VENTILATION AT FIRES

VENTILATION AT FIRES

WILLIAM E. CLARK

Supervisor

Wisconsin Fire Service Training

ABOUT THE AUTHOR

When should it be used . . . How to achieve it . . . What it can do

IF A SUITE of living room furniture, consisting of a davenport and two overstuffed chairs, were in an open field and ignited, the resulting fire would not be difficult to extinguish with a small amount of water. In fact, firemen could walk up close and extinguish the fire with a pump tank.

*Adapted from “Fire Service Training” Volume 1—No. 3, published by the Wisconsin State Board of Vocational and Adult Education, C. L. Greiber, director.

If the same furniture were burning in its ordinary location, a living room, the job of extinguishing the fire might not be so easy. In many cases, firemen might be incapacitated by the smoke and large amounts of water would be necessary. In other instances, the failure of the firemen to get in close and quickly extinguish the fire could result in extreme damage to the building.

What causes the difference?—The amount of ventilation! The furniture burning outside is no problem because heat and smoke rapidly dissipate into the atmosphere. The same furniture burning in a building will cause large amounts of heat and smoke to build up within a structure because heat and smoke can’t escape to the outside atmosphere fast enough. Consequently, firemen have to advance to the fire under very unpleasant conditions. Even if they are protected by masks, the heat may be punishing and lack of visibility a problem.

Difficulties posed by an interior fire can be greatly reduced by making the conditions as similar as possible to those of the outdoor fire; that is, to thoroughly ventilate the building. However, ventilation should not be performed in a haphazard manner. It is a subject in fire fighting second in importance only to the application of water—and in many cases is essential to permit proper application of water. Every fireman should be thoroughly acquainted with it.

What is ventilation?

Ventilation, applied to fire fighting, means the planned and systematic removal of smoke, gases and heat from a structure and is performed for any of several reasons:

  1. To save life by removing smoke and gases endangering occupants of the building who are trapped or unconscious.
  2. To discover exact location of fire by allowing smoke to lift.
  3. To permit firemen to enter and remain in the building to extinguish the fire and search for helpless occupants, as well as prevent extension of the fire. At most fires, the purpose of ventilation is to permit the firemen to advance close to the blaze and extinguish it quickly with a minimum of damage. The danger of asphyxiation is reduced, discomfort lessened and visibility improved to make operations safer and more efficient.
  4. To prevent backdraft or smoke explosions. The so-called “backdraft” or “smoke explosion” is actually an explosion of carbon monoxide mixed with air. Carbon monoxide is given off at fires where there is insufficient ventilation for complete combustion. If a door is opened, sufficient air may enter and mix with the carbon monoxide, forming an explosive mixture. If there is sufficient heat present to ignite this mixture, an explosion may result. This is a rare occurrence, but a dangerous one responsible for many deaths and injuries. Therefore, the possibilities must be considered. Proper ventilation may prevent it or lessen its harmful effects.
  5. To control spread of fire. Heat rises until it meets an obstruction such as a roof or ceiling. It then travels horizontally, seeking an opening where it may rise again. An opening made in a roof will “pull the fire” to that opening and allow it to vent upward into the atmosphere through that opening. Air currents are set up which cause the fire to move in that direction and tend to keep it from spreading elsewhere. Such an opening made directly over the fire will help to localize it, but an opening made at another spot will draw the fire to that location.

When should ventilation start?

Ventilation should be performed at fires in buildings, ships or other enclosures where smoke is present; also where gases or fumes have accumulated from causes other than fire.

Ventilation should begin as soon as water is up to the nozzle, not before. Opening up a building permits more air to get to a fire and accelerates burning. A charged hose line must therefore be ready for action as soon as ventilation begins. There is an exception to this rule: A skylight, scuttle cover or door at the top of a stairway in a multistoried building may be opened to prevent “mushrooming” or heat and smoke banking up on the top floor, when this would endanger human life. This can be done without waiting for water.

