FIRE STREAMS AND THEIR HANDLING.
IN a paper with the above heading read by Cyrus R Robinson, of East Concord, N. H., before the recent Massachusetts State Firemen’s association at North Adams, Mass., was shown the importance of the fire stream and its handling, which the writer insisted was the “keynote for either the success or failure of the fireman.” The latter (he said) should be a thorough student in hydraulics; he must know how to produce the best results of streams under different pressures and conditions; he must understand why certain sizes of streams in one fire will prove a complete success, while the same streams and pressures would be the direct means to increase instantly another fire into a conflagration. The stream, then, and its handling is the supreme agent that he must depend upon for his success. What ammunition is to an army, water in its different manipulations is to the fireman. * * *
Passing on to the subject of fire streams, Mr. Robinson stated that the character of the stream produced is in the form of a spray, under a pressure of 100 to 200 pounds or more to the square inch, the streams seldom reaching a distance exceeding forty feet. While the small stream is found most excellent in a fire initsincipient stages, if it were possible to project the same streams into the fire that is reaching into large proportions, even a thousand such streams, the firemen would then simply be furnishing fuel for the flames, and inviting a conflagration in place of subduing the fire. It will be found that inadequate streams lead only to disaster. The commonsaying that the fire is beyond control, simply means that it is beyond control of the sizes of streams then in use. After a careful perusal of this subject it will be seen how afire under certain conditions can be increased, or the same averted by the use of proper tools.
The effect of water thrown on a fire after reaching certain degrees of heat was then adverted to. At 212 degrees water becomes steam, which at 1,470 degrees is turned into water’s two constituent gases, hydrogen and oxygen. The former, when burned separately, is the hottest of all known gases, exploding, when mixed with three-sevenths of its volume of air, and, when incandescent, evolvingsuch an intense heat as to melt almost any known substance. Oxygen, which forms one-third in the composition of water, is the chief support of combustion. Water, when properly applied,is the best means for reducing the heat-units and putting out a fire. But (says Mr. Robinson) fires differ largely in their intensity of heat. They are supposed to be augmented largely from inadequate streams, which are converted into their original gases, or decomposed, and add fuel to the flame. The complete success of the fire company, then, is in meetthe fire with a size of stream as near as possible to drown the fire at once. In this case the whole amount of water is utilized in reducing the temperature, which at once puts the large fire in control, bringing it to a point where smaller streams can then be made available and valuable; or, in other words, every fire company is incomplete without their cannon, or large stream on fires liable to reach into large proportions. A cannon stream for a fire company is just as essential to the fire service us the cannon for an army. The large and long distance streams must shell the large fire, protecting the firemen from heat with their smaller streams as far as possible; by smaller streams I mean from one to one and one-quarter inches.
There is probably no subject pertaining to the fire service so important to be thoroughly understood, and one that firemen generally understand so little, as that of pressure and distances that different sizes of streams can be projected under different pressures. At first thought one might reasonably suppose that the more pressure applied to a given size of nozzle, the greater the distance the stream would reach, and that any increase in size, without any increase of pressure could only be proportionally less in distance.
