Fighting High Fires from Below
The Method of Approach at Fires in the Upper Stories of Skyscrapers—Some Suggestions
IN this age of fire resistant construction, particularly in connection with tall commercial buildings, the question is often asked “why do skyscrapers burn ?”
The answer is simple: combustible contents.
A survey of any office building of modern design will show a great preponderance of combustible contents ranging from carpets and furniture to vast files of paper documents. This is illustrated very well in one of the pictures in connection with this article which shows the condition of a file room of the new Equitable Building, New York, after fire had been extinguished therein.
As long as combustible furniture, office fittings, and stationery are employed in modern buildings, there will be possibility of such buildings being visited by fire on a large scale.
The average skyscraper represents a very severe fire to handle. This applies to the larger cities as well as the smaller. In smaller cities skyscrapers arc usually isolated, which means that there is no method of approach to a fire on one of the upper floors other than by wav of elevators or stairwells. In large cities skyscrapers are sometimes adjacent, hut the new building laws commonly found in large cities which require that set-hacks he provided on tall buildings, result in the towers of such buildings being quite a distance apart. Thus in the future it may be expected the skyscraper problem in the large city will be almost as severe a fire problem as in the medium sized or smaller city.
The problems incidental to handling fires in tall buildings are many. The great height is the underlying cause of practically all such problems. Lofty buildings mean slow work, and plenty of it, in getting streams in operation. While standpipe systems may provide sufficient water for a fire involving one floor, where fire spreads over several floors the standpipe equipment of a skyscraper will not be sufficient to provide the department with enough streams for quickly bringing the fire under control. Hence it is necessary to stretch lines from the street to the floors beneath the fire which means heavy work for a large number of men, to say nothing of the great quantities of hose needed for such operations.
The limited means of approach is an equally serious problem. Very few skyscrapers, particularly the upper floors, can be reached by streams operated from a neighboring building. The greater the height, the greater will he the breeze blowing, and the more difficult will it he to produce streams which will he effective at any great range. An example of this may he noted in the illustration of the Sherry-Netherlands Hotel fire else where in this article. In this case a stream operated from a neighboring building may be seen rising up over one of the lower sections of the fire building, but pro ducing almost negligible results insofar as extinguishing the main body of the fire is concerned.
Tt may he said that the channels of approach to the average skyscraper fire are from below, and are limited to elevator and stair shafts. Where elevators get out of commission due to the spread of the fire, congested stairwells may result.
One of the fundamental rules in fighting a fire is first surround it, but it is evident that this rule is not applicable entirely to skyscraper fires, particularly where the fire is burning on a floor well up in the building and still some distance from the top. It is impossible to cover the fire at the top.
The limited water supply available through standpipe systems is another factor which seriously interferes with efficient operation of the department. Each standpipe has a definite capacity, and thus a definite limit of usefulness. Furthermore, each standpipe has but one outlet on a floor, and thus again its service is reduced. Of course, two streams can he taken from standpipe outlet by use of a Y connection, but even if each outlet were fitted with such connection, we would still have insufficient connections, even were it possible to furnish an unlimited supply of water through the standpipe, to properly handle a spreading fire.
The danger of failure of elevators is always present. History of fire fighting shows quite a number of such incidents where firemen have been trapped due to cars stalling in elevator shafts subsequent to fire reaching the control or power mechanisms.
Congestion in stairwells incidental to fighting a spreading fire is a serious matter. It is one which can he reduced, though not eliminated.
Where the fire is at a considerable elevation, the department will be faced with the necessity of heavy engine pressures due to the so-called “back pressure’’ produced by the high water columns. Common practice is to allow 5 pounds hack pressure for each story of a building. Thus if a fire is being fought on the fortieth story of a structure, the hack pressure alone may be taken at around 200 pounds. To this pressure must be added the pressure necessary to overcome friction in hose and in addition, sufficient to produce a good stream at the nozzle. The sum of these three factors may create a pressure at the engine which only the best apparatus is capable of producing. Where large quantities of water are required, several engines may be necessary to deliver such a supply at the desired pressure. Thus again a difficult condition develops which is not encountered at fires in ordinary commercial buildings of moderate height.
The problem of radiation of heat from a fire building is severe where other buildings are in close proximity to the fire building. With very high fires this problem is, however, comparatively mild. On the other hand where a fire may be burning half way up a skyscraper the exposure hazard due to radiated heat may be severe, and may necessitate special action on the part of the department.
Skyscrapers under construction entail several other problems not encountered in finished buildings such as embers, defective water supply, elevators out of service, unprotected openings which constitute both fire and life hazard, and other points which make the operations of the department more difficult.
