Impact of Wartime Fire Defense Upon Peacetime Fire Fighting
Further Details of How Municipal Fire Services May Benefit From the Navy’s Wartime Fire Suppression Experience
THE United States Navy is most anxious to cooperate with Municipal Authorities, industrial firms and others having fire protection problems to give them the benefit of the Navy’s war time experience with fire. The research and test projects leading to the development of the United States Navy Fire Fighting Equipment and Techniques were conducted on a large scale.
Individually no municipality could finance research on such a gigantic scale. It was made possible through American tax dollars. While secrecy was necessary during the war the Navy now desires to make that information available to all who have a legitimate interest.
No doubt firemen are most anxious to learn what the Navy has developed during the war that may be used with effectiveness in their local municipalities. No. 1 on that list will be the Navy’s experience with fog spray. Fog nozzles were in use before this war. The Navy does not lay any claim to having invented them; however, the Navy did develop the so called “all-purpose fog nozzle.” This is a three-position nozzle which will permit the operator to discharge water in the form of finely diffused spray or fog in one position, in the form of a solid stream in a second position, or shut the stream off entirely in a third position, all by manipulating a single control handle. Once the discharge from the Navy all-purpose nozzle is set in the fog position, it can not be adjusted; however, discharge is set for maximum effectiveness. There are types of fog nozzles which are adjustable and in the hands of professional firemen these should produce results comparable to the Navy product. However, our problem was to put a piece of equipment in the hands of relatively untrained and unskilled men who could not change the characteristics of the fog by tampering with the nozzles, as might be the case in the excitement of a fire.
The characteristics of the water fog discharge of fog nozzles are all important. If the water is not finely diffused, homogeneous and without voids, it becomes a spray and is relatively ineffective. If it becomes too finely diffused under extremely high pressures it does not carry enough quenching or cooling effect.
Let us consider the basic principle underlying fog for a moment. One pound of water will absorb 977 BTU’s. By breaking up a solid stream into diffused fog or spray, we present a tremendously increased surface area; consequently we most nearly approach the maximum or optimum rate of absorption. This, then, is why the water fog is able to absorb such tremendous amounts of heat. It accounts for the ability of fire fighters operating behind such equipment to approach very close to the seat of a fire regardless of its intensity.
Like every other piece of equipment, in order to obtain the best service, it is necessary to realize its full possibilities and limitations. Fog distinctly is not a cure-all for all fires nor will water-fog alone extinguish a large scale gasoline fire. It will, however, control the combustion so that a close approach is possible, but in order to effect extinguishment completely, it is necessary to use foam or fog-foam. In municipal use it permits a fire company to reach the very seat of a fire and to attack it without severe physical punishment.
However, it should be borne in mind that ventilation is necessary. When using water fog the attack should be made from one direction only and ventilation should be provided at the point toward which the attack is progressing. This is particularly necessary when attacking fire through a long passageway or corridor or it may be found that the gases of combustion have been compressed to a point where they will overcome the ability of the fog to restrain them and will flash around the fire party. If ventilation is provided, howeves, it is remarkable to see the ease and speed with which a floor may be cleared of smoke and the very heart of the fire reached. This perhaps is one of the outstanding possibilities of water fog.
Effectiveness in Fixed Installations
The performance of water-fog in fixed installations is also remarkable. Tests were made at Findlay, Ohio, with such an installation in a 93-foot diameter tank. This tank contained a quantity of crude oil, which was ignited. The water fog was controlled by a heatactuated device which kept the tempera ture below 300° F all through the fire. Where structural steel is exposed and protected by water fog, we found that in no case was there serious warping or deflection of the structural steel members.
Fog should prove valuable for exposure protection in building fires. Some fires are deep-seated and will require a solid stream for penetration. The Navy all-purpose nozzle provides for this in that the control handle permits an instantaneous switch from fog to a solid stream or from fog or solid stream to a shut off. The case for the Navy allpurpose nozzle can be briefly summarized as follows:
In the October issue of FIRE: ENGINEERING there appeared an article by Jerry Daly entitled “Navy Fire Fighting Techniques to Benefit City Fire Fighters.” This briefly outlined some of the advancements in the science of fire suppression developed by the U. S. Navy. It also told something about the man most resonsible for these developments, Commander Harold J. Burke, U.S.N.R., Chief of the Fire Damage Control Service, Bureau of Ships, and former Deputy Chief of the New York Fire Department.
In this article, Commander Burke discusses the relationship between the Navy’s wartime fire fighting progress and the municipal fire service’s postwar problems at greater length than was covered in Jerry Daly’s October article.
