[How to Fight Fire Bombs]
[From the U.S. Government Publishing Office, www.gpo.gov]

HOW TO FIGHT FIRE BOMBS
This leaflet is a reprint of instructions given in the memorandum July 24, 1942, plus Operations Letter No. 80, issued October 28, 19 Because Operations Letter No. 80 modifies the instructions given in memorandum of July 24, 1942, the two documents should be r
together.
OFFICE OF CIVILIAN DEFENSE
WASHINGTON, D. C.
OPERATIONS LETTER NO. 80	October 28, 1942.
SUBJECT: New Types of Enemy Bombs, Incendiary and Anti-Personnel
1.	The enemy recently has employed new types of bomb—both large incendiaries and the usual small type with a more powerful explosive charge set off by a time fuze. Experience with these bombs in other countries and our own study of the techniques developed to cope with them make it clear (a) that fire continues to be a most important weapon and (b) that, against fire, water is still the best weapon. When heavier, delayed-action explosive charges are added, they are primarily intended to hold off attack on the fire until it has gained dangerous headway.
2.	New types of enemy incendiary and anti-personnel bombs are:
a.	The usual 2.2-pound fire bomb, with an extension of the nose containing a larger explosive charge. The total weight is increased to 5 pounds. The bomb is 17 inches long without its tail, or about 21 inches long over-all. The incendiary section of the bomb ignites upon landing, but the explosive charge may go off at any time up to 7 minutes later. It would be possible to increase this lapse of time without major alteration of design, so that there can be little
dependence upon the present time interval. The explosive part may become detached, but this does not lessen its effectiveness. This type of bomb has been employed by the Germans.
b.	A combination incendiary and high explosive bomb, in a casing the same size and shape as the 110-pound high explosive bomb (about 30 inches long and 8 inches in diameter). On impact it throws out 60 small metal containers with thermit-type filling and six larger tumbler-shaped fire pots containing a magnesium-type filling which is preignited. Almost immediately after ejecting the incendiary units, a 12-pound charge of TNT in the nose of the bomb explodes.
c.	A phosphorus-oil bomb in a casing similar to that of the 110-pound high explosive bomb, but containing only the usual type of fuze to split the casing open on impact and scatter its sticky liquid contents. The contents ignite spontaneously because of the phosphorus. The phosphorus may be extinguished by water but will break into fire again if allowed to become dry.
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d.	A Japanese bomb weighing about 110 pounds and. containing, besides a quantity of thermit, a considerable number of rectangular-shaped rubber-impregnated incendiary pellets which scatter widely and start a substantial number of small fires which may be attacked immediately.
3.	The most effective method of attacking fires caused by these bombs is the same as was outlined in revised instructions last July concerning the ordinary magnesium-thermit 'type of fire bomb—a jet or direct stream of water. The small fire bomb without explosive charge is still the most widely used of all types, exceptby the Japanese. If bombs fall where they cannot start fire and cannot be seen from the air, they should be left to burn themselves out, but elsewhere they must be attacked. The bombs without heavy explosive charges or those which explode upon impact present only the problem of dealing with fire and thus require no additional instructions.
4.	The small fire bomb with delayed-action explosive charge requires a revision of instructions concerning the types of cover that provide full protection from the blast.
a.	A brick wall 4% inches thick is considered full protection against the explosive charge now being used with a time fuze in small magnesium bombs. In walls built of outside bricks of the best quality, a 3-inch thickness will prevent penetration. Lath and plaster walls, wooden doors, tables or chairs do not offer full protection from the explosion of this charge. Personal risk may be greatly reduced by assuming a crouching or prone position behind the best available cover.
b.	Where fires are likely to spread rapidly—as in congested districts and where there is relatively little fireproof construction—even bombs which may explode should be attacked promptly from behind the best available cover. Care should be exercised to expose no more than one hand while playing a stream of water on the area surrounding
unexploded bombs, but this risk is considered necessary where unchecked fires might start a conflagration. Water may be thrown from a small (or 1 pint) container, dipping from a large container, if a pump has not arrived. Although less efficient than a jet of water, this method may permit the wetting of inflammable material within range of the bomb. Water should be thrown from a crouching position from the cover of a solid wall, as in other methods. In this case the water need not be thrown on the bomb itself.
c.	Use of a jet of water enables the operator to work at a much greater distance than the “short range” methods employing sand, other smothering agents, or a spray of water. Sand in the form of bags or mats cannot be depended upon, because these bombs, upon explosion, have a greater fragmentation effect than the explosive incendiary bombs formerly used. The public should be warned against the use of all such smothering agents as “bomb extinguishing” powders: also against such devices as scoops, grabs, and snuffers. They are entirely without merit and may endanger the lives of persons who depend upon them. The use of spray and sand is no longer recommended because the possibility of fragmentation makes it too dangerous to appproach the bomb sufficiently close to apply them.
