What should be the spacing of the ¾-inch round wrought-iron hoops on a tank 10 feet in diameter and 12 feet high at a distance of 6 feet from the water-line?
Ans. 12 in.
73. Automatic Sprinkler System.—The sprinkler system as now installed for protection against fire in the interior of a building consists essentially of piping connected to a gravity tank and extending over the entire ceiling by means of mains and branches. There is located on the ends of the branches automatic valves or stops, which are collapsed or opened by the melting of a fuse or solder at a temperature more than is likely to exist in the room at any time and still below that which would be created by an incipient fire.
74. The underlying principles of automatic sprinkler systems as stated by the Underwriters are as follows:
1. Buildings must be open in construction, free from concealed spaces, or places where water thrown from sprinklers cannot penetrate.
2. Sprinklers to be so located that their distribution will cover all parts of the premises.
3. Sprinkler piping to be of sufficient capacity and to have water under pressure in same at all times, except in case of a system where freezing is likely to occur, where an air lock is used.
4. An automatic supply of water of sufficient quantity and pressure available at all times.
5. Systematic, thorough, and intelligent care and inspection of the system.
75. Fireproof Windows.—It is frequently necessary, and in many cases required by law, and especially recommended by the Underwriters, to provide fireproof window frames and sash in walls exposed to great fire risk, or where it is necessary to admit light into elevator shafts or fire-towers. To meet this demand, several forms of metallic window frames and sashes have been evolved, and these sashes when intended as a fire-retarder are always glazed with wired glass.