Qestions and Answers

Qestions and Answers

NOTE;—Readers are invited to send in questions, which will be answered in the order received. Names are omitted from questions unless otherwise specified

Poisonous Gases and Tank Discharge

To the Editor:

I recently read in FIRE ENGINEERING an account of Cleveland Clinic Hospital fire wherein it was stated that _____itrogen dioxide was the cause of death of many of the persons who lost their lives at that disaster.

Question 1. Does celluloid when decomposing always give off nitrogen dioxide gas?

Question 2. Please give a list of poisonous gases that may arise in the event of a fire. Also explosive gases.

Question 3. Is my solution of the following problem, as given below, correct?

A tank of water 20 feet in diameter, and 20 feet high, is filled to the top. How long will it take to empty the same through a 2 1/2-inch outlet wide open, communicating directly to a pipe which terminates four feet above the ground. The tank is set on uprights 60 feet above the ground.

The way I figure it out is as follows:

Height of top of water above outlet is 60 — 4 or 56 feet. Add to this the 20 foot depth of water and we get 76 feet as the height of the surface of the water above the outlet.

Back pressure created by this head is 76 x .434 or 32.984, or 33 pounds approximately. This is the pressure at the outlet, when the outlet is first opened.

Contents in cubic feet equals 20 x 20 x .78.54 x 20 or 6283.2 cubic feet. Multiply this figure by the number of gallons in a cubic foot, namely, 7.481, and we get the total contents as 47,000 gallons approximately.

The discharge from the 2 1/2-inch outlet is secured by the following means:

Discharge equals .80 x diameter x diameter x 30 x square root of pressure or .80 x 2.5 x 2.5 x 30 x 5.7.

This gives approximately 855 gallons per minute discharge.

Dividing the total contents of the tank, 47,000 by 855, we get approximately 55 minutes, the time required to empty the tank.

This answer would be correct, so far as I know, if the head remained constant, but every foot drop in the tank decreases the pressure at the outlet. This is the part of the question on which I would like definite information.

Question 4. Please give me a list of volatile liquids and their flash points.

Question 5. Please give me what information you can on this question: I understand how to find friction loss and change 3-inch hose to 2 1/2-inch, but I have never seen any method whereby I can determine the friction loss on 3-inch hose having 2 1/2-inch couplings.

Respectfullv yours,

E. W. J.

Answer 1. Yes, when ordinary celluloid is decomposed nitrogen dioxide gas is always present. The quantity of the gas will, of course, depend upon the process of decomposition as well as the particular ingredients in the celluloid which is decomposed. Compositions of celluloid vary widely, and products of decomposition likewise vary considerably, depending upon the amount of air present.

Answer 2. It is presumed you have reference to any fire and not alone to celluloid fire. In such case, the gases thrown off depend upon the materials burning. It would be impossible to list all of the gases generated at fires of different types. This much may be said, however, that carbon dioxide is present at all fires and carbon monoxide at a great many.

Answer 3. Just as you suggest, an error creeps in where you consider head of water constant. A very fair approximation of accurate results would be secured by taking the average height of water in the tank, 10 feet. In other words, we would divide the 20 by 2 to get the average height and this figure, 10, would be added to the 56 feet to give us 66 feet instead of 76, as used in your calculation. Using this particular head, the results you would secure would be very close to 100% accurate. When the tank is full we have 20 feet to consider, whereas when it is empty we have no depth. Adding the 20 to 0, we get 20, which, divided by 2 for the average, gives us 10 feet depth.

Answer 4. You are referred to the “Condensed Chemical Dictionary,” published by the Chemical Catalog Company of New York, for this information. Space here would not permit listing all of the different types of inflammable volatiles and their flash points.

Answer 5. An approximate method which will your purpose in finding friction loss of 3-inch hose with 2 1/2-inch couplings is to find friction loss for a similar length of 3-inch hose with 3-inch couplings, and when you have secured this friction loss, add 10% to it. In other words, suppose the friction loss in a certain length of 3-inch hose were 40 pounds. To find the friction loss in the same length of hose with 2 1/2-inch couplings we would add 10% of 40 or 4 pounds to the 40 pounds, giving us 44 pounds as the friction loss in the length of 3-inch hose with 2 1/2-inch couplings. This method gives you results which are slightly greater than you would secure by test with moderate flows in hose lines. Nevertheless, it is a method which plays safe.

Sulphuric and Nitric Acids

To the Editor:

Will you please answer the following question as soon as possible? Is nitric or sulphuric acid explosive or inflammable?

What effect have they on a person when liberated under fire?

What is the proper method to neutralize these acids when involved in fire?

