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I.\;DUSTRIAL AND ENGINEERING CHEMISTRY CONCLUSIONS
The liquefied petroleum gases, owing to their inherent properties, have many characteristics that make them especially adapted for fuel purposes. The fact that they can be transported and stored in the liquid form renders their distribution extremely mobile and flexible. The high thermal content provides far greater thermal capacity in storage than ncncondensable gases, butane having, on a thermal basis, a storage capacity 136 times as great as natural gas a t 5 atmospheres. The absence of sulfur and other impurities obviates the necessity of purification. The fact that they can be readily transformed from the liquid to the gaseous state results in high efficienciesand low-conversion cost. Uniformity of product insures constant gravity and thermal value with attendant ease of control. These advantages, viewed from both economical and technical aspects, and the fact that these gases are available in
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large quantities, with vast potential reserves as yet untouched, assure the liquefied petroleum gases an important and secure position among commercial fuels in the future. The utilization of these products is a means of conserving valuable natural resources. The problem is one of creating a demand which will provide new outlets. The solution lies in the cooperative efforts of the producer supplying the product, the engineer in scientifically solving technical problems, the manufacturer in furnishing equipment, and capital in furnishing the necessary finances. Butane-air plants, because of their low plant investment with consequent reduction in fixed charges, their low fuel, labor and operating costs, and their ease of operation, offer one outlet for the liquefied petroleum gases. I n addition, this process furnishes modern gas service to an increasing number of people a t a fair cost and, a t the same time, yields to the gas industry a fair return on the capital investment.
Eliminating Noise in the Chemical Industry’ W. F. Schaphorst 45 ACADEMY STREET, NEWARK, N. J.
Sound and vibration are closely related. Since noise a t one unpartitioned end of URING recent years in the chemical industry is usually nothing more or there has been R rapid the building. They estimate trend t o w a r d noiseless than “loud sound,” it is plain that, to muffle noise, t h a t e f f i c i e n c y will be inlessness in industry. In fact a damper need only be Put on vibrations- Examples of creased 33 per cent. ways of eliminating vibration, such as wall board, isolaI n 1930 the Department of noiselessness is being sought tion of machinery, and mufflersfor Pipe noise are given. Labor of the State of New almost e v e r y w h e r m n the Problems in connection with gears, the joining of a York issued a b u l l e t i n ( I ) streets, in the home, in office metal and metal, electric motors, and miscellaneous which deals with investigabuildings, and in factories, noise are discussed. tions and reports on noises in ’ Noisy m a c h i n e s that were factories as related to hearing satisfactory a few years ago are unsatisfactory now. Noise makes for inefficiency. Noise and cause of deafness. Only one paragraph from the bulletin, reduces production. Noise has often been the indirect cause a recommendation which is headed, “Certain types of machines of accidents. I n fact illness is sometimes attributed to noise. should be isolated,’’ is reproduced here: “Since it was found There is no question but that it causes deafness. that some machines, of which there were only a few in a room, determined the degree of noise for the whole room, the amount Quietness Increases Efficiency of noise and any consequent fatigue or permanent effect on Special tests have been made by an expert typist who can hearing could be reduced for workers on quieter machines type 150 words a minute. The tests covered a period of two who are subjected to the greater noise of the machines of weeks. I n one series of tests normal noise conditions were other workers.” Enthusiastic advocates of quietness in the factory claim permitted and in the other series noises were eliminated. The typist herself used a noiseless machine. Results proved that the present cost of unnecessary noise is greater than the that under quiet conditions she could do 8.2 per cent more nation’s fire losses. They claim that all unnecessary noise work per day than under noisy conditions. The same tests will eventually be unlawful. It is well known that noisy factories are often the cause of depreciation in surrounding were applied to a man, and the results were the same. Consider the telephone, for example. Every chemist is real-estate values. On the other hand, some manufacturers do not seriously familiar with the many efforts that have been made to render telephone conversations audible. There are devices to clamp concern themselves about noise and quietness. They seem over the ear which assist in cutting out noises. Telephone to think that noise is a necessary evil or not worth eliminating. booths are often installed in factories and offices solely be- Some of them play safe and locate in rural communities or cause of noisy conditions. Obviousry, quietness is to be pre- small towns where there are no ordinances against noise. But the modern tendency in the better factories, regardless ferred. The first windowless factory building is being erected by of size, location, and laws, is to reduce noise as much as practhe Simonds Saw and Steel Co.; this remarkable factory will ticable. embrace everything that is new, including noise reduction. Noises and vibrations which are a nuisance are already unIt will have acoustical ceilings, walls, and floors, as well as lawful, For instance, a concern in New Jersey manufacturing cork isolating mats, and every device for general dampening chemical devices and conducting an experimental laboratory of noises in the manufacturing processes. It is quite possible in which delicately adjusted instruments were used, brought that this radical departure from standardized construction action against a neighboring plant in which a high-speed enwill revolutionize industry. The builders contend that noises gine was operated. The vibrations of the engine caused will be so subdued that the plant office can and will be located trouble in the plaintiff’s plant. The defendant maintained that the plaintiff should not attempt to carry on his business a Received July 21, 1931.