Ventilation locations

  1. At the roof: Heat and smoke rise, accumulate at the topmost point, then start banking down. An opening in the roof will permit smoke and heat to escape rapidly. When there are no natural openings in the roof such as skylights, scuttle holes, etc., and conditions are not severe enough to warrant cutting a hole, ventilation of the attic or top floor must suffice. Roof ventilation is often valuable even though the fire is in the lower part of the building, or in the basement. A hole may be cut in the roof when fire is in the cockloft or top floor and sometimes when fire is elsewhere in the building and a heavy smoke condition prevails on the top floor that cannot be removed sufficiently by other means.
  2. At windows: Windows should be opened on the floor where the fire is located and on all floors above that where the smoke has accumulated. Usually there is no advantage to opening windows on floors below the fire.
  3. At doorways: Doors should be opened to permit air circulation to remove smoke.
  4. Any other covered or partly covered opening on a level with or higher than the fire should be opened.
Smoke ejector in use as blower over sidewalk grating during smoky basement fire. Note use of ladder as protective measure to prevent firemen from falling into opening

Philadelphia F. D. photo by Kennedy

Paterson, N. J., fire fighters open up attic during residential apartment blaze last December. Fatal fire took lives of three small childrenWhen a window shade will not roll up easily, it may be removed by a short turn of the roller. Closed shades, blinds and curtains may obstruct ventilation through open windows and should be opened or removed

West Milwaukee F. D. photo

How is ventilation performed?

When an entire building is to be ventilated, such work should begin at the top of the structure and proceed downward, floor by floor. If the lower part of the building is opened first, fire may break through the window openings there and make ventilation of upper floors impossible or endanger men who may be ventilating or performing other duties above the fire.

Opening roof: Firemen go to the roof and remove scuttle covers, skylights, etc. and sometimes cut holes in the roof surface. One large hole is better than several small ones. It should be cut directly over the fire, if possible, but not at a point that would endanger an adjacent building.

Skylights may be removed by prying loose the coaming and lifting the skylight or by loosening the coaming on three sides, leaving the fourth for a hinge and folding the skylight back onto the roof. When removal is not feasible, individual glass panes may be removed without damage by prying up the metal divider strips and sliding the glass out. If no other means will work, the glass may be knocked out with an axe or any other tool.

Opening windows: If conditions permit, this should be done by firemen working from the inside. Blinds and shades should be raised or removed and drapes and curtains pushed back or removed to permit smoke to escape. Screens should be removed and storm windows removed or broken out. Some fire officers believe that double-hung windows should be opened two-thirds of the way from the top and one-third from the bottom, but this is of little consequence. The main point is to get the window open at the top to let the smoke escape. Fresh air will find its way in to replace it. Good cross-ventilation can be accomplished by opening windows on the leeward (away from wind) side of the building at the top, and those on the windward side from the bottom.

Casement and factory-type pivoting windows have to be opened according to their design. Many windows are difficult or impossible to open in the allotted time. If smoke conditions warrant it, they should be broken. Glass is the cheapest part of most buildings and much valuable property has been destroyed by flames because firemen hesitated to break windows that couldn’t be opened.

A quick way to break glass above the ground floor is to raise a ladder and let the top of it fall against the window. It can be moved from window to window, doing the job much quicker and more safely than could be done by a man working from a ladder.

Plate glass show windows in most stores usually have a lighter glass transom located above the heavier glass. This is easily broken and often affords adequate ventilation, permitting the show window to remain intact. In extreme cases the plate glass may be removed. In either situation, if there is a partition between the store and show window, it must be removed.

Basement fires: Basement or cellar fires present special ventilating problems. Windows, where present, and doors should be opened. Sometimes windows are recessed in enclosures covered with an iron grating at street level. This grating may be removed by breaking the concrete at the corners, or the bars may be spread and a pike pole is inserted to break glass.

When deadlights are present in the sidewalk over a basement, they may be knocked out with the back of an axe, a hammer head pick, or a maul. The removal of coal chute covers may also assist ventilation. In some stores, the removal of panels under the front of the show window gives direct access to the basement, affording good ventilation.

Where no other means is effective a hole may be cut in the floor above the basement. This should be guarded by a charged hose line. Hot air heating registers in floors can be utilized by removing the grille and pushing down the hot air duct. This will have the same effect as cutting a hole in the floor and is quicker and less damaging.

Ship fires: Some fire departments may be called upon to fight fires aboard sea-going cargo ships. Ventilation aboard ships calls for “trimming” ventilators, that is, turning the ventilating funnels away from the wind, removing hatch covers (it should be remembered that there may be additional hatch covers at the “tweendeck” level), and opening lazaret hatch doors. Engine rooms are often equipped with skylights similar to those on the roofs of buildings which may be treated in the same manner to effect ventilation.