Yours very truly,

J. S. M.

Answer: Nitric and sulphuric acid are neither explosive nor inflammable.

Both are highly corrosive; that is, produce a searing effect on the lining of the lungs, when inhaled. Nitric acid, in particular, is extremely hazardous from this standpoint, the fumes thereof frequently causing death when inhaled in sufficient quantity. Sulphuric acid, on the other hand, while not quite as deadly, presents a life hazard where it is encountered at a fire.

Nitric acid fumes are hard to detect when mixed with smoke, and hence are more dangerous than those from sulphuric acid.

Either nitric or sulphuric acid may be neutralized when present in small quantities by the use of soda, thrown directly in the acid.

When present in large quantities, about the only thing that can be done to reduce danger thereof is to drench with water.

Nitric and fuming sulphuric acids will ignite combustible materials with which they come in contact, but when diluted with water, this possibility is eliminated.

Bode, Ia., Buys Apparatus—The town of Bode and eighty farmers living within a radius of seven miles of the town have contributed to the purchase of fire apparatus.

Two Pumpers Housed at Norristown, Pa.—Two new pumpers have been officially placed in service at Norristown, Pa.




“He that questioneth much shall learn much”—BACON

NOTE—Readers of FIRE ENGINEERING are invited to send in questions, which will be answered in the order received. Names are omitted from questions unless otherwise specified.

Ammonia Hazard at Open Flame

To the Editor:

The question has come up in our department as to the hazards, if any, that are encountered by having an ammonia refrigeration plant and the hot water boiler, with an open flame in the same room. This condition exists in one of our local hotels.

Your courtesy in answering the above will be appreciated.

Very truly yours,

B. J.

Answer: If leaks of ammonia can be absolutely prohibited in the furnace room, there will be no hazard in connection with having the ammonia refrigeration plant and the open flame of the hot water boiler in the same room.

But when you recall that ammonia leaks are always occurring, and that ammonia fumes when mixed with proper proportions of air produce an explosive mixture, I think that you will appreciate that permitting the refrigerating plant and the open gas flame in the same room is indeed dangerous.

It is true that the number of ammonia gas explosions is small, but records show that where they have occurred the damage has been great.

The Morris Packing Company explosion in Chicago may be cited as an example. At this explosion an entire wall was blown out of a building and killed the fire chief and 22 of his men. You are justified in demanding the remedying of the conditon in the plant you describe through the segregation of the open flame and the ammonia apparatus.

Qualifications of Fire Chief

To the Editor:

Below are several questions which I would appreciate having you answer for me.

Question 1. If you were to pick a chief of a fire department what kind of material would you look for?

2. If you were appointed chief of a fire department where there has never been any discipline, and the personnel and morale of the department poor, what would be the first thing to do?

3. How would you handle the various duties in connection with the office of fire chief in order to make good; by such duties are meant inspections, fire hazards, reports, etc.

4. If you were to examine a number of applicants for the position of chief, how would you go about it ? Would you have a number of questions to ask them about things that a fire chief should know? What questions would you ask?

Very truly yours,

F. K. F.

Answer 1. The questions you have asked are in indeed hard, if not impossible, to answer in view of the fact that the qualifications for chief for different size cities vary as widely as do the population of the cities.

We will, however, attempt to offer answers to those questions which can be readily answered.

The qualifications of the man chosen should include the following : Experience in handling men; experience in fire depart-

ment work; a good physique; enthusiasm in the type of work to be assigned to him.

Answer 2. Prepare a set of rules and regulations governing the men of the department, and covering their deportment, if such rules and regulations are not already on hand. Have these rules and regulations adopted by the governing body of your city, and make sure that the rules and regulations as passed upon give you the authority to enforce them. With this authority you are then in a position to see that discipline is administered in the proper manner.

Rules and regulations should be patterned after those of one of your neighboring departments which has had experience in organizing and disciplining its fire force.

Just as soon as they are in effect then it is up to you to see that thev are rigidly observed. You should be prepared to prefer charges against members of the department who violate these rules. One or two such charges will quickly let the force know that you are in earnest and will result in good all the way around. Firemen, you will find, appreciate fair play and are always willing to co-operate with you to the limit. On the other hand absolute fairness must be shown—there must be no partiality.

Answer 3. This is a big order. Probably the first thing to do would be to post yourself on the fire hazards in your city. Determine what features about the various industries and establishments are hazardous from a fire standpoint. Make your inspections periodically, carrying out the main inspections of the larger plants yourself and to the smaller establishments you may delegate your assistant, or rank and file of the department to do the work, after fully instructing them as to what their duties will be. Greater results can be secured through thorough inspection than through fire fighting. In other words, preventing fires is a better way of reducing fire loss other than fighting fires once they have gained a start.