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in that location if he did not like the vibrations. He stated that it was a factory district in which vibrations and noise were permissible. Tlre plaintiff won the decision. The defendant appaled to a liiglicr court but that court also decided in the favor of the plaintiff. The following, in part, is what the higher court said ahout it: The law guards jealously, for a11 aiike, t h e cnjoyment of all private propaty. The right of enjoyment is surrendered in a factory district only to the extent of the incoiiveniencc incident to the character of the business carried on there, no more. The ceaseless pounding of the vibrations from the defendant’s ciigine against thc walls of the piaintiii‘s mill is not incident to the neighborhood. The same annoyance would happen. under the same conditions, if both factories were on a farm. It was not a neighborhood hezard to he anticipated, and is not one to be suflcred. Community vibrations must be endured, but vibrat ing a community is a nuisance.
Fieure I~-Nafural-CorkIsulation M a t Cwk strips :>IC Ireid twether by riirrouncline sieei IPime.
Some uuisy tnac1iiiit:s itr,, iiiiecoiwiiiiciil as \veil as offeusive to the sense of licering of everybody concerned. This writer Itas freqriently seen foremen of noisy shops heckon a man into a private room or ot,her quiet place so that both could converse more readily. 1)ariiig tlie conversation tlre workman’s machine is idlc. 1)chitc: distinct instruction is essential to efiicimt inanagcment. It is not had practice to ea11 a man away from his work Sor a few moments, where noise is unavoidable. Uiit wlicre tlie noise is preventable, it sliould be prevented. The worlman can then continue his work while conversing with the foreman, and time is not lost in running in and out. Not only is good felloudiip enhanced, production increased, and quality improved in this manner, but the efficiency of tlw niacliine that has been quicted is generally improved. Simply bpcaiise noise has been associated with work in years past is no reason why it should continue to be allowed. Expcrierm, logic, and economy all tell that noiselessness is an ideal state which sliouid be attained as nearly as possible. There are very few noisy machines that cannot be quieted and niade inure efficient. What Is Noise?
Noise may be (ictined as a,ny disagrecable souiiii. Of cuurse it is not always possible to distinguish positircly lietween noise and noiselessness. A iriacliirie which is not noisy but which can novertlieless be licard may be called eit,licr noiseless or quiet. ‘Yo some people a given souiid iilay b e iigreeable and to others tlie same sound may he disngreeaide. Thus j w z is music to some Intt noise to others. The words ”noiseless” and “silent” shorrld not be uscd interchangeably. They are not synoiiyms. An instance of the iriisuse of these words is au article which appeared in a prominent power-plant publication entitled, “Silencing Compressm Mtiffler.” The mthor of t h e article explains in detaii xhat he did to the muffler and then ends the article with this sentence: “Wlien t,iio engine was again started the noise was reduced to a minimum.” I n otlier vords the muffler, wliich was snpposed to he “qiiiet,” was “silenced.” Yet after it was “silenced” tlic “iioisc” wlab reduced to a minimum.