A knowledge of hydraulics shows that “pressure above a certain point onany size of nozzle produces a result the very opposite.” That increase simply stands for an increase of velocity, and the moment that velocity is increased, it “meets with an added resistance of the air, and begins to ‘strip,’ or, as the firemen call it, ‘will tear itself to pieces’” and fail to reach the same distance as under fifty pounds less pressure. Thus, in the case of a five-eighth inch size stream, “the maximum that this size can be forced perpendicularly in still air under 200 feet head, or eighty-six pounds pressure, is 100 feet.” If the pressure is increased to 130 pounds, the height diminishes to seventy-five feet. By simply increasing the size of nozzles all under the same pressure, the three-quarter-inch reached 116 feet; the one-inch, 137 feet; the one and one-quarter-inch, 150; the one and one-halfinch, 158; the one and three-quarter-inch, 166; the two-inch, 169. From this it will be seen that the same pressure that sends the five eighth-inch 100 feet high sends the two-inch stream sixty-nine feet higher. On the other hand, the 130 pounds that cut down the five-eighth inch stream from 100 feet to 75 feet sends a two-inch stream 280 feet high, or an improvement in perpendicular distance of 155 feet, besides delivering over 900 per cent, larger volume. To carry out this five-eighth-inch still farther: It was found that when 130 pounds pressure was applied, a stream seventy-five feet high was the result; a pressure of forty-three poundsgave the same result in height; and with a pressure of 151 pounds the stream was then reduced to fifty feet high, when twenty-six pounds would have accomplished the same height; while the 151 pounds pressure will send a one and one-quarter-inch stream 198 feet high; the one and one-half inch stream 222 feet high; the one and three-quarter-inch stream 241 feet high; and the two-inch 255 feet high—or the two-inch stream 205 feet higher than the 151 pounds can possibly force the five-eighth-inch stream. As these results of distances and pressures can all be proven in any lire department with proper tools, I will take up briefly but one or two more sizes—namely: The maximum height that a one and one-quarter-inch stream can be played in still air is 200 feet, under a pressure of 173 pounds, while the one and one-half-inch, under the same pressure, is sent 238 feet. The one and three quarter-inch, 257 feet; and the two inch, 275 feet—or an increase of 275 feet in height, simply by enlarging the size of stream. * * * “It is as a result of this rule (says Thomas Box’s “Practical Hydraulics”) that each particular size of jet attains its maximum height with a certain head or pressure, and that if the head is increased beyond that point, the height of the jet is not increased thereby, but is actually diminished. This result is anomalous: It may be that an excessive head breaks the issuing stream and causes it to meet with more resistance from the air than the jet of water issuing under a moderate head.” He further says:
“Experiments with excessive heads show an enormous loss; thus a one-inch jet in diameter, with 445 feet head, reached a height of about 109 feet only.”
Why the size of nozzle streams has not been increased is because till recently the nozzle could not be safely and quickly directed.
Even with hand engines, when good pressures are required, they are held with great difficulty—requiring in many cases three and four men to direct a nozzle. In handling nozzle pipes, the pull-back, or recoil is in exact proportion to thearea of the nozzledischarge and pressure applied. For an example, take for a basis a water pressure of 200 pounds, which can be easily produced on a steam fire engine. If the pressure is more or less, then the resistance or back pressure for the firemen to hold will be in proportion. On a basis of 200 pounds, it is found that the back pressure on a three-quarter-inch stream is eighty-eight pounds. A one-inch—it will be increased to 157 pounds; a one and one eighth-inch, to 194 pounds; a one and one-quarter inch, to 244 pounds; a one and one-half-inch to 352 pounds; a one and three-quarter-inch to 481 pounds; and a two inch to 628 pounds.
As to the weight which pipemen are obliged to hold with nozzle pipes, Mr. John R. Freeman, engineer of the Associated Factory Mutual Insurance company, shows that a pressure of forty pounds at the nozzle, with a one and one-eighth-inch stream, is about all that even a skilled hoseman can conveniently manage, without he has one or two more men to help him; and a nozzle pressure of sixty pounds will tax all the energies of three strong men to hold.
Hence, argues Mr. Robinson, modern fire duty should provide for the handliug of from 200 to 400 pounds of back pressure (which is in nowise related to hose pressures)—only about forty to sixty pounds being possibly available in the old way.
Two or more men, if well braced, can for a short time hold the pipe with a one and one-eighth-inch nozzle, wheu run at a high pressure, for the reason that the hose is kept straight to the ground, and the water helps to make a sort of strut, or support, which helps the firemen; but at a fire it does not prove practical, for the moment the nozzle direction is changed, this prop instantly leaves the pipemen. For this reason every engineer has strict orders, in case of fire, to gauge down his power to a safe limit for the pipemen. Many have supposed, erroneously, that the larger the size of discharge, the easier the direction of the stream, while the opposite proves true.
The accurate direction of streams up to two and one-half inches under any pressure can now be easily and safely accomplished, for (says Mr Robinson) the streams practically self-balance, and the direction can be instantly changed as desired. * * *
A boy eight years of age has directed at the same time four and one-eighth-inch streams—two in each hand—from two steam fire engines running at their highest capacity; also two one and three-quarterinch streams at the same time, running at their highest capacity.
Mr. Robinson claims that today over ninety-five per cent of the fire companies in the United States use the same sized nozzles and handle them practically in the same way as fifty years ago. But what answered for the old hand engines will not answer for the large steam and power pumps supplying thousands of gallons in place of only one as of old. With modern tools this increase in supply can almost Instantaneously be projected into a fire, if reaching large proportions, which will at once reduce the limits of heatand put the fire in control.