Windows may be opened or broken from above by use of a pike pole. Note fireman stands to one side for protection against heat that may issue after opening is made. This is an important safety tip

—West Milwaukee F. D. photo

Mechanical ventilation: In addition to ventilation by natural means, movement of smoke, gases and air can be forced by mechanical devices. Fans of varying size are employed by many fire departments; these usually range from 5,000 to 15,000 cfm capacity.

Since the use of fans has become popular, there is a noticeable tendency in small fire departments to neglect natural ventilation. In fact, many poorly trained fire departments depend almost entirely on mechanical ventilation and overlook the advantage of opening windows, etc., as previously described. Smoke ejectors are valuable when properly used, but they are best used as an adjunct to natural ventilation, or in cases where natural ventilation is ineffective.

If the results of natural ventilation are not satisfactory, a smoke ejector should be used. It must be remembered that if not properly employed, they can do more harm than good. An exhaust fan will draw the smoke and fire toward the fan; therefore, the location must be carefully selected.

This problem was exemplified at a recent fire in the attic of a one-story dwelling. The firemen were able to enter the ground floor with ease, only a slight amount of smoke was present there. They placed a blower fan in the front doorway and an exhaust fan in the rear dorway. In a moment a large volume of smoke was drawn from the attic into the first floor and the firemen were driven out of the building.

Fog nozzles have been used for ventilation for more than 80 years, yet today we find many fire departments using them only for extinguishing the fire. Common fog nozzles induce a great amount of air to follow the fog stream and can move from 10,000 to 30,000 cubic feet per minute depending upon size, type, fog pattern and location of nozzle.

To remove smoke with a fog nozzle, the nozzle is held inside a window or doorway and aimed toward the outer air. Experiments in Wisconsin show that the wider the fog pattern, the greater the air movement, but the pattern should not cover the entire opening. Better results were obtained when the nozzle was a few feet from the opening than when it was close to it. The same precautions mentioned for the use of fans apply also to the use of fog nozzles for ventilation.

Ventilation precautions

It should be remembered that a hose stream aimed into a window, doorway, skylight, hole or other opening has tile same effect of nullifying ventilation as if the opening had a cover placed over it. At the same time openings should not be made where they may jeopardize nearby structures by extending the fire unless adequate protection in the form of hose streams is at hand.

When holes for ventilation are cut in a floor, they should be near a window if possible. The relieved smoke will then go through the open window. If men with a protecting hose line are driven out of the building, upward extension of fire through the hole can be prevented by directing a stream from the outside through the window. It is not desirable to cut holes in the path of travel because firemen may step into them.

Whenever a hole is cut in a roof or floor, or a skylight or scuttle cover is removed, the opening should be probed with a tool or pike pole to find if there is any obstruction, such as a ceiling, below the hole. When such obstruction is found, it should be opened or pushed down.

When breaking glass, make sure no one below will be struck by the falling debris. Warning should be given in ample time.

Photos illustrate how one man may work from a ladder placed between two windows to open or break both without moving from his position. If the ladder were directly under the window, he would be endangered by falling glass. If he were higher on the ladder, he might be endangered by a heat blast following ventilation

-Photos courtesy West Milwaukee F. D.

Ventilation at Fires

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Ventilation at Fires

Importance of Removing Hot Cases from Buildings on Fires, and How This Should be Done

MANY Civil Service Examiners dwell extensively on this important subject of ventilation where examinations are held for promotion in the fire service. At a recent examination held for the position of Captain, the following questions were asked:

Question: What benefits are derived from ventilation?

Answer: Proper and timely ventilation will relieve the building or floor of pent up gases, smoke, and heat. 11 will allow the firemen to get to the base of the fire quickly. It will afford those who may be trapped in the building a Ix-tter chance of escape. It will prevent the mushrooming and lateral spread of fire. It will prevent a backdraught. It will greatly lessen the punishment firemen are subjected to in the inhalation of smoke, heat, and toxic gases.

Start of Ventilafion

Question: Where should ventilation begin, and why?