d.	The new types of bombs increase the importance of storing water in the home, as heavier explosive charges and larger bombs make it even more hazardous to depend upon normal water service. (Containers previously used for sand should now, if possible, be used for water.) It should also be pointed out that water storage tanks used in connection with water heaters, hot water or steam furnaces, or other home equipment may be useful, if they can be drained quickly. The location of the drain valve should be marked so that it can be found promptly in the dark.
5.	A thorough search of the premises should be made after every raid. Any unexploded bombs should be reported
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promptly to the bomb reconnaissance agent for inspection. Where phos-phorus-oil bombs have been used, all areas touched by the oil should be kept wet until proper authorities have examined them to see whether phosphorus is present. Physical contact with fragments of such a bomb or any ground or equipment splashed with the liquid should be avoided.
6.	These developments in enemy air attack mean that the forces of workers rained to deal with all types of bombs
must be increased as rapidly as possible. Plans for recruitment and training of such an expanded force may be expected at an early date. Methods of attack may be changed frequently. Such changes may be even more rapid as our enemies desperately seek to incite fear in civilian ranks, but they should serve only to intensify our efforts to develop a large, alert, and well-trained force that is ready for any challenge.
JAMES M. LANDIS,
Director.
OFFICE OF CIVILIAN DEFENSE
WASHINGTON, D. C.
July 24, 1942.
MEMORANDUM REGARDING REVISION
OF OCD INSTRUCTIONS
FOR COMBATING INCENDIARY BOMBS
More extensive practical air raid experience abroad and exhaustive recent tests conducted in this country have made it clear that certain changes should be made in the OCD instructions covering methods to be followed in dealing with the 2-pound magnesium fire bomb. This revision is considered desirable because:
1.	Speed in disposing of fire bombs is now known to be essential for a successful defense against incendiary fires. Several bombs commonly fall in a single home or other occupancy, and if too much time is spent in disposing of one bomb, others may be given the opportunity of starting uncontrollable fires. The quickest possible way of dealing with a bomb is by using a jet of water, since the jet does, in a matter of seconds, the work that requires several minutes when the spray technique is used. By using a jet, several bombs lying nearby can be dealt with before any of them has time to do material damage.
2.	Immediate attack upon the bomb
may prevent the action of a burster attachment, thus removing its danger to the person fighting the bomb.
3.	By using the jet, the operator can attack the bomb quickly, and the chance of a fire being started under the bomb is substantially reduced.
4.	The undue emphasis thus far placed upon the bomb has directed the attention and thinking of civilians to the bomb, and not to the real danger—the fire started by the bomb.
5.	The effect of the reaction that takes place when water strikes burning magnesium has been misinterpreted to consist of an explosion which may cause personal injury and increase the fire hazard. This exaggerated conception of the “terrors” of the bomb has instilled unjustified fear, which must be changed to a feeling of confidence on the part of civilians in their ability to cope with bombs. Due to the directional force of the jet, the scattering of the metallic fragments is away from the operator, and, therefore, his personal
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danger is minimized. Moreover, the operator can stand farther away from the bomb when using a jet than he can when using the spray.
6.	The amount of water required to dispose of a bomb by the jet technique is much less than half that needed for the spray treatment. Under certain circumstances, this economy of water may be of vital importance.
The general tenor of the revised instructions is as follows, though the exact wording will be changed as circumstances require:
In dealing with fire bombs, it is important to remember that the fire started by the bomb, and not the bomb itself, is the real danger. Hence, never devote attention to the bomb at the risk of allowing the fire to get beyond control.
Water is the best agent for controlling both the fire started by the bomb and the bomb itself. It is best applied to both in the form of a jet or solid stream, and not in the form of a spray. With a jet of water supplied by a suitable device, such as a garden hose, stirrup pump, pump tank, or other water-type extinguisher, the bomb can be quickly put out of action, leaving the operator free to deal with fires started by the bomb.
To put the bomb out of action, shoot the water jet right at the bomb. Don’t be frightened by the momentary flash of light and scattering of metal which will occur when the jet hits a burning bomb. An instant later nothing is left but scattered fragments and an unburned part of the bomb. These, together with the fires that have been started, are easily quenched with the jet.