In view of the considerable and widespread publicity being given the application of wartime fire protection procedures and products to peacetime fire suppression in this country, and in view of the importance attached to the statements of Commander Burke, this article, which represents the major portion of an address delivered before the Fire Chiefs’ Emergency Plan of Westchester County is published. The editors desire to thank Secretary of the Navy Forrestal, and the Westchester “Plan” as well as Commander Burke, for permission to publish this message, which we believe will be of interest to all forward-thinking members of the fire service.
Official Photograph U. S. Nary
It is in one a controlling nozzle which will produce a solid stream or waterfog instantaneously as desired. The operator is always assured of optimum water diffusion.
It is ideal for use on inflammable liquids. It can be used to generate fogfoam in case of gasoline fires. It should result in considerable saving in water damage. It will permit the fireman to reach the very seat of a fire with a minimum of physical exertion and punishment and at maximum speed.
Mechanical Foam Improved
One of the most interesting developments of the entire war has been the development and perfection of mechanical foam. The term “mechanical foam” is used because this material generates foam through a mechanical action rather than a chemical action. It is a liquid and is governed by the same laws of hydraulics as water. Its specific gravity is slightly high, being 1.125. In order to produce mechanical foam, four conditions must be satisfied: First, we must have water; second, the foam liquid; third, air; and fourth, they must be in the correct proportion.
The correct proportion for mechanical foam is 6% of foam liquid by volume to water. The air may be introduced through aspirating cages or even entrained into the streams by the action of the impinging jets after the water has actually left the nozzle. Mechanical foam can be introduced into a water stream at the suction side of a pump, at the discharge end of a hose line through a pick-up tube or at an intermediate point in the line through a proportionerpump, or by using a duplex pressure proportioner. The foam so produced is more fluid, flows more readily around machinery foundations, through lightening holes in vessels and is generally superior to chemical foam.
The foam liquid is made from a variety of proteins running all the way from soy beans to horn and hoof meal and even fish scales. More recently foam has been made from dried animal blood. As a matter of fact almost any protein (vegetable or animal) can be used to make foam if properly treated and processed.
United States Navy specification foam has a relatively low expansion rate, of from 6 to 8. We prefer this expansion because it provides a more permanent blanket. Higher expansion foam generally breaks down much more rapidly and exposes the surface of the oil to reflash. This is particularly true when surrounded by heated metal bulkheads
Pick-Up Foam Nozzle
The standard Navy foam nozzle is fitted with a pick-up tube through which foam-liquid can be drafted from the 5-gallon container in which it comes packaged. Speaking in the terms of municipal fire protection, this means that 3 or 4 cans of foam liquid on each ladder truck, plus one or two nozzles, will provide foam protection for the average oil or gasoline hazard, such as encountered in a garage, dry cleaning establishment, or filling station. In those areas where tank farms or oil refineries are located, some of the more elaborate equipment should be furnished, in fact the proportioner pump in the 500-gallon capacity size is light enough to be completely portable and is capable of furnishing 500 gallons of foam in liquid form each and every minute. Since the expansion rate is from 6 to 8, this means that between 3,000 and 4,000 gallons of foam a minute can be produced through this piece of apparatus. The unit weighs but 185 pounds and would provide excellent auxiliary equipment for use in connection with the ordinary fire department pumpers. It is also possible to use mechanical foam in a premixed state, as long as 6% of the foam liquid by volume is mixed with 94% of water. The combination will furnish a very satisfactory foam and can be discharged through a regular fog nozzle or through other equipment.
Navy Rescue Breathing Device
The next piece of equipment which I predict will find extensive post war municipal use is the so-called Navy Rescue Breathing Apparatus. This is an oxygen type of mask which employs a canister. However, it is not to be confused with the all service type mask which is a filter type mask.
The Navy mask is so constructed that the exhaled breath passed over a chemical in the canister will generate oxygen. This oxygen in turn is led to a breathing bag from where it is fed to the wearer in the form of breathable air. Since there is no bottle oxygen and there are, generally speaking, no valves to get out of adjustment, it is not affected by the jars and jolts of apparatus.
This mask will provide complete protection against any gases except those that have skin penetration characteristics, such as ammonia. Of course, in such cases wading pants and the usual skin protection equipment must be used.
Each canister used with the Navy mask is normally good for about one hour of ordinary operation; at an accelerated rate of exertion, the usable time of the container is cut down to about 40 minutes. Containers can be changed instantaneously by the release of a bale device, through which they are held in the canister container. The whole apparatus weighs but 1 1/2 pounds and is compact and should be of utmost value in overcoming smoky and stubborn first alarm fires that often prove so difficult.
It my opinion the combination of the rescue breathing apparatus and the fog spray nozzle provides an ideal team, the first against the smoke hazard and the second against the heat barrier. In combination there is no practical reason why well trained fire companies should not be able to go practically any place desired in a building on fire and with perfect safety. Until recently it was not possible to buy this apparatus commercially because of the security conditions with which the Navy surrounded it.