Answer: Ventilation should always begin at the roof or above the fire. Tt is considered good practice to start at the roof to ventilate when the building is not over six stories in height. Any building over six stories in height can he properly ventilated by beginning at second floor above the fire floor. I do not wish to imply that this is an applied rule, much must be left to the judgment of the officer in charge of the fire. Each building should be considered from the view point of conditions encountered, such as; location of fire, the extent and duration of fire, construction and type of building, wind conditions, and overhead exposures sides and rear.

Question : What precautions should he taken by firemen while ventilating?

Answer: Firemen should always protect themselves while working on the roof of a building. If you go to the roof by way of inside stairway and scuttle hole at night, he sure you do not step off edge of roof as scuttle may he built near edge. If the roof is covered with snow, be careful you do not step on skylights that are built a few inches above roof level. (A fireman lost his life on the roof of a one-story taxpayer in this manner). In cutting holes in roof, always cut them with the wind at your back.

Front a pnv»er presented at the Poughkeepsie convention of the New York State Fire Chiefs’ Association.

F. A. Murray

If firemen are sent to roof to ventilate through inside stairway, the chief in street should as soon as possible place ladder to roof, so that men would have two avenues of escape. Do not stand close to outside cellar windows when ventilating a cellar fire, as fire is liable to leap a distance of eight or ten feet from window. Use pike pole or short ladder to break cellar windows, standing well back from window. When breaking plate glass windows to ventilate a store fire, stand well back to one side, never in front of window. Use pike pole and strike the window at the too. Continue to strike down, and be sure and clean all the glass from the frame, this is most important, it will prevent large sections of glass from sliding down pike pole and inflicting serious injuries.

No less than two firemen should be sent to roof to ventilate, and proper tools should always be taken along such as, ax, pike pole, tin roof cutter, and life rope. Of late years we have an added hazard on the roofs of nearly all buildings, I refer to the maze of radio antennas. These wires create a very dangerous situation especially when working at night and with a heavy smoke condition.

Common Question On Tests

From this sample of questions, you will readily agree that “Ventilation” is uppermost in the minds of Civil Service examiners.

One of the most important factors to he taken into consideration when proper ventilation is to be provided, is to have large water lines laid and charged before the building is opened up. Many fires have extended due to the overlooking of this important matter. The indiscriminate opening up of windows, doors, roof covering, etc., of a building on fire might very readily lead to serious loss of life and extensive property damage, if large water lines are not in position to extinguish or head off fire.

In ventilating a roof, all portable openings should he given first consideration. If these openings seem inadequate, and excessive heat or fire is confined in cock loft, then holes will have to be cut in roof. Do not cut roof supports, confine activities to cutting between roof beams, and make hole of sufficient size as to allow for complete ventilation. Good judgment must be exercised in that no hazard is created to any adjoining property. When cutting holes on roof, see that there are no obstructions under roof, such as hanging ceiling, or double roof. If ttiese are encountered, you will have to punch a hole through with plaster hook, or other tool. Thorough ventilation cannot be obtained if this is not done.

Attic Is Important

In fighting a fire in a dwelling, although the fire may be in the cellar, never overlook the immediate detailing of at least two firemen to the attic. This should be done immediately upon arrival. We are all familiar with the contents of the vast majority of attics, stacks of old newspapers, magazines, old furniture with the excelsior, burlap, and hair filling exposed, old mattresses, etc. All of these make ready fuel for fire, and may ignite from heat. Do not be in too great a hurry to cut holes in dwelling house roof. If there is a scuttle, remove it, open windows, have booster line ready to operate in case small fire is encountered. Only open the roof when you find it impossible to get into attic. In opening the roof, try and get directly over tire, open at the highest point near ridge pole but do not disrupt ridge pole.

A tire in basement of a one-story taxpayer with only entrance to cellar through trap door at rear of the individual stores, presents a serious situation. Owing to the accessibility to enter cellar, fire very often spreads over the entire cellar area. In order to facilitate the entering of cellar through these inside trap doors, it is necessary to ventilate stores above. The most practical method of doing this is to cut holes in floor just inside of plate glass windows, first having removed the plate glass from the frame. Always remember that when holes are cut in store floor, to place some object in hole to protect men working on floor from falling in same. Most basements are no more than huge holes in the ground affording very little opportunity for oxygen to enter. Therefore fires in basements are prolific producers of carbon monoxide gas, which is accountable for the fact that the greater number of firemen are overcome when fighting basement fires. The use of self contained oxygen masks should be more generally used at basement fires. I know of one large eastern city that now has about one hundred such masks.