This large supply used to be forced through small nozzles under high pressure. But, as the power is increased on any size nozzle, the excess of water forces the stream into a spray flnerand finer, constantly expanding, and the stream reaching the distance, with the character of the the stream and its effect on the fire as I have described, contrary to every sound principle of hydraulics and the proper application of water on fire.
The branch-pipe system (Mr. Robinson holds) has become “worthless, except, perhaps, for small fires;” with it modern fire streams cannot be produced,and, though the water supply and the use of powerpumps is steadily increasing, the fire losses of the country are increasing in a still greater ratio—the conflagrations being those against which “no modern fire streams have ever been provided.” Municipal officers, therefore, should make every possible provision to avoid conflagrations; (1) by improving the fire service, as each improvement proportionately lesseus the fire risk; (2) by making liberal appropriations for the maintenance of the Are department. Mr. Robinson, in putting forward these suggestions,points out, (1) that property-owners who insure pay all the fire losses—a special tax on the community which equals —often exceeds—the municipal tax; and (2), as all ratesof interest are based on the risk of a conflagration, it this risk is not substantially covered, then the cost of insurance must increase from time to time to correspond with the growth of a community, to cover the increased risk of larger conflagration. * * * The fire service stands first in importance overall other municipal departments, yet it is found sadly neglected in too many communities and left for success too much to “luck and Divine Providence.”
Proper fire streams are essential, and, as their importance cannot be overestimated, whatever tends to supply that essential should be at once on hand — especially since seconds count at the beginning of a lire. Wherefore, Mr. Robinson rightly insists that no fire company should bo handicapped upon reaching the fire fora fire tool from the extinguisher stream to at least a two-inch stream. If but only a part of these different sizes can he afforded, it should be the sizes running from one to two inches in diameter, for the reason that the small fire can be conquered with the medium Hizes, while for a fire reaching into large proportions,the cannon stream is the only one that is effective. Some may say that the cannon stream may not he required for every tire company, but I think you will rind that a community large enough for a Are service is large enough to see some time the necessity of at least using the cannon sizes of fire streams; also the tolly, if but a certain quantity of water can he made available for the large fire, in dividing it all up into a large number of small streams.
Mr. Robinson observes that although the results itr sizes and distances of streams have long been familiar to all students in hydraulics, “yet little generally has been done for their proper application for for the Are service except the small fires ” He also states that the direct results and pressures with the different sizes of streams he has given are taken from standard works on hydraulics, and were obtained with a short nozzle about eight inches long, which was found best set as dose to the base of supply as possible; the results secured are without the use of lines of hose, so that the friction in lines of hose has not entered into the preceding results I have given.
Passing on to the application of these principles for practical fire service, Mr. Robinson asks if large and small streams can be produced in all ordinary fire departments. This question he answers affirmatively and adds that a new system has been devised which is adapted equally well to the largest and smallest cities and towns, and to all manufacturers having fire protection. It has revolutionized the fire service in producing and handling fire streams. Some may say that what looks well in theory does not always prove satisfactory in practice. I will say that constant experiments to perfect this system have been going on for several years—involving a vnst, amount of labor and thousands of dollars in expense in perfecting and adapting this system for all of the many duties required for the fire service.
This new system is a time-saver in the way of producing fire streams—an important factor in fire fighting. Mr. Robinson goes on:
As the nozzle used in the new system Is only about eight inches long, it admits of much quicker adjustment to the hose, and is much more easily carried than any former make of pipes. Any make of shutoff nozzles can he used as desired and not increase the nozzle length. To adjust it to the nozzle is a ques tion of hut one or two seconds of time, and for all small streams it is complete in about half the time of branch-pipes, so-called.
The tool to produce these large sizes of streams, in weight and space is about that of a three or fourgallon fire-extinguisher. It is made in sizes of two, three, and four-way sete. The time allowed for large streams, making all connections complete, with the stream in operation, lias been accomplished with the three-way. which is the medium size, in twenty six and one-half seconds, and has averaged in different fire companies about thirty seconds, under the following conditions—viz. : The device was taken from the wagon and connected with the hydrant, and all connections made complete—time taken on arrival of the company at the hydrant, and a full stream of water leaving the nozzle, with fireman directing the same. As the device above described can be set to work at once as soon as the first line has made connections, and the other lines connected as required without stopping the first stream,it gives even better time record lor connections in actual service.
