QUESTIONS AND ANSWERS
“He that questioneth much shall learn MUCH”—BACON
NOTE —Readers of FIRE AND WATER ENGINEERING are invited to send in questions, which will be answered in the order in which they are received. Names are omitted from questions unless otherwise specified.
Effect of Smoke on Firemen
To the Editor:
As I expect to be appointed a fireman very shortly, I would appreciate your trouble if you would answer the following through your magazine: Why is it that some firemen can take immense quantities of smoke without severely hindering them, while others entering small fires are seized with spells of coughing at once, which interferes with their work? How can the latter be overcome? Thanking you in advance for any information you may give me, I am, Respectfully yours, New York, N. Y., April 4, 1921. J. B.
Answer: It is likely you will find, if you observe closely, that the large majority of the men who suffer from smoke as you describe are either new men in the department or men who have had little experience with smoke. It is a fact that firemen after years of service will become accustomed to smoke, and some of the older firemen can remain in an atmosphere laden with smoke for an astonishing length of time. Not only that, but firemen who have been in active service a long time can often taste illuminating gas in a heavy smoke atmosphere, showing that they are practically immune from effects of smoke. Sensitiveness to smoke effects can probably best be overcome by frequent exposure to it.
Chlorate of Potash, Dynamite, Etc.
To the Editor:
I am taking the liberty of asking you a few questions which I can find no answers to in any books which I have at hand now. Would consider it a great favor if you would answer the same.
- While inspecting buildings you come across kegs containing chlorate of potash. What would you do? If building was on fire, would you put water on them?
- What is meant by dynamite in its commercial form?
- What are the two kinds of arson?
- How would you extinguish a fire in a garage?
- How would you extinguish a fire in a building containing carbonic acid gas tanks?
Trusting to receive an early reply, I remain Very truly yours, W. W. E. Lynn, Mass., March 7, 1921.
Answer: 1. By chlorate of potash it is assumed you refer to chlorate of potassium, “potash” itself being potassium carbonate. Past experience has frequently demonstrated the dangerous instability of this substance (chlorate of potassium), and its liability to bring about explosion or fire under seemingly slight provocation. It carries a large percentage of loosely combined oxygen content, and while it is generally assumed that pure chlorates are not inherently of an explosive nature, they are known to become so when in contact with organic matter and other substances; when subjected to the influence of friction, shock (as in crushing the hard lumps), concussion and percussion, and when heated to about 400 degrees Centigrade (752 degrees F.) through the liberation of oxygen, which sometimes occurs in a violently explosive manner. Even, it by chance, explosion does ensue from the ignition of the chlorate, the oxygen liberated serves to promote rapid combustion of intermixed organic matter and of volatiles. Potassium chlorate is usually packed in small hardwood kegs, iron hooped and paper lined, and of a capacity of about 100 pounds each; observation as to methods of handling and storage evidenced the fact that the weight of the package and the assumed rigidity of its construction serves to induce carelessness in handling, with the average result that the shock and jar due to rough usage develops defects in the package through which more or less of the material escapes and is scattered over the floor, thus presenting ideal conditions for ignition from its being mixed with dust from abraded floors; friction, due to contact with workmen’s shoes, or a shock due to the forceful deposit of the iron rimmed keg into this mixture of wood dust and chlorate crystals serving perfectly to complete the mechanical combination productive of combustion. A peculiar and interesting incident showing the extreme sensitiveness and instability of chlorate of potassium has been given by F. M. Griswold, special inspector of the Home Insurance Company, New York, where the provoking cause is attributed to mild friction between the tablets wrapped in paper and a penknife, carried together in the pocket of a man’s clothing; supposedly, the jar incident to sitting down caused contact between the knife and the tablets, which became ignited and the man seriously burned before his clothing could be removed. As mentioned before, when chlorates become ignited large volumes of oxygen are liberated, which adds to the rapidity and intensity of the flame, and the heat thus generated is liable to raise the temperature of contiguous substances to the point at which their volatile and combustible vapors or gases are freely given off and add to the intensity of combustion, and through combination with the oxygen, induce violent explosion; a like result would ensue through contact with charred or carbonized organic matter, such as wood, textile fabrics and the like falling into or upon the mass of heated chlorate.
Now, to directly answer your first question; if the building were of considerable size and containing a number of occupants, and the chlorate was present in large quantity, it should be ordered removed to a separate building where it can be stored in a clean place. Care must be taken that none of the material sifts out upon the floor, and that the containers are placed as remote as possible from artificial heat, such as steam pipes, flues, etc. If the barrels are thoroughly tight and the floors clean, there is little danger in connection with storage of this material, provided it be kept in a cool place. If a building in which chlorate of potassium was stored took fire, it would be very necessary to play streams on the kegs to keep their temperature down.
2. By dynamite in its commercial form is meant a mixture of nitro-glycerine mixed with earth, sawdust or other binder, and shaped into sticks which are wrapped in oiled paper. There are, of course, different grades of commercial dynamite, depending upon the proportion of nitroglycerine to earth (or binder).
