ATM FIRE ALARM SYSTEMS
|TAKEN FROM THE ATM FIRE ALARM APPARATUS CATALOGUE No. 84, 1929
In the protection of life and property from fire, speed is the first essential. Time is fire’s greatest ally, and from the start of a conflagration seconds count.
It is of little use spending large sums on fire-fighting appliances and the training and maintenance of an efficient personnel for dealing immediately with outbreaks, if the essential link - a ready means of signalling the fact is missing.
Every populous centre today has its Fire Station or Stations and its trained Brigade, either professional or voluntary.
The Fire Station may be at any convenient central point or points, and the Brigade ever ready, day or night, to respond to a call.
It remains to provide an efficient, reliable, and convenient means, established at frequent intervals throughout the area to be protected, whereby any member of the public can communicate promptly and easily with the nearest Fire Station.
THE CHOICE OF A FIRE ALARM SYSTEM
Fire Alarm Systems already in operation may be classified under two heads, according to their fundamental electrical principle, viz., “closed circuit” and “open circuit.”
The former is always under current, ever active, and therefore self-recording in the event of failure at any point. The latter is inert until an alarm is given, and therefore there is no indication of latent defects which may prevent the signal reaching the fire station.
Even when tested daily, and systematically, there is no guarantee that an “open circuit” Fire Alarm System will function at the psychological moment of an outbreak, when its services are most urgently required.
The weakest links in a Fire Alarm System are the lines connecting the Street Boxes with each other and with the recording apparatus at the Fire Station.
The lines comprising Fire Alarm Circuits are subject to three kinds of derangement: they may break, become earthed, or a portion may become short-circuited. Such contingencies are commonplace, especially with exposed lines, and cannot be foreseen.
The “ closed circuit” Fire Alarm principle lends itself admirably to the automatic and instantaneous recording of such contretemps as “line breaks” or “earths” immediately they occur, thus guaranteeing the reliability of the system in any emergency. Open circuit Fire Alarm Systems lack this invaluable characteristic.
Another important advantage of closed circuit working is economy in line plant, due to the accepted practice of including in series in each line “loop” a number of Street Boxes.
This reduces the cost of line plant to a minimum, a considerable advantage where lines are rented from the Post Office or other authority.
THE BEASLEY-GAMEWELL "CLOSED CIRCUIT" CODE SIGNALLING FIRE ALARM SYSTEM
The Street Fire Alarm Boxes are painted the conspicuous red colour associated with the Services, so that residents soon become familiar with their locations.
Psychology shows that in course of time the existence of these red boxes at various convenient points in an area becomes as familiar to the public as that of the ubiquitous red pillar boxes of the Post Office service, and in case of emergency a mental process automatically registers the location of the nearest and most convenient alarm box.
Associated with these Street Fire Alarm Boxes, but located at the Fire Station, is the Alarm and Recording Apparatus, which not
only gives audible warning of any call sent in from one or other of the Street Boxes but also registers permanently, by punching
in a moving paper tape, the code number of the box from which the alarm has been transmitted and printing the exact time and date
of the occurrence, thus placing this frequently debatable subject beyond dispute and effectually protecting the Brigade from false
charges of negligence.
The exact location of every box being on permanent and convenient record at the Fire Station, no time is lost in turning out and proceeding to the particular box indicated and thence to the scene of the fire, which, due to the general disposition of the boxes, will never be far removed from the point of origin of the alarm.
As previously intimated, the accepted practice in “closed circuit” working is to connect a number of these Street Fire Alarm Boxes in simple series on a loop circuit serving a district and terminating on the alarm and recording apparatus at the Fire Station.
In large city networks, embracing a considerable number of loops, and a multiplicity of boxes on each loop, there is a possibility of the simultaneous operation of two or more boxes on one loop, and this contingency must be safeguarded to ensure all signals, from whatever box, reaching the Fire Station without mutilation.
In comparatively small installations this is a matter of lesser moment, due to the extreme improbability of two boxes on the same loop circuit being operated simultaneously.
To cater for these alternative requirements the Beasley-Gamewell System employs three types of Street Fire Alarm Box:-
(1) The Positive Non-interfering Succession Box;
(2) The Non-interfering Sector Box.