An important feature in this new system, is, that it fully carries outfor the lire service the same general rule in hydraulics as I have previously shown—namely: It improves each size of stream, and as the size increases, the greater the distance, up to a certain size, and all sizes reaching long distances under very low pressures. I find the maximum of streams for distance and size in average fire departments is reached at about two inches in diameter. The minimum and maximum sizes in this new system run from three-quarters of an inch to two and one-half inches in diameter. What could be more desirable for a fire company, if the fire is increasing beyond the capacity of small streams, than tools at hand to send out streams in both greater volume and distance at a moment’s notice, without increase of pressure?
To show the practical workings of this system for the average fire company, I will cite a few improvements out of a large number that it has given in its more or less crude forms before reaching its present stage of completeness. In the past, from a hydrant having a gravity pressure of seventy five pounds, the maximum distance that a one-inch stream has been thrown is about 120 feet. From the same hydrant pressure a solid two-inch stream can now be thrown seventy-five to one-hundred feet greater distance. Increase thepressure to 100 pounds, and the two-inch solid stream reaches more than 300 feet. It has sent out in a public trfal test, from one hydrant, having a gravity pressure of only eighty pounds, threeoue and three-quarter inch solid streams all at the same time, 209 feet each; also from the same hydrant three two-inch streams, 179 feet. This decrease in distance with the three twoinch streams was because the maximum capacity of the hydrant had been reached with the three one and three-quarter-inch streams, although this was from an up-todate hydrant, and fed from a twenty-inch street main A fifty-pound hydrant will produce one and three-quarter and two-inch solid streams about 175 feet, and with each teu-pound increase in pressure adds largely to the distance; 135 pounds has sent a two-inch solid stream 450 feet; a hydrant pressure of 120 pounds has easily sent a two and one-quarter-iuch perpendicular solid stream 225 feet. Hundreds of records of similar tests in sizes of streams and distances can now be furnished from any section of the country.
The tools to accomplish the work tha It have described are pronounced by fire engineers as the most important, as well as the least expensive addition that can be made to a fire service. Singular to say, that as each of these many improvements has been brought out, they have been granted the first and only patents for devices toaccomplish thisimportant work.
Perhaps, some may say that actual proof in practical work is worth a thousand times more than any lecture on theories of fire streams. To such I might cite more than a score of cities this season, where it is claimed that this system has been the direct and only means at hand which has stopped a conflagration. Boston, since its complete adoption four years ago, has net up to this time bad a fire get outside the building in which it originated. Yet this fact does not prove that Boston is to have no more conflagrations; any city is liable to a conflagration, as soon as the size of the fire and its intensity get beyond the sizes of streams in use. As these improvements have been made they have covered as far as possible every detail of work, with a view not only to produce the best possible streams from given pressures, but provide for the safety and the convenience of the men in handling the streams. In this respect, perhaps, I should mention a single feature— namely:, the deadly electric current, that has grown to such an alarming extent in the past few years, is a comparatively new danger firemen are called upon to meet. A solid, stream of water striking a highly charged electric wire, produces one of the best conductors to carry its death-message to the pipemeu. This system is the only one that covers practically this important ground and meets the approval of the best electric expert, to insure safety from streams coming in contact with electric wires— a feature alone, if no other, that should insure its adoption.
In conclusion I will say: It will be seen that this subject covers a vast amount of interesting ground; a paper of this kind can touch upon only a very few of the most important points. I have endeavored, as nearly as I have been able, to show the principles of hydraulics as they should be applied in the improvement of streams in modern fire service. I have given the subject of fire streams and pressure a large amount of attention for many years, and have made thousands of tests with different sizes of nozzles, under all pressures in the scope of the fire service,and believe my deductions that I have here shown will prove to be practically correct. * * * [This paper] shows how superior streams may be produced almost instantly in any size. It shows that small streams should not receive high pressures to get the best effect, and that streams can be projected in both largely augmented volume and distance under low pressures. It shows how a large amount of wear and tear can be taken from the hose, fire pumps, etc., and their reliability and durability largely increased. It shows the only method to stop the enormous increase in fire losses and the only practical plan looking towards lower rates of insurance.