An Improved Automatic Dry Pipe Sprinkler System.
The recent destructive fires in the business district of Boston have stimulated to an unusual extent interest in the discussion of the merits and demerits of automatic sprinklers for the protection of business structures, and our readers will doubtless feel interested in the accompanying illustrations and description of a newly designed automatic dry pipe system, for which several improvements in details and working are claimed. The device is ingenious and deserves close investigation.
The construction and arrangement of the parts are illustrated in the cuts. A represents the tank, B the main riser, with its several services, branches I, I, and the sprinkler heads 2, 2, gate C and check valves, D.
The new and distinctive features are embodied in the additions and use of the S trap, I, represented on an enlarged scale in fig. I; the recharging air-chamber H and seal chamber L. In this the main riser B and the supplementary riser F, terminate, the latter provided with valve g, drain pipe and valves 3, 3, Further, the pneumatic service pipes, 6, 6, and their respective gong alarm actuating device, N, N, the latter represented in an enlarged scale in fig. 2. These, with their several minor details, constitute the improvements, all of which, in describing their operations, will be more closely represented.
Assuming that a fire has just occurred, and the system is to be readjusted for the next emergency, the gate valve C is closed, the pet or air cock p on the crown of trap S is opened, and valve g on the supplementary riser F is closed. The system is then drained with valve 3, also chamber 11, the tank A being refilled by pump E and riser R. The drainage completed and sprinkler heads readjusted, the air cock p and all drain connections are closed. This being done, with pump E, or by the street main, water is then forced into the chamber H, expelling the air from it through the check P into the system.
If one pulsation or charge of the tank II fails to create the desired air pressure in the system, the water may be drained again from H, allowing another charge of air to enter through the reverse check valve of thus repeating the pulsations until a pressure is secured in riser B and its connections, equal to or greater than that due to the column of water resting above the seal line, x,x, in trap I. Gauge 9 will indicate when this point is reached, at which the equalizing valve g on chamber L is opened, allowing the pre-existing column of water in F, which being equal to or greater than that existing above the seal in trap I, maintaining an equilibrium, and holds the water back, as shown in fig. 1, until such time as a fire opens one or more of the heads 2, 2. Through these the air escapes and the water responds as ordinarily with the advantages due to not having to move valves and kindred obstructions.
Another advantage with which this system is credited lies in the impossibility of the whole organization becoming disarranged by slight leaks, from the fact that what water passes over the seal x, x, owing to a reduction of air pressure, will establish its necessary equilibrium by rising in F. The position .of the water is indicated on the glass water gauge 8.
In responding to a fire the pressure in F is equal to the column of water due to height from chamber L to the level in the tank; advantage of which is taken in utilizing the pre-existing air above the water in F, and in the pneumatic connections 6, 6, in forcing this air into the flexible hooded chamber valve N, as shown in Fig. 2 the stem v, being connected to alarm mechanism. After the alarm is set going no more air can escape, the valve W being held firmly to its seat.
It is evident in this that the two most essential features arc secured in the dry pipe system; a quick and unobstructed response from the water and immediate alarms, without the use of electrical, or easily derailed mechanical appliances. Where electrical appliances are preferred to the pneumatic system, the pipe h can be continued and connected with the tank or riser above the gate valve, thereby securing the advantage due to a surplus pressure acting against the valve D over what is required to hold the water at x, x, thereby insuring a larger margin against air leakage from the system.
Further information concerning this new system may be had from the designer, Beter Smith of No. 222 Fifth avenue, New York.