Modern Fire Alarm Signalling
Planning an Industrial Fire Alarm Installation—Box Locations and Numbers
THIS, the twenty-third article on fire alarm subjects, concludes the series of articles by Mr. Kcirstead on “Modern Fire Alarm Signalling.”
Protection for Small Plants:
Every small establishment should have at least one standard type municipal box installed on their premises, as near to the main gate or entrance as is possible. This box should be connected to the city or town alarm system. This box should be assigned a special number to denote its location, and while it will have to be purchased by the firm owning the factory or building it should be maintained by the city fire alarm department and not by the companies employers.
The private box protection can be increased by the uses of auxiliary pull stations which may be located on each floor. The pulling of this box will set the master box in operation and the alarm will be sent through to headquarters without leaving the building. Thus with a multiplicity of auxiliary boxes it is possible to send alarms from several points.
There are two systems which may be used to a good advantage in large and small plants, situated in the department service area: a system which will call the outside department whenever a box is pulled in the plant; a system which will call out the factory brigade when a box is pulled, leaving the calling of the cities forces to the plant fire chief through a manual means of operation.
With the first, it is simply necessary to pull the box in the building and then instruct the fire department as to the location of the fire upon their arrival.
In the other plan a city box is installed at the main gate, power house or office, where a watchman or engineer is constantly on duty. The watchman is instructed to await orders when an alarm is received over the plant system. There will be at least one city box installed at this point and upon the orders of the plant chief, the city box will be pulled, and the department directed to the scene of the fire. Where there are several entrances at the plant, it is well to have a box for each gate and have special numbers given to each box.
Where a plant is located away from the city department the latter system may be used to advantage, as it will be possible to organize a plant brigade, and provide for drills and tests to be made at intervals. Where this system is used the city box is to be used for alarm service only. The boxes used should be of the non-interfering type and be numbered properly in order to get the best possible use from them.
Type of Boxes, Location and Numbering:
When planning a layout for a system use enough boxes so that the floor area to be covered will not make it necessary to travel more than three hundred feet in any direction to reach a box. Have a box at each stair way or entrance, and have them placed so that it will not be necessary to travel away from a natural exit to reach a box. It will fee necessary to take into consideration any special hazards that may exist. Have the boxes standard in their location, that is, in tfee same position on all floors, and have a list of the boxes posted over every box.
Care should be taken at all times to have the approach to a box clear of all obstructions and a red light should be provided at the location at night. Large plants should be well supplied with boxes and special attention should be given to railroad tracks, bridges, etc., to see that it will be possible to reach the box if the way is blocked by a train or the bridge is removed.
Boxes should be numbered according to floors and direction. For example with three number boxes, the first number is the location of the box. such as wing number, plant number or storehouse number. Where there are seven buildings in the property, allow the first number for each one of the buildings. The second number should be allotted to floor on which the box is located. The last or remaining number can be given as the box number. For instance box number 374 would be interpreted as a box located in building three and located on the seventh floor. In figure No. 63 is a type of industrial box.
Gongs and Sounding Devices:
The best type of gong to use in an industrial installation are electro-mechanical gongs. These gongs are placed directly in the box circuit, and are operated by the box itself. The only objection to these gongs is that they will have to lxkept wound up at all times. They should be of a size large enougfe to give a good clear signal above all other noise. They should if possible be located directly over the alarm boxes.
The best type of gong to use is the turtle gong illustrated in Figure No. 64. It may be mounted on the wall or on a panel, and special care must be taken to make sure that the binding posts are upright as this gong depends upon gravity action to drop the hammer.
Switchboards and Battery Energy:
In all types of fire alarm work it is necessary to use duplicates sets of batteries—it is also true in industrial work. One set is charged on the working side of twenty-four hours and then the other Sank or side is shifted into its place.
To control the system a storage battery controlling switchboard is used. It is equipped with the necessary switches, etc., for charging and controlling the batteries. These boards are made up in, one-, two-, four-, six and ten-circuit capacity. It is only possible to place twelve boxes on any one circuit, so if you have forty-eight boxes it will be necessary for you to get a four circuit board. There were two articles given on storage battery switchboards and it will be well to refer to them as much as possible when planning any type of industrial installation.
If the factory has not direct current available, it will be necessary to have a motor generator set to charge the batteries. The size of the generator can be obtained by refering to article No. 23.
F. I. P. batteries are the best type to use as they were especially designed for fire alarm signal work and will give excellent service with a minimum amount of attention. Their capacity is 6-ampere hours and they are discharged at the rate of 1/10-ampere an hour. In twenty-four hours the rate of discharge will be 2.4 amperes.
It is a simple matter of wiring to obtain the following results when a box is pulled for fire.
Call the public fire department.
Call the plant brigade to the location of the fire.
Sound the signal only in the building or place afire.
Sound the signal throughout all buildings and call the plant and city department.
The wiring plan may be arranged so that a drill may lx* had in any building at will, without calling the plant or city department.
Where building or floor drills are held, it is very important that the system be SO arranged that if a box is pulled for an actual fire the drill feature will be automatically cut out and the alarm sent through. This is necessary in order to avoid confusion and delay.
When planning any installation it would be a good move on your part to call in the local alarm superintendent as he will no doubt be able to give you the benefit of his knowledge. He will be able, from past experience to offer many suggestions.
New Station Opened in Birmingham, Ala.—-The first of the five new fire stations which are being built in Birmingham, Ala., has been officially placed in service.