COTTON WAREHOUSE CONSTRUCTION. 35 
Description of a modern automatic sprinkler system.—The direct out- 
growth of this crude arrangement was the present automatic sprinkler 
system. This system consists of a tank or other means of supplying 
water. Ordinarily it is a large gravity tank and has direct connec- 
tion with at least one city main. Pipes connecting with this main 
are in all portions of the building. The water is distributed by 
sprinkler heads. These heads are so arranged that when they are 
heated to a certain degree they open and send out a considerable 
stream or spray of water Under good pressure one head will dis- 
charge some 40 or 50 gallons of water per minute. This system has 
two very important advantages over the earlier form. The water is 
liberated automatically—that is, when a fire starts the heat opens 
the heads and the water is turned on without the attention of any 
person. A second advantage is that only those heads near the fire 
are opened. This prevents damage to wares in other portions of 
the compartment and also conserves the water except for the par- 
ticular space where the fire is burning. 
The automatic sprinkler system in its latest development consists 
of a tank or other water supply of ample capacity—depending upon 
the amount of space protected by the system—proper connections 
with the city mains or other sources of water, sprinkler heads distri- 
buted over the building with the necessary water supply pipes, and an 
alarm which is set off automatically when a fire starts. If a dry-pipe 
system is used, in order to prevent freezing of the water in the pipe, 
the system requires draining after a fire, and the dry-pipe: valve 1s 
then reset. The water pressure at the heads should be at least 15 
pounds, which makes it necessary for the tank to be at least 30 feet 
above the highest head. A dry valve is not always used, except 
where there is danger that water will freeze in the pipes, and thus 
render the system worthless at a time when it might be needed. 
When it is possible, the system should have at least a 6-inch con- 
nection with the city main. The sprinkler heads should be distrib- 
uted over the building in such a way that one head would cover a 
space of 65 to 90 square feet, depending upon the arrangement and 
construction of the building. These heads should be placed near 
the ceiling. If a fire occurs near the floor, the heat rises immediately, 
and the heads directly over the fire are opened automatically. It 
requires 155° to 165° IF. to melt the solder and automatically release 
the water. 
A fully protected warehouse which conforms in every respect to 
the requirements of the underwriters’ association is shown in figure 
13. When cotton is valued at 10 cents per pound, or $50 per bale, 
it is possible to insure it in this warehouse at the rate of 5 cents per 
bale per annum. ‘This illustrates forcibly the advantage to be gained 
by conforming to the underwriters’ standards and installing approved 
