of the Hamden Fire Department, Chief R. C. Spencer; New Haven Fire Department, Chief Paul P. Heinz, and the Rockwood Sprinkler Company. A crowd of several hundred visiting chiefs, municipal officials and others observed the experiments.
For the tests, a condemned two-anda-half story frame dwelling on the outskirts of Hamden was secured. Although beyond the city’s water supply system, ample water was provided by a nearby stream from which pumpers of the Hamden department delivered water for the tests, and to protect exposures. Ladder Co. No. 3 of the New Haven Fire Department was also used.
All-told there were five tests conducted during the progressive burning of the frame clapboard structure,* as follows:
TEST NO. 1; Object: to extinguish a cellar fire by advancing line through heat and smoke down basement stairs behind water fog nozzle.
For this test a large quantity of waste wood was piled in the front part of the cellar. Stairway was not obstructed. 5 gals, of solvents; 1-gal. of motor oil; 1 of kerosene and 3 of gasoline were used as primer. Fire was ignited by torch tossed through basement windows after gasoline had been applied.
After about 2-min. pre-burn, a 1 1/2-in. line with 1-in. fog nozzle was advanced down stairway by two men. The waterfog discharge proved insufficient and 30-sec. later shift was made to a 1 1/2-in. water fog nozzle, extinguishing the major part of fire in 2-min. and complete extinguishment 1 min. later. The 1-in. fog-nozzle followed the 1 1/2-in. downstairs and assisted in final overhaul.
One-inch nozzle used 3 min. at 50 PSI delivering 12 GPM, total 36 gal.:1 1/2-in. nozzle used 2 min. 30 sec., at 100 PSI delivery 55 GPM. for Total of 158 gals. Total water used 174 gals., approximately.
•With the exception of the improvised cellarpipe (built by the New Haven Fire Department) all nozzles used were Rockwood type.
Firemen on line reported that the 1 1/2-in. nozzle was entirely adequate, and that they felt no heat when advancing down cellar stairway.
Examination showed the stairway heavily charred, joists in cellar lightly charred and 1/4-in. depth of char noticed in various places. Sonic small pieces ot waste wood had been completely consumed. There was little or no loose water on floor.
Test indicated conclusively the advantage of water fog in attacking a hot basement fire by way of cellar stairway—usually a punishing operation for firemen.
TEST NO. 2: To extinguish large cellar fire by means of cellar-pipe applied through hole in first floor.
Another large quantity of flammable material was piled in center of cellar under the floor opening and primed with 5 gal. each of gasoline and solvents. After 2-min. pre-burn firemen operated cellar pipe (constructed of four old OCD type “fog” nozzles brazed on a 2 1/2-in. metal pipe) supplied by 200-ft. 2 1/2-in. line. Discharge was approx. 440 gpm in the 45-sec. the pipe was operated. Pump pressure was 200 psi. Total discharge approx. 330 gals. Final glowing embers extinguished with 1 1/2-in. line.
TEST No. 3: Object to extinguish large fire within a house by means of waterfog (including fire on two floors, behind partitions and walls, and in blind attic).
Considerable combustible material was piled into center of room on first floor; plaster and lath was removed above pipe to allow fire to travel between studding to second floor. Excelsior was placed in second-floor room and in attic, which opened into rear second floor room through a 14-in. x 30-in. trap-door. This was left open. Attic was also vented by front and rear windows and by hole in ceiling of second-floor front room; no stops in partitions. An area about 6-sq. ft. was opened in rear partition of first floor center room and the ceiling was also opened to further the fire, which was started on the first floor after priming with 5-gals, each of gasoline and solvents.
Thirty seconds alter ignition all of the first and part of second floors were involved; flames were sweeping out of windows of both floors and outside claphoards were burning.
hire was fought with two 1 1/2-in. and one 1-in. water fog nozzles. Pressures at nozzles approx. 100 psi. One line advanced through front door, straight through downstairs; one up stairway to second floor; third line (1-in. nozzle) hacked up one on the gound floor.
Water fog first applied to fire 1 min. 16 sec. after start. In 17 sec., fire in the first floor was practically out. Fire was extinguished in second floor and attic 1 min. and 4 sec. after start of operations. The three inside lines wen then used to extinguish glowing embers and all water was shut off 3 min., 14 sec. after start of attack.
It was noted that when water fog was applied to main fire (first floor) there was an almost instantaneous quenching effect, and the fire on outside of house, fed by flames lapping out of first floor windows, immediately died down, leaving a charred surface.
It was also observed that a hot fire in an alcove on the main floor was apparently extinguished by the indirect application of the water fog pattern passing through an adjoining room— not by any direct application in the alcove itself. This was evidently due to convection currents, which apparently pulled the fire out of the small room and from the window out of which it was “emitting.” The room was later completely cooled with a quick dash of water fog.
The men operating the lines experienced no difficulty in advancing. The discharge rate of water fog at 100 psi was 126 gpm. Total discharge of water for all operations inside of house was 416 gals.
Here is the time schedule for this test:
TEST NO. 4: To extinguish fire by means of large water fog nozzle mounted on aerial ladder.
For this test the attic (described in Test No. 3) was loaded with combustible material; rear window was boarded to restrict draft, and fire in attic space was lighted. Here is the chronological sequence:
This fire burned sluggishly, due to lack of ventilation in attic. As window blocking was removed, the fire increased in intensity. While fire was progressing. water fog nozzle was discharging harmlessly in the direction away from the fire itself. At given signal, the aerial ladder, partly extended, was swung so that the fog nozzle passed across front attic window, horizontally. It was allowed to remain, discharging into the window (most of the pattern was effective in penetration) for 2 sec. and then removed by rotating the ladder turntable and depressing the fog stream by means of guide-lines.
When the water fog was applied to window, a large quantity of smoke and steam emitted from rear attic window. The 2 1/2-in. nozzle used for this test discharged about 201) gpm at 100 psi. Approx. 7 gals, of water were used to knock out this fire.
TEST NO. 5: To apply a large volume of water fog to a fire completely involving a house in effort to fully control fire (an agreement had previously been made that house was to be completely burned at finish of test. Because of this there was no intention of completely extinguishing all fire since it would be difficult to rekindle and reburn it).
For this test a relatively large quantity of waste combustible material was placed throughout the house and primed with oil and gasoline on the first floor. Due to wet conditions the fire was slow in gaining headway. Clapboards and some partitions were removed or pierced to hasten burning.
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Twenty-two minutes after ignition the fire was going well and the entire house practically involved. Ladder with fog nozzle (used in preceding test) was extended and. 28-min. after start of the fire, water was applied at 100 psi. the ladder being swung over the top of the house with the nozzle pointing almost downward, for a period of 40-sec. In this brief time it was demonstrated conclusively that the discharge would easily control a larger fire than this dwelling if sufficient fog volume was applied.
In the 40 sec., the fire decreased from maximum intensity to very low burning rate and extinguishment would have occurred it water fog discharge had not been stopped. All vertical heat radiation and sparks almost immediately ceased.
The fire was then permitted to rekindle and the house burned to the foundation.
Detailed operations of preparing the structure, ignition, fighting the fire and dccribing operations were directed by Chiefs Spencer and Heinz, and his assistant. Deputy Chief Collins, officers and members of both departments, and Mr. James Ryan, assisted by engineering representatives of the Rockwood Sprinkler Company.