(3) The Plain Sector Box.
The Positive Non-interfering Succession Box is capable of thirty-six repetitions of the signals on a full wind, and, normally, without further winding will send nine distinct alarms, each alarm comprising four repeat signals. In the event of other boxes on the same loop being operated simultaneously, one of the boxes will control the circuit to the Fire Station pending the completion of the four signals, when the next operated box will seize the connection and transmit its four signals in turn. In these circumstances, the Non-interfering Succession Boxes are capable of sending sixteen repeat signals, and each box operated will challenge the loop and cut itself in circuit at the beginning of any series of four signals should the line be free to receive them. Having once seized the line and transmitted its call, the box immediately comes to rest in readiness for the next alarm.
The Non-interfering Sector Box sends out four complete signals when its lever is fully depressed, and also provides that no mutilation of a fire call takes place when two or more boxes are operated simultaneously, but, unlike the Succession Box, the calls other than that registered are not stored for subsequent recording.
The Plain Sector Box resembles the Non-interfering type in all details except that signals from this box are subject to mutilation in the unlikely event (in small systems) of another Sector Box on the same loop being operated simultaneously.
All types of box are equipped with spring-driven mechanism for sending out the codes of electrical impulses which operate the recorder at the Fire Station, but whereas the Sector Boxes have an operating lever which, when manipulated by the person giving the alarm, winds up the driving spring, the springs of Non-interfering Succession Boxes are wound by the Fire Brigade staff, and operation of the box to send an alarm merely releases the clockwork train.
The underlying principle of each type of box is mechanical operation. This implies robust, spring-driven mechanism which can be relied upon to transmit firm, distinctive signals.
The signalling mechanism of each box is protected by three separate and distinct casings, affording ample weather safeguards and excluding dust and dirt from the contact surfaces, which are of pure platinum and of ample cross section.
Each box is equipped with all the usual testing and earthing keys, plugs, etc., and is adequately protected against lightning. A telephone jack is provided for the use of firemen, which permits of conversation with the Fire Station by means of a portable hand telephone. Alternatively, a hand telephone is provided in each box, and is accessible for police or ambulance calls.
The Alarm Boxes are suitable for mounting on cast-iron pedestals, or may be conveniently attached to walls, lamp or tramway standards.
Whichever type of box may be selected, the Beasley-Gamewell System is positive and self-testing at all times. Forming part of a closed electrical circuit to the Fire Station, a small current is always flowing through the loop and controlling alarm devices at the station, which operate immediately in the event of a line break at any point on the system.
There is thus never any doubt at Fire Brigade headquarters as to the condition of the entire system at any time of the day or night, and even a line break can be temporarily circumvented by throwing a switch at the Fire Station, which enables the boxes on the broken loop to continue functioning until repairs can be effected.
If lines come in contact with posts, etc., and cause earth faults. the system is unaffected and signals are received with the
same speed and accuracy as before. Earth faults are detected by daily routine tests and may be cleared at any favourable
opportunity, or the system may be provided with an earth test relay which gives an alarm immediately should a serious earth fault
occur. The apparatus for controlling lines is shown pictured to the right.
When operated, a Beasley-Gamewell Street Fire Alarm Box momentarily breaks or interrupts the normally closed circuit to the recorder at the Fire Station a definite number of times and in regular sequence, corresponding with the code number of the box itself.
The effect of these breaks or interruptions in the otherwise closed circuit on the Fire Station apparatus is four-fold.
An electro-mechanical gong responds with one stroke for each break, and simultaneously a hole is punched in a travelling paper tape, permanently recording the signal. Upon the completion of the call, a time and date stamp records upon the tape the exact time at which the call is received, together with the date, in the following order:-Year, month, day, hour, minute, a.m. or p.m.
The Recorder Tape is one inch wide with 1/4 inch diameter holes, thus affording a distinctive record of the call received.
During the foregoing cycle of operations a trembler alarm bell rings continuously.
Experienced firemen on duty hear the strokes of the gong, indicating the number of the box which is transmitting; confirmation of that number appears on the tape in a series of perforations, so that both ear and eye, attuned to promptitude in emergency, receive their messages simultaneously, and no time is lost in turning out.