Citing another histance, this writer does not approve of the name “silent chain” and lias never yet seen a c h i n that was truly silent unless it was enclosed in a sound-proof case or sizbrrierged in lubricant. Manufacturers themselves admit that silent chains are not silent. For instance, a certain advertisement states in bold letters at the top: “That steady, even hum tells you the story of the efficiency of our chain.” The hum of a “silent elisin” is beyond comprehension. Yet i t is quite aertain that tlre manufacturer of these chains is sincere and honest. .411 manufacturers of chains of that type call them “silent.” More suitable words would be “noiseless” or “quiet.” When iiew these chains may be quiet, hut with age they become less so. I n fact the author has heard “noisy” so-called silent clutins. A properly designed slipless belt drive is usually a close ~ p proach to a truly silent drive. But even a slipless belt niay make a swishing sound, the volume of tlie sound depending upon tlie velocity of the belt. Owing to the quietness of belt drives, there have been cases where tlic “silent chains” were removed and replaced by belt drives becanse, as the owner said, “The silent chains are too noisy.” In legal actions complainants have gotie to the extreme uf using a stetlioscope for detecting noise. That, i t seems, is going a hit too far. IS sound cannot he detected without a stethoscope, it certainly should not be called “noise.” Science has proven that sound and vibration are very closely relabed. If there is no vibration there can he 1x0 sound. Vitrrat,ion is the cnu Sound is the effect. To eliminate s r ~ n i dis mcwly to eliminate vibration. Since noise
Figure 2 -Dleeel-EnCine Fousdafion Isdated on All Sider n n d on Base wifh Cork
in the clieirlical industry is usually nothing more or less tlmii “loud soimd,” it is plain, then, that to milffle noise a damper need only be put on the vibrations. All of which seems like simple theory, but the practical side is not always simple. There is the exaniple of almost, any hammering process. Iiard metal against hard metal is invariably noisy. Metal against wood is less noisy. Metal against soft putty is quiet. Feathers against feathers are almost silent. Feathers against feathers, however, is not a problem in tlie chemical industry. The difficult problem confronting the chemical industry is to eliminate the noise caused by striking hard substances against hard substalms. Steel rivets cannot he clinched with a barmner made of lead. A steel hammer is required. That is why the hammer-riveting process is so noisy. Valuable Noise
There is sucli a tliing as a valuable noisL-a noise wlicii warns of danger, snch as t.he automobile horn, the locomotive
whistle, tlie bell on tlie fire cnginc, ctc. Such noises are necessary. The exhaust noise of a safety valve, of a gasoline engine, an automobile, etc., however, is of no d u e and there. fore should not be permitted. There are necessary unpreventable noises and noises that warn of danger nhich are certainly ,111 right. Bnt unnecessary, deafening, sickening noises are wrong.
Air noises are generally more difficult to muffle,such as the noise of a riveting lranimer, of a pile driver, or of open gears. AIR NomE&ince the eliminatiom of noise is dependent upon the stopping of vibrations, i t is obvious that any medium in the air which has a different density and elasticity, and therefore a dserent vibration rate, is likely to stop the noise. IIence one method whereby air noises may be effectively rnufled is to completely enclose the offending noise source. Sometimes an entire machine must be enclosed with thick sound-proof walls and doors. Tests indicate that a large room eliminates noise more effectively than a m a l l room. Electric motors are sometimes boxed in. When enclosing motors, provision must be made for ventilation so that the rotor will not become too hot. Chains, gears, etc., are commonly hosed. STWLTUI~AL Nors~s-'l'o eliminate structural noises, many substances are interposed, such as cork, rubber, felt, or almost anything with a different vibration rate. Some of the combinations of materials and designs are patented. Noise-Absorbing Wali Board
Flailre 3
-Blewer and
Motor
Unit on