The scattering of the bomb may also. forestall the action of a burster charge which may be attached to the bomb. The use of the jet permits the operator to stand well away from the bomb, but for increased safety, some personal protection, such as that provided by an ash can lid, small chair, or a wet blanket, is desirable.
In certain unusual situations, where there are concentrations of highly flammable materials, it may be essential to avoid scattering burning metal. Use a spray on the bomb only in such instances. While water is by far the best weapon for use on bombs, there are two situations where sand will be useful: (1) If the bomb is where it is not likely to start a fire, sand may be dropped upon it, preferably contained in a sand bag; (2) if no water is available, the bucket-and-shovel sand technique may be used.
When all fires are out, be absolutely sure that there are no smouldering remains that might flare up again.
The revisions recommended here are supported by the following documentary material:
A. Report on series of tests conducted by the Chemical Warfare Service, U. S. Army, at the War Department Civilian Protection School, University of Maryland.
These tests were concerned with the application of a solid jet of water on a magnesium incendiary bomb. • The summary of the tests, the conclusions reached, and the recommendations made, are as follows:
SUMMARY
1.	Scattering of the molten magnesium occurred, producing small burning particles which were easily burned out.
2.	Resulting fires on curtains were immediately controlled without the necessity of changing the nozzle opening.
3.	The time required to control both bomb and resulting fires varied within the limits of 22 and 40% seconds, with a median value of 26 seconds.
4.	The quantity of water required varied from 4 to 10 quarts, with a median value of 5 quarts.
5.	Charring of the floor surface was very superficial on the board used, and penetration occurred in only one instance, to a* very slight degree.
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CONCLUSION
1.	A jet of water can be used to control a magnesium incendiary bomb and the resulting fires in nearby combustible materials. No apparent danger existed for an unprotected operator, and even less danger would exist when protective devices such as a shield or blanket are employed.
2.	This method .requires very little time and water to accomplish the purpose.
RECOMMENDED
1.	That the incendiary bomb be attacked with a solid jet of water.
2.	That the operator stand more than eight feet away from the bomb.
3.	That instruction be continued in regard to removing inflammable material from rooms and attic spaces.
B.	Excerpts from the Report of Civil Defense Research Committee, British Ministry of Home Security, Sub-Committee F., Memorandum On Instructions For Attacking the Kilo Magnesium Bomb.
“Experience of kilo magnesium bombs under raid conditions has indicated that official instructions should be reexamined. After careful deliberation the Incendiary Bombs Committee agreed to the following report which was passed by the Chief Adviser, Research and Experiments, to the Fire Prevention Division. It has now been decided that official recommendations shall be in agreement with this report and that the jet should be used as the normal form of attack on both bomb and fire, while the spray should be reserved for special circumstances in which it would be essential to avoid all scattering of magnesium.
“As the result of a conference, at which representatives of the Ministry of Home Security, Ministry of Supply, Air Ministry, Ministry of Works & Buildings, and the Incendiary Bombs Committee were present, Professor Finch was asked to carry out experiments to discover whether any advantage was to
be obtained by using the jet instead of the spray. The experiments have been carried out and the results, coupled with those of past experience, have revealed the following:
“1. A proportion of the incendiary bombs dropped may be of the explosive type, their object being to deter the fire party on the spot from taking prompt action. The proportion of E. I. Bs. may vary within wide limits.
“2. The outstanding value of the stirrup hand pump as first-aid equipment has been established. It is known, however, that the jet is much more effective than the spray, and it can be used from a greater distance: owing however, to misinterpretation of the official instructions, undue emphasis has been laid on the supposed dangers of the use of the jet on the bomb.
“3. Although, the jet initially causes much scattering of molten magnesium, it has been"shown that as regards danger to personnel owing to protective spheroidal action, the spray of sputtered molten magnesium is practically harmless and will not give rise to burns, unless particles become trapped between skin and clothing. Further, since the fire party is on the spot and the incendiary action of the sputtered magnesium droplets is relatively slight and of a totally different order from that of an undispersed pool of the molten metal, subsidiary fires which canriot be controlled with the stirrup hand pump are not likely to arise from the use of the jet on the bomb.
“4. The density of an I. B. shower can be such that several bombs may lodge simultaneously in a single building of comparatively modest dimensions.
“5. The prospects of successfully dealing with a fire diminish at a rate which is statistically out of all proportion to the age of the fire.
“6. Civilian fighters, in spite of instructions to the contrary, have shown a tendency to attack the more spectacular I. B. display (usually outdoors) rather than to search first for those which have fallen indoors.
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“7. It is understood that the fire party system is still below strength in many places.