Handle your department efficiently, and inform yourself on up-to-date methods of fire fighting operations so that you will be in a positon to lead and direct your men.

Bear in mind that the duties of the fire department include the saving of life and property from fire. These points should be foremost in your mind at all times and all efforts must be directed toward accomplishing results along these lines.

Answer 4. The usual method of examining applicants for the position of chief of the department is through written examination. This is fair as the various candidates will have equal opportunity of making the grade if they are properly fitted for the work.

Examinations in the form of an interview are seldom satisfactory for they cannot be considered as impartial as the written examination where the names of the candidates are not disclosed until after the papers have been marked.

Hence the first thing that would be done would be to call the examination for a definite date and submit the various candidates to a written examination.

The questions to be asked would include topics showing the candidates’ fitness for the work. These must necessarily entail questoins on operations at fires, methods of extinguishing, hazards, methods of making inspections, governing the department. and finally questions showing the candidate’s familiarity with laws and ordinances including rules arid regulations if such are in force.

As to the questions to be asked, this would be impossible to state unless a thorough knowledge of the city and the state of organization of the fire department as well as its equipment is known.

The above, you will appreciate, is only an outline. It is as noted in the answers—impossible to give you specific questions which might be asked.

Possibly the best advice that could be given you would be that you secure some of the standard books on fire department matters, such as “Questions & Answers for Lieutenant & Captain,” etc. Study these books and you will find it will take you a very short time to become familiar with the field and secure the necessary knowledge for successfully passing any examination which you might meet.

Buffalo Promotional Questions

To the Editor:

Would you please favor me with answers to the following questions? I am a Buffalo fireman and if possible would like to receive an early reply to the same. We have been subscribers to FIRF. ENGINEERING for some time, but cannot find the answers to these questions.

Thanking you for your prompt attention, I am.

Yours very truly,

C. W.

Fire Dept., Buffalo, N. Y.

Question 1 : Name a device for torn hose, while working at a fire.

2. Could a gas well fire be extinguished with hose streams? Answer Yes or No.

3. Is soda and acid tank lined with copper?

4. Can a soda and acid extinguisher with a loose stopple be successfully used on an auto fire truck? Answer Yes or No.

5. Would a stream of water be nearly as effective as a stream from soda and acid on a fire in the open?

6. Which is a better coating for ladders, paint or varnish?

7. Two lines of hose—one 3 1/2 single line—the other 2 1/2″ siamesed. which will have higher pressure at the nozzle?

8. Is there any danger from slacking lime in open space? Answer Yes or No.

9. Are there any hose nozzles that develop a discharge efficiency as high as 95%? What are they?

10. Water thrown on intense fire, is water actually vaporized? Answer Yes or No.

11. Will force of stream striking a steel beam in a fire bend the beam? Answer Yes or No.

12. Why does fire spread upward?

13. Name three methods of stopping fire. Could standpipes, sprinkler systems and pressure tanks be named?

14. How are iron and steel affected by fire? Does it lose temper and warp and soften?

15. What happens to gas when heated—does it ignite and explode?

16. Name three agencies that will spread fire—will gasoline, oils and chemicals?

17. In a six story building, which is most dangerous to fight; fires in basement, first floor, third floor or cockloft?

18. Where will fire travel unseen?

19. Water thrown on fire in warehouse—where there are bales of clothing, granite utensils, furniture, crates, dishes, which would you have to be most careful of?

20. Can a New York hose nozzle be called a hose pipe?

Answer 1. A hose jacket is a device used for mending leaky or torn hose at a fire.

2. Yes.

3. Small extinguisher tanks are usually made of copper entirely. The larger tanks are usually of seamless, drawn steel, and are lead or tin covered on the inside.

4. No.

5. Where the diameter of the soda and acid stream and the water stream are the same, their effectiveness is precisely the same on open fires.

6. Varnish makes a better coating for ladders than paint for it does not conceal any defects in the wood which may exist or which may develop. Modern varnishes are much more durable and will stand water and fire exposure better than paint.

7. The layouts to be compared in question 7 are as follows: A single line of 3 1/2″ hose and parallel lines of 2 1/2″ hose, each one supplying the same size tip and each layout being of the same length; that is, the length of the 3 1/2″ hose single line will be exactly the same as the length of parallel 2 1/2″ lines (twice as much 2 1/2 hose being used).

Under these conditions the 3 1/2″ line will have the higher pressure at the nozzle as the friction loss in the 3 1/2″ line is less than in the parallel 2 1/2″ lines.