Official Photograph U. S. Navy
Official Photograph U. S. Navy
Portable Cutting Outfit
Another piece of equipment that has proven of a distinct advantage to the Navy in fire fighting is the pack type portable oxy acetylene cutting outfit. While this is not new in fire department service, the Navy has increased the capacity of the unit tremendously through design changes until now it has quite an increased capacity, improved cutting torch, better portability and weighs but 55 pounds.
Navy Fire Defense Training
Of major concern to the Navy and, I am sure, also a major concern of the Fire Chiefs in this country, is the problem of firemen’s training. Fire departments in this country have many fine training schools but in general the instruction is theoretical rather than practical. Shortly after Pearl Harbor, in an effort to make the training of fire fighters in the Navy realistic and actual, we built simulated ships ashore. The hulls of these ships were reinforced concrete and they were lined with brick; however, the interior arrangements, floor plates, ladders, gratings and obstructions closely resembled those which the sailors would find afloat. These structures were arranged so that they could be flooded with oil and ignited.
As a result real fires, more intense in most instances than what the sailor would encounter afloat, were built and it was in these structures that the Navy fighters were trained.
Prior to attacking fires on these socalled ships, the students received a primary course of instruction on 15-foot circular tanks outside. In this way they were able to obtain some idea of the possibilities, range and capacity of the various pieces of equipment that they would use on the ship fire. However, the chief feature of the so-called ships was the fact that the men were taught by doing it.
I see no reason why the same principle cannot be applied effectively in training the fire fighters of our municipal fire departments. It need not be on as large a scale, but at least some sort of a simple structure where actual fires may be built and where the firemen will obtain a baptism of fire and feel the physical hardships of this job, and where he will learn how to get around in smoke and heat, would be invaluable. In fact our larger cities should build training schools that are in reality indestructible buildings, arranged in apartments, cellars, factories and similar occupancies. These structures should be of reinforced concrete and arranged to sustain fires. They should be so constructed that the light, ventilating and elevator shafts are reproduced. Means of egress and all types of fire escapes should be provided. Automatic sprinkler systems and all other fire fighting equipment required by law for that municipality should be installed. After receiving basic or theoretical instructions, the students could then practice on this structure, which would furnish a practical test ground. All sorts of combustible trash could be used for fuel.
I believe in this manner we will be able to produce firemen who are far better trained and have actually experienced more fire than they would have had had they been in ten years’ continuous service.
If the structure, such as I describe, is too elaborate and too expensive for any single city to construct, it may be possible to arrange for the construction of such a building on a state wide basis. Under state control, quotas could be set up for individual cities.
The Navy war experiences resulted in an interesting development in the use of foam for fighting fires in oil storage tanks. Prior to this war. most of the foam fire-fighting equipment installed for tank protection was placed over the top. However, in a bombing raid the blast effect caused the demolition or partial destruction of this “over the top” protection. Experiments were then made with injecting foam through the product line into the bottom of the tank. This technique proved to be remarkably effective until now it has been developed to a point where fire may be fought with practically slide rule precision.
Once the physicals of the oil in the tank are known and the amount for surface area involved is determined, it is possible to predict within a matter of a few gallons how much foam liquid will be necessary, within a hundred gallons or so, how much water will be required and within a minute, the length of time it will take to extinguish the fire. Only a slight modification is necessary in the piping of a tank farm to make this system work to perfection. A valved fitting to which hose lines can be connected must be provided in the product line as well as a stop-valve. The connection would be provided for accommodating large diameter hose.
Sub-Surface Application of Foam
Foam should be introduced into this product line at sufficient pressure to overcome the head of the oil in the tank. The foam itself may be generated through the use of venturi generators or through compressed air generators.
The action of the foam in sub-surface application is slightly different than that observed in surface application. The foam acts as a vehicle which carries water up through the heated oil, reducing the temperature as it ascends until it cools the surface. The foam finally forms a seal at the surface.
Through the cooperation of the Standard Oil Company of Ohio, the U. S. Navy recently conducted a series of fire tests in a 93-foot diameter tank at Findlay, Ohio. Crude oil and gasoline were fired in separate tests. Previous tests had been conducted with fuel oil. These tests proved conclusively that the sub-surface method of application is entirely practical.
Official Photograph U. S. Navy
It remain to be proved that this is also a practical method of protecting tankers and to that end the Navy intends to obtain the use of an old tanker that is about to be scrapped and will outfit it for sub-surface application and conduct large scale actual service fires to prove the feasibility and practicability of the method.
Another feature of the sub-surface application using mechanical foam is the fact that perhaps no other method or material lends itself so readily to automatic operation. Heat-actuated devices can control an entire system if necessary.