As-the result of a careful examination of the above, we recommend that:
“(a) It should be emphasized that every incendiary bomb should be treated as being of the explosive type.
“(b) The bomb should be attacked without delay but from behind cover, remembering that the bomb may explode at any time within the first two minutes of falling; advice should be given as to what constitutes^ cover and the best way of using it.
“(c) The jet of the stirrup pump should be used as the chief method of attack, not only on the fire, but also on the incendiary bomb. The public should be informed as to the little personal danger likely to be experienced from fragments of molten magnesium scattered by the jet. Conditions where the use of the spray is preferable to that of the jet are unusual. Nevertheless, in a shop or store, or room containing highly inflammable materials which happen to be close to the bomb, particularly when the materials are hanging or in dwelling houses with light curtains the use of the spray on the bomb might be advisable.
“(d) The advantages of the jet are that the bomb and fire can be attacked with a greater volume of water and from a greater distance than with the spray, thus allowing a greater choice of effective cover and effecting a saving of time.
“(e) Instructions should be given to fire fighters that they should concentrate first on seeking out and attacking bombs which have fallen where they are likely to cause fire; and that having dealt with one bomb they should look out immediately for the next.
12th January, 1942.”
C.	British Air Raid Precautions Handbook No. 9, Second Edition.
“Hitherto the view has been that in general the spray of the stirrup hand
pump should be used for dealing with the bomb, and that the jet should be used only for extinguishing fire caused by the bomb. The advantage of the spray is that it causes little or no scattering of the molten magnesium of the bomb whereas the jet causes considerable scattering. The jet has an advantage in that it disposes of the bomb more quickly than the spray, but at the time of the issue of the first edition of this Handbook the advantage of the spray was regarded as outweighing that of the jet on the ground that the scattering of molten magnesium might cause personal injuries or spread fire.
“This view has been modified by the following considerations:
“(a) The necessity for speed when a number of bombs fall simultaneously on one building or where numbers of bombs have to be dealt with by a single fire party. Experience has shown that in many cases, in spite of the fact that fire parties have been able to cope with many bombs, the fires caused by others have got out of hand especially when incendiary bombs are dropped in large numbers from containers. Moreover, it has been found that the risk of injury to personnel from molten particles of magnesium scattered by the jet is not great, and would be far more than counterbalanced by the saving of time effected and the risk of a possible conflagration avoided.
“(b) The introduction of the explosive incendiary bomb.
“Every opportunity must be taken to obtain cover when a bomb must be dealt with at once.
“The jet in such cases has advantages over the spray, because being effective from a longer range, the chances of injury from a fragment of steel are much reduced and a greater choice of cover is likely to be available. Further, by freely scattering the molten magnesium and by its cooling action, the water jet may even serve to prevent the explosion of the capsule if the bomb should be of the explosive type.
“Accordingly, in cases where speed is
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the governing factor, or whenever a bomb must be tackled at once with the stirrup hand-pump, the jet should be used instead of the spray. Care should be taken to prevent particles of molten magnesium from lodging between the clothing and the skin. There may be occasions when the spray should be used in preference to the jet, for example, where there is highly inflammable material close by and it would in consequence be dangerous to risk the scattering of molten magnesium.
“If several bombs have fallen in one part of a building those which cannot be tackled at once” with a stirrup handpump should, if possible, be covered with ‘sand-mats’ (see page 25) to prevent the spluttering of the bomb from setting fire to curtains, chair covers, etc., and to keep the fire in check until the bombs can be dealt with.
“But bombs so covered are not extinguished and may burn through the floor into the room below; consequently they must never be left without further attention.”
D.	Draft of New Zealand Fire Precautions Bulletin (title not given):
“The former instruction that a jet must not be directed at a magnesium bomb is now cancelled, in Britain and in New Zealand.
“The present instruction is that a jet of water played directly on the bomb is fully effective in extinguishing it rapidly, notwithstanding that there is a momentary violent reaction from the bomb, which flares into a sheet of white fire.
“Attack bomb and fire resolutely, directing the jet into the fire-heart of the bomb, attending as well to fire in surrounding materials. Here also attack the heart of the fire, not the upper flame.
“And always, if possible, rake out and pick up the bomb, now cooled by the water stream, and drop it into a bucket of water. By rapid extinction danger from the final bursting charge is avoided.
“The jet from a soda-acid extinguisher can be used in the same way as a hose jet.”
UNITED STATES OFFICE OF CIVILIAN DEFENSE
WASHINGTON, D. C.
DECEMBER, 1942
V. S.GOVERNMENT PRINTING OFFICE: IS4Ï
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