The trembler alarm bell, which is also employed in association with the telephone facilities provided for firemen’s use, will continue to ring until released by the operation of a key. Should the Fire Station be unattended for any reason at the time a fire call is transmitted, the alarm bell will draw attention to this fact, and the code number of the box which sent the alarm can be immediately ascertained from the permanently recorded signal upon the paper tape.
SUB-STATIONS AND REPEATERS
As the above apparatus is similar to that already described for the Central Station, calls will be simultaneously recorded at both stations, thereby eliminating any delay that might be caused in communication between the two stations.
Some areas may have several sub-stations to which it is desirable that all calls be repeated. To meet this contingency a Repeater is used. This piece of apparatus first selects the loop from which a call is being transmitted, and then repeats that particular call simultaneously to all other loops and also to the gong and punching register of the Central Station; thus all the sub-stations are simultaneously warned for each call.
Further, with multi-circuit systems where there is separate recording apparatus for each circuit, there is a possibility of confusion of the audible signals should two calls be received at the same time from different loops. The installation of a repeater safeguards this contingency, and also obviates the necessity for multiple recording apparatus.
The Beasley-Gamewell Closed Circuit Code Signalling Fire Alarm System represents the accumulated experience and development of seventy years’ close study of fire alarm principles the world over.
The following list of existing installations affords proof of an established reputation:-
A auxiliary box to operate at a distance a street call box on the main system. Shown pictured to the right.
Police telephone facilities may be provided by means of a special box containing a telephone, which is usually mounted back to back with the Fire Alarm Box.
These telephones may be accessible to the police, only by the use of a key, or may alternatively be provided with a “Break Glass” Quick Action Door for the use of the public.
Factories, hospitals, schools, theatres, or other large and important buildings within the area served may be inter-connected with the Public Fire Alarm Service by means of an auxiliary system of simple Alarm Boxes.
For unattended Fire Stations a motor-driven siren can be provided which automatically comes into operation when a fire call is transmitted from an Alarm Box. These sirens have a range of audibility up to four miles.
THE A.T.M. LOUD-SPEAKING TELEPHONE FIRE ALARM SYSTEM
Like that system, our Loud-speaking Telephone Fire Alarm System has an ample margin of safety.
It comprises a number of Street Boxes, each connected to a central switchboard at the Fire Station by a single-line wire, the return circuit being via earth or a line wire common to all boxes.
The boxes are of the "Break Glass" type, a small glass slip maintaining the door closed.
To send a call tile glass is broken, thus releasing the lock, and the door of the box flies open under the influence of a spring, disclosing a loud-speaking telephone receiver and associated microphone, with clear instructions to the user.
The automatic opening of the box door closes the line circuit and operates an indicator on tile Fire Station switchboard. This in turn actuates a loud-ringing alarm bell, which attracts the attention of the duty man, who immediately connects his telephone with the calling line and speaks, his voice being amplified in the box loud speaker, and clearly audible at some distance from the box.
The box is reset by replacing the broken glass slip.
To facilitate maintenance and ensure the perfect working condition of the system at all times, a convenient means of testing is provided at the central switchboard in the shape of a sensitive voltmeter and associated keys, by the systematic manipulation of which earthed or disconnected lines may be readily detected.
THE A. T. M. FIREMEN’S CALL-BELL SYSTEM
The system consists of an electro-mechanism housed in a suitable case, on which are mounted the call keys.
There is a call key allotted to each man, together with a fire call key and a test call key. These keys are clearly labelled with their respective functions.
The mechanism is capable of closing contacts to ring the firemen’s bells for a period of 15 to 30 seconds continuously, or it may be arranged that an intermittent ring is obtained over the above period.
The keys associated with the men on the first call will be normally in the duty position, so that on the operation of the fire call key, bells will be rung in the homes of these men. If it is desired to call out an individual, the associated key is moved to the call position and the particular fireman’s bell rings as long as the key is depressed.
When it is desired to make a test call, the test call key is operated. This sends out the fire call, preceded by a suitable code to make the necessary distinction.
The Call-bell System can be arranged to operate from the main system on receipt of a fire call, thus reducing the alarm period to a minimum.
Last revised: October 04, 2012