3. Pyromania, or craze to see fire, and deliberate setting of fire to attain an object, such as insurance, or revenge.
4. If the fire is incipient, carbon-tetrachloride or foam extinguishers are very effective. Should there be small pools of oil afire, sand or earth are best to use on them. But if the fire has gained headway, as is usually the case, and there are a number of cars in the garage, then you are confronted with a difficult problem. The oil-soaked condition of the floors, the presence of gasoline, oily rags and waste, as well as the combustible part of the automobiles all make for a speedy spread of the fire. There is little to do except endeavor to flood out the fire, ventilating, for instance, in the front end. Keep streams from carrying water into open oil containers if possible, and wet down such gasoline or oil containers to keep the temperature as low as feasible.
5. The greatest danger from carbonic acid gas tanks at fires is the danger of their exploding when heated, due to the increasing of gas pressure with increasing temperature. The gas itself is an excellent fire extinguisher. If the tanks are of approved design they will likely go through the fire without exploding. But in a fire involving carbonic acid gas tanks, charged, it is a safe procedure to wet down the tanks frequently to keep the pressure from rising to a dangerous point. This is the only precaution necessary, in addition to keeping a little ways off in case any of them should burst.
New York State Laws Relative to Duties of Fire Chiefs
To the Editor:
Will you kindly inform me if you know of any state laws requiring the performance of certain duties by a fire chief in the state of New York. Thanking you in advance, I am Very truly yours, Watertown, N. Y. G. W. E.
Answer: Relative to the above the following information has been furnished by the secretary of the New York State Fire Chiefs’ Association, Henry R. Yates, chief of the Schenectady, N. Y., fire department: “Under the old fire marshal department, which has now been abolished, the chiefs of fire departments of cities, towns and villages throughout the state were ex-officio assistant fire marshals; but when that office went out of existence that particular law went out also. I do not know of any law now in existence that has any jurisdiction over chiefs of the fire departments.
Water Pressure and Daily Consumption
To the Editor:
For very many years the City of Greenville, Miss., maintained a pumping pressure of 60 lbs. on their water mains. The plant has been installed about twenty-four years, and while many extensions have been made, but few repairs or renewals have been taken care of. Result, of course, you can readily imagine. House plumbing is defective, especially in the size of service lines, most of which are one-half inch galvanized iron, or five-eighths lead. The country is level, there being no elevations of more than two or three feet, so that the amount of pressure required is practically confined to two-story houses. Until about the first of April, pressure for fighting fire will be furnished through the domestic distribution mains of the city, at a pressure of from 80 to 135 lbs., which, of course, makes many leaks, and does great damage to the fixtures in private residences. The Superintendent, in attempting to reduce the pressure to what would be adequate for the purposes here, that is 30 lbs., has met with great opposition, on account of the difficulty of a large number of consumers in obtaining an ample supply of water through their defective plumbing and fixtures. The Water Department is governed through a Superintendent by a Water Committee, composed of three members of council, and this committee is particularly anxious to obtain information in regard to cities and towns of approximately the same size as Greenville, and with about the same local conditions, the population being approximately 12.000. If convenient to you, will you kindly let me have information regarding pumping pressure and daily consumption of cities similar to Greenville.
Your favor will be greatly appreciated.
Yours very truly,
C. W. H.
Greenville. Miss., Jan. 24, 1921.
Nozzle Pressures on Sixth and Seventh Floors
To the Editor:
Will you work out the following problem in FIRE AND WATER ENGINEERING:
There is a building 150 feet high; size 120 by 120 feet. Fire occurs on the sixth floor. Two lines are run from engine to standpipe, 150 feet in each line, with engine pressure at 180 pounds. Two and one-half-inch hose is used throughout. One line, two sections long, is working on the sixth floor, and a similar line on the seventh floor, 1 1/4-inch nozzles being used on both lines. The standpipe is 3 inches in diameter.
Milwaukee, Wis., Feb. 28, 1921. W. C.
Answer: The steps in the solution are as follows: Consider the two lines on sixth and seventh floors as a single combined line with a nozzle the equivalent of the two 1 1/4-inch tips. A floor height is taken at 11 feet; or 55 feet for sixth floor and 66 feet for seventh floor. Average height of two lines from ground = (55+66) / 2 = 60 1/2 feet.
Two 100-foot parallel lines of 2 1/2-inch hose equal to single line of 2 1/2-inch hose 100=36=27.8 feet in length. 60 1/2 feet of 3-inch standpipe=60 1/2/7-2.6=23.3 feet of 2 1/2-inch hose. Two parallel 150-foot lines of 2 1/2-inch hose =150/3.6=42.8 ft. of singfle 2 1/2-inch hose. Or the entire layout may be considered as a single line of 2 1/2-inch hose 27.8+23.3+48.8=100 ft. approximately in length equipped with a 1 3/4-inch tip. Average back pressure due to elevation of nozzles= 60 1/2 x 0.434= 26.3 pounds.
Effective pressure at engine= 180—26.3=153.7 pounds. Engine Pressure
Nozzle pressure =—
= 153.7 153.7
— = 52.7 lbs.
Pressure at nozzle on seventh floor =52.7+ (5 1/2 x 0.434) =60.1 lbs.
Pressure at nozzle on sixth floor =52.7— (5 1/2 x 0.434)=55.3 lbs.