NOZZLES AND PLAY-PIPES.
在《华尔街日报》最近的社论pointing out the facts that the streams of water obtained from our Fire Engines are not in proportion to the power exercised by the Engines, nor to the capacity of the hose, seem to have attracted marked attention. The articles have been widely copied in the scientific and specialty papers, and we do not doubt but a train of thought has been aroused that will set our practical Yankees at work to remedy the difficulty. We intimated that, in our judgment, neither the play-pipes nor nozzles in general use were ot a character calculated to secure the best results, and we asked “ who will invent the nozzle of the future?” In response to this inquiry, Andrew J. Morse, of Boston, has written us a letter, not tor publication, containing some hints upon this subject which we shall incorporate in this article. Mr. Morse is a veteran worker in connection with Fire Department suppl es, an inventor of many valuable appliances, and a scientific and conscientious workman in whatever he undertakes to do. He has devised one of the best couplings made, has made various improvements in nozzles and play-pipes, and his latest invention, the “ monitor nozzle,” attracted much attention and received unqualified approbation at its recent exhibition at the Chiefs’ Convention in Boston. A full description of it will be found on page 297 of the current volume of THE JOURNAL. We regret that Mr. Morse did not put his ideas in form for publication.
我们已经注意到，在离开喷嘴后很快就会出现水喷水，并且几乎无价值，而不是被投射为固体水体。我们的 - 蒸锅能够提供足够的水压2J4英寸的软管提供自由的水；游戏管和喷嘴是根据所谓的科学原则建造的；然而，在喷嘴上传递的流与为其投射的功率不成比例。软管中摩擦的电力损失大大损失，但这并不能说明传递的流不足。最终，软管连接了一个锥形的游戏管，并将其逐渐变细的喷嘴，从而将直径2 1/2英寸的水迫使喷嘴通常1 1/8或1 1/4英寸。直径。现在，我们的决定是，对于不足的流提供了不足的流，游戏管和喷嘴的故障构造在很大程度上是负责的。我们知道，科学工程师已经制定了支配游戏管和喷嘴构建的规则，但是，考虑到这种构造方法并没有给出令人满意的结果，这对某些不科学而是彻底的，这不是很好实用的人，试验与规定的方法完全不同的方法？ Take, in fact, a new departure in the plan of delivering water upon a fire, and see if something better cannot be obtained. The tendency of a stream to spray so soon after leaving the nozzle is owing to a lack of harmony of proportion between the outlet and the supply. This can be demonstrated by using a spray nozzle, which, by closing, diminishes the outlet, thereby increasing the velocity of the stream, and causing it to spray; open the nozzle, thus restoring the outlet to its full capacity, the velocity is decreased, and the stream becomes solid. This is the effect produced by a spray nozzle, and, under the usual conditions of use, all nozzles are, to a certain extent, transformed into spray nozzles. To illustrate this, let us suppose a Steamer at work and forcing a stream as far as it is possible for it to do and retain its solidity ; the distance thrown not being sufficient for the work required, it is usual to call for additional pressure at the Steamer. Additional pressure is put on, more water is forced through the pumps and hose up to the outlet, which not being susceptible of enlargement to accomodate the increased volume of water, an obstruction is presented to the flow of the water, and the nozzle becomes, to a certain extent, a spray nozzle, tearing the stream to pieces, and delivering it in the form of spray. The extent of this spraying is proportionate to the increase of pressure beyond a point that is in harmony with the size of the outlet. A good illustration of the effects of pressure above the capacity of the outlet is to be found in the ordinary soda water fountain. These are ordinarily charged to a pressure of 180 or 200 pounds. When the draft tube is first connected, the stream is forced through the outlet with great violence, causing it to spray into fine particles; repeated drafts reduces the pressure in the tank, causing the water to spray less and less at the outlet, until finally it is delivered in a solid stream, the amount of pressure having been exhausted until it harmonizes with the capacity of the outlet. The condition of the atmosphere has a considerable influence in causing a stream to spray. When the atmosphere is humid, and full of moisture, the water as delivered at the nozzle has a great affinity for the surrounding moisture in the air, and the particles constituting the outer surface of the stream have a tendency to separate from it and mix with those particles with which the air is charged.
Two remedies to overcome this tendency of streams of water to spray, suggest themselves. One is a nozzle so constructed that it can expand or contract to correspond with the pressure applied to the stream passing through it. The second is, Engines of greater capacity, so that a large outlet may be obtained in harmony with the pressure exerted. It is a question in applied mechanics whether an expansion nozzle can be constructed that will work satisfactorily. We believe it can be. and that it will not be many years before nozzles will be used having an inner diameter, say, of 1 1/8 inches, capable of expanding under pressure to two inches. While this would, probably, give a satisfactory nozzle, there yet remains the objectionable play-pipe, with its tapering sides for the water to impinge upon, creating friction, and churning the water as it dashes from side to side into a foam. The introduction of a core into the play-pipe to straighten the stream has been found to be an advantage, but it merely lessens the evil without overcoming it. What is needed is a radical reform in the method of delivering the stream when it has been forced to the end of the hose.
In ,this connection we desire to call the attention of officers of lire Departments to the importance of ascertaining the maximum of service they can obtain from their Engines under certain conditions. They should see how much pressure will throw a solid stream the greatest distance through 500 feet of hose with the play-pipes and nozzles they have ; then add 500 feet more hose, and see how much additional pressure the Steamer must carry to obtain similar results. It is important for every Engineer to know just how to obtain the best results under given conditions, and the length of the line of hose, and the diameter of the nozzle are matters that have a direct bearing upon the manner in which the Steamer is to be worked. We shall be glad to receive suggestions upon these important points, and reports of tests made in the way of solving the numerous problems presented in the Fire Service.