Fog-Foam a War Development
Another interesting development of the war has been the perfection of high capacity fog-foam equipment and technique. Fog-foam means discharging foam liquid solution through large capacity hose and nozzles of the impingingjet type which have a capacity of 550 gallons per minute or more.
This method of combatting oil or gasoline fires has tremendous possibilities, especially in dealing with large fires in tank and oil refineries.
The “fog-foam,” as the name indicates, is foam in a finely diffused form which affords excellent heat protection for the fire party; it is a veritable shield. The special nozzles used are provided with stream-shapers which transform the diffused foam into a solid stream when greater projection is required.
Fighting Cargo Fires
One of the most difficult fires to combat afloat are those in cargo loaded holds of merchantmen. Even the best trained fire department backed with the finest equipment is at a decided disadvantage because the seat of these fires is generally inaccessible.
Let me emphasize that there is no one medium that is ideal for all fires. Each fire extinguishing agent has a distinct field and good fire protection requires the use of all of these agents, each in its proper place and under the proper conditions.
The cargo-loaded hold, because of its inaccessibility, presents a situation where carbon dioxide can be used to great advantage. The technique of this type of fire fighting, to borrow a phrase from Mayor LaGuardia’s vocabulary, requires “patience and fortitude.” First, it is necessary to determine the cube of the hold; allowance may be made for impermeable masses.
The amount of carbon dioxide required can be roughly estimated as one pound for each 20 cubic feet. Sufficient cylinders of carbon dioxide should be provided to meet this requirement plus about 10% for maintaining the inert atmosphere through the duration of the fire.
The fire department should be prepared for this type of fire fighting by equipping itself in advance with a manifold having Tee check valves that will accommodate a minimum of six 50 pound cylinders of gas and with a metallic frost insulated hose as a discharge line from the manifold. With all of the equipment and gas in readiness a hole just large enough to receive the discharge hose should be burned through the deck and the CO2 discharged. The total amount of gas required for the cube of the hold should be injected as rapidly as possible. Sources of possible leakage such as hatches and ventilators, should be covered or secured.
After the initial discharge of gas has been completed an analysis should be taken at half hour intervals to determine that the carbon dioxide concentration is adequate. An additional cylinder should be bled into the hold from time to time to maintain the required concentration.
Since carbon dioxide has little cooling effect, it will be necessary to maintain an inert atmosphere for many hours in the burning hold. It is recommended that in the case of serious fires at least 12 hours elapse between the initial discharge and the preliminary investigation of the hold. Such investigation must be made by men equipped with hose masks or oxygen breathing apparatus, since there will be an oxygen deficiency in the hold.
It is important to keep the fire area under a constant concentration of gas and it is likewise important to avoid impatience. Once the hold can be entered, overhauling should proceed by removing any unburnt material or merchandise and landing it or placing in on lighters which may be brought along side. Any material that shows evidence of fire should be left until last. Charged hose lines should be ready in a standby position to quench any small or smoldering fire that may be uncovered.
Generally speaking, the only damage that will result from fires fought this way will be purely fire damage and the water damage will be held to a minimum. In the near future, the United States Navy intends to conduct largo scale tests of fires in cargo loaded holds using carbon dioxide for the extinguishing agent.
During the war the Navy has had considerable success in training through the use of audio motion picture films. It seems to me that there is a tremendous field for the development of this training aid in fire department work. Under the supervision of auspices of the International Association of Fire Chiefs it may be possible to produce a series of motion pictures that will show the correct technique and method of fighting all of the various types of fires, the approved method of ventilating and of overhauling structures after fires.
Through the use of such films a standard of good practice may be established. Animation should be used extensively to show clearly and exactly the principles involved. The ultimate result will be the dissemination of authentic information which should in time produce better fire protection generally.
I have only touched the high lights and pointed out some developments that would have particular application in municipal fire protection. There have been other developments, particularly in the field of portable pumping equipment that are most interesting. For example we now have a pump that will deliver 500 gallons per minute at 125 pounds per square inch and yet it weighs but 230 pounds.
Tomorrow’s Fire Service
In summation. I recommend serious thought be given to the use of water fog, particularly when discharged from a 2-position nozzle. I predict a wide spread use of this technique. It is not experimental. It has successfully passed through tougher service tests than any city is apt to give it. Coupled with the rescue breathing apparatus, it provides fire departments with equipment that should make it possible to reach the heart of practically any fire with speed and dispatch, but without severe physical punishment so well known and so damaging to firemen. It is silly not to use the breathing apparatus when simple dependable equipment is available.
Mechanical foam affords the most potent extinguishing agent for handling gasoline oil fires.
We must be ready to take full advantage of two-way radio communication including improved “walkie-talkie” equipment.
Pneumatic equipment has tremendous possibilities in the fire service, par-
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U. S. Army Corps, of Engineers Photo