Role of Wind

Wind direction plays an important part when ventilating. Opening window’s on the windward side of a building may not produce results, unless windows are opened on the leeward side. Best results are usually obtained when cross ventilation is employed. Use extreme care and judgement in opening wire glass window’s and iron shutters, where in so doing adjoining building may be exposed to fire.

Atmospheric conditions greatly’ affects ventilation. Did you ever stand in the street where smoke conditions were nearly as bad as inside the building? I am sure you have, observed the inability of y’our chimney to carry aw’ay smoke during the starting of a fire in your furnace when the air was not right. Both of these conditions are the result of atmospheric density’. When this condition exists, the gases and smoke hang along the ground. Opening of the roof and upper stories will not suffice, it is absolutely necessary under such conditions to open all windows on lower floors.

The element of time plays an important part in the proper ventilation of buildings on fire. If it w’ere possible to properly time our ventilating operations with the proper placing and operation of hose lines, then we would he really accomplishing something worthy.

All Volunteers Should Be Trained

In training firemen, I have found that in many volunteer departments, the personnel of engine companies would have nothing to do with ventilation, or in fact any operation classified as the duties of a ladder company. I believe that every member of a department should be well trained in all of the duties that a fireman may be called on to do.

Never overlook an adjoining building that may he charged with smoke and heat which has entered window’s or party wall opening. This building should be given immediate attention and ventilated.

Ventilation should always be accomplished first, if possible, by the opening of windows, or the removal of portable coverings. Windows should be lowered from the top, and raised from the bottom. This will allow the smoke, heat, and gases to escape from the top, and fresh air to enter from the bottom. Sometimes it is better to alternate every other window, one down from top, the other up from bottom. With this proceedure. firemen have a better means of entry or exit by way of ladders to and from the floor.

Care in Rural Areas

Volunteer fire departments operating in rural districts, with a limited amount of water, should exercise extreme caution in ordering the building ventilated. Only such parts of the building should be opened up that will allow firemen to direct streams on base of fire, or to head same off. Firemen are called on to take excessive punishment at these fires, as their limited water supply must he conserved, and not a gallon wasted. Where it is necessary to replenish booster tanks, then ventilation should be of an intermittent nature. I term this procedure “partial and intermittent ventilation.”

I have seen buildings destroyed, also the unnecessary extension of fire due to improper ventilation. It is my belief that the officer in charge of a fire may be partially responsible for improper ventilation.

Let us assume that a Chief has arrived some time in advance of a ladder company, he has completed his survey and has ordered w’ater lines laid. The ladder company arrives and the officer is ordered to ventilate, he not being familiar with the chief’s previous orders, nor has he the time to make his own personal size up. He proceeds to do just what the Chief ordered. The building is opened up, and if there is any delay in laying additional lines to properly cover the building, it is possible the fire will extend due to its being improperly ventilated.

Orders Should Be Specific

I believe the officer in charge of the fire should give more specific orders; such as; Ventilate roof, or roof and top floor, or top floor only, or specific locations mentioned in his order. He may then order additional ventilation later, as would he justified by having charged water lines available. This method is as near as we can hope to reach in proper timing of ventilation.

Excerpf from Book

That very splendid book “What Ever’l ire Fighter Should Know.” published by FIRE ENGINEERING, has this to say regarding ventilation:

“Probably no subject has received more deserved attention in recent years by those who give careful thought to fire fighting than the subject of ventilation.”

1 say that ventilation is probably the most important of all acts relative to the successful extinguishment of fire. 1 say this for 1 believe that we can commit a serious error by the act of ventilating. (ventilating improperly) also by failing to ventilate at all

While reams could be written on this important matter, 1 only attempted to cover the most important features of this subject.

Ventilation is a means to an end. That end to all fire department members, whether you are part of the large city department, or the small volunteer department is: The extinguishment of fire in the shortest space of time with the least fire and water damage.

To me there is nothing mysterious connected with the extinguishment of fire. I say this for the reason that 1 have heard Chiefs in the smaller cities and towns admit that they were afraid to tackle a large fire as they were led to believe it required long years of experience to handle such a type fire. 1 cannot concur with such a belief, for it is my honest and candid opinion that a modest amount of experience, to which has been added the catalogued experiences of others, together with close application of study and good common sense, will result in an intelligent fire officer.