It is not often that skyscrapers are equipped with sprinkler systems, but where such is the case, a spreading fire may be avoided.
Operating on the Fire
As noted above, the department is usually confined in its field of operations to the floors below the fire floor. Where such is the case, lines have to be stretched from the floors below to the fire floor, and gradually spread out on this floor until this particular part of the fire is brought under control.
In getting streams to work, the standpipe, if in good condition, provides great help to the department. Single lines may be stretched directly from the standpipe on floors below the fire to the fire floor, but if the fire has gained considerable headway it will be best to use Y connections at each standpipe outlet so that the maximum number of streams may be employed from the outlets on the floors immediately below the fire floor.
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Engines will have to be put in operation at the street to supply the standpipe system, provided a high pressure system is not available. Even if the high pressure system is available, sometimes buildings are so high that the hack pressure and friction loss make it necessary to boost the pressure from the high pressure system or else put pumpers into operation to deliver water from the low pressure system at sufficient pressure into the standpipe. If pumping apparatus is not capable of delivering the pressures desired at the street connection of the standpipe system, it may be necessary to place them in tandem, that is, the intake of one engine connected directly to the discharge of another, and the intake of the other engine connected directly to hydrant. In this way the sum of pressure capable of being delivered by the two engines are added together at the outlet of the second engine, which will be approximately the pressure delivered to the street Siamese of the standpipe system.
Well Built Hose Needed
Of course, care will have to he taken to use only the best of hose for this operation, for where exceedingly high pressures are delivered directly into a hose line, there is possibility of the hose rupturing and delaying the operations of the department just at the time when a delay will represent the greatest handicap to the department. This likewise applies where engines are pumping through hose lines stretched up the face of a building, or up stairways to higher floors.
Where it is necessary to stretch lines up to the fire from the street, two methods of accomplishing this are commonly employed. The first is by stretching the line up the face of the building and supporting the line at each 50 foot length, or stretching it up the stairwell to the floor beneath the fire floor. The details of these operations have been previously described in this journal. In any case, sufficient pressure will have to be maintained at the engine to give satisfactory nozzle pressure at the end of the line.
In getting lines of hose in operation, elevators are sometimes employed, particularly in carrying men and sections of hose to the upper floors. Elevators are also sometimes used for snaking a line of hose up the shaft, although this operation is not commonly employed due to the fact that it may put the elevator shaft out of commission when the lines are charged, locking the car above, such lines.
In any case where elevators are brought into use for fire fighting operations, great care should be taken that only those cars whose hoist mechanisms are not seriously exposed to the fire are put into service. At a fire in New York City, men employing an elevator car were carried up beyond the fire floor due to the failure of control mechanism to operate, as fire had reached the hoisting machinery. Had the men not been provided with suitable equipment, they would have been trapped above the fire and possibly have lost their lives. For that reason it is very essential that men using cars carry with them axes and rool rojx*s so that in the event the car becomes stuck or stalled in the shaft, or passing the tire floor due to failure of control equipment, they will not lie cut off from rescue. It is extremely dangerous practice to order men above a tire in a tall building, even though the tire does not fully involve a floor.
Procedure in Fighting the Fire
The exact procedure to be followed in fighting the tire depends largely upon the size of building, location and number of standpipes and the height of the fire. In all cases, the usual practice is to connect engines to standpipe connections at street, send lines up the building to the floor beneath the fire floor and stretch up by way of stairway to fire floor.
Insofar as covering exposed buildings, which are in danger of becoming ignited through radiated heat is concerned, this is usually accomplished by putting the standpipe equipment in the exposed building to work, and directing streams from the windows above the exposed section so that the shower so produced will cool off the atmosphere and prevent ignition. In some cases lines are stretched to windows directly exposed to fire and operated therefrom. In any case, the spray produced by streams from a great elevation are most effective in killing the heat incidental to a neighboring fire, and are apt to accomplish considerable in the way of checking the spread of the fire.
In some cases, where the buildings are sufficiently close together standpipe equipment in adjoining buildings may be brought into play for operating on the fire and preventing its spreading externally to floors above. To accomplish this it may be necessary to stretch lines from the standpipe outlets on different floors, siamesing them into a single line equipped with large nozzle. The large nozzle will give good range, give a stiff stream, and produce effective results in covering exposures.
As a final word it may be mentioned that high fires require great numbers of men and for this reason, even though the extent of the fire would not ordinarily necessitate a multiple alarm if the fire were one or two stories above the street, in the case of a skyscraper fire no time should be lost in sending in additional alarms to make sure that plenty of men will be on hand to carry on the heavy work which will be required of them.