8. No.

9. Any of the plain hose nozzles develops a discharge efficiency higher than 95%. Special types of nozzles, such as those intended to produce sprays or water screens, frequently fall below 95% discharge efficiency.

10. Yes.

11. No.

12. Fire spreads upward due to the fact that the heated gases and air are lighter than cold gases and air. This is well illustrated in the toy balloon. These balloons may be inflated with air but they will not rise. However, just as soon as the air within them is heated by a torch provided for that purpose, the balloons rise quickly. It is the presence of heat, and the resulting expansion of air and gases by being heated, that create the force upward. This force naturally produces a motion of the gases and heated air upward with the result that fire spreads in the same direction.

13. Methods of stopping fire include: Smothering it; cooling the materials down to a point below the reignition point; and blowing the fire out by concussion (snuffing it out).

Standpipes, sprinkler systems and pressure tanks could not be named as three methods for they are devices rather than methods.

They all extinguish fire in the same manner, namely, smothering or cooling to a point below ignition point.

14. Iron and steel lose their temper and warp upon being heated and cooled. Losing of temper is particularly the case where they are cooled gradually. When suddenly cooled after being heated, iron and steel may become even harder due to the process of tempering.

15. The answer to this question depends upon whether or not the gas is in contact with air or whether it is closely confined by itself; also it depends upon the mixture.

There arc practically no elementary gases encountered in fire department operations which will burn by themselves. They all acquire the presence of oxygen. If, therefore, they are confined in containers and kept isolated from the air surrounding them the usual result of heating is an increase in pressure due to their tendency to expand upon heating. As long as the container withholds the pressure, there is neither ignition or explosion. If, however, the container gives way and the gases come in contact with air and at a temperature equal to or higher than their ignition point, they may ignite and explode.

Gases when heated in the presence of air, if these gases are inflammable, may burn very rapidly or create the so-called explosion. If confined in the presence of air and heated to a point equal to or above their ignition point they may ignite and expand, doing tremendous damage.

16. The three methods by which fire may spread are: convection, conduction, and radiation. However, these methods may not be classed as agencies; if it is assumed that by “agencies” are meant materials or structural conditions wdiich promote spread of fire, then under this assumption the following three agencies are cited; vertical shafts, such as in partitions; inflammable gases; highly inflammable liquids.

17. Of danger to property, fire in the cockloft may be considered the most serious, it is hard to get at, it will spread rapidly, and the surrounding materials are usually in a much more inflammable state than where they are encountered on other floors.

But from the standpoint of hazard to the men operating at the fire, possibly the fire in the basement is the more dangerous. At least records show that more men are knocked out at basement fires than at any other type of fire. This is due to the difficulty in ventilating and the fact that men are forced to work at close quarters.

Fire department operations are now such that fires occurring on the second, third, or fourth floors of buildings where there are floors both above and below are quickly brought under control due to the practice of covering exposures, providing ventilation and getting streams in operation.

The cock loft fire offers many difficulties in addition to those encountered on other floors of buildings due to the inconvenience in getting to the roof and the danger of men operating on the roof when fire has gained headway in the cock loft. Then, too, the absence of openings through which streams can be directed makes a fire in the cock loft one which is hard to bring under control.

On the other hand a fire in the basement of a building outside of the danger to the firemen, is quite convenient to handle. Lines can be quickly stretched in and exposures covered.

Of course if the basement is occupied by a highly combustible occupancy then the story is a different one. However, in making a comparison of this sort it is necessary to assume conditions at least similar.

18. Fire will travel unseen up partitions and through other vertical, enclosed, ducts.

19. If the fire were a minor one and the fire damage would not amount to much nor would the water damage, then the streams should be kept away from bales of clothing and the dishes.

If the fire, on the other hand, was gaining headway and was apt to involve a large part of the materials on the floor then the clothing would be the articles from which the streams should be kept away.

Dishes in warehouses are usually stored in crates, well packed with excelsior. In this case no attention need be given them as they are not subject to injury. On the other hand the clothing is always subject to damage from water and for that reason streams of water should be kept away from it.

The next in order would be furniture. Granite utensils, in crates, would not need such great care at fires.

20. The designation “New York Hose Nozzle” is very vague. It may apply to the bent pipe used for work in partitions, it may apply to the New York type of shut-off and it may also apply to the long or short plain nozzles. Some text books refer to it as being the bent pipe while others take it to mean the shut-off, or straight nozzle.

The long type of New York Nozzle may be called a hose pipe though the short type should be classed as a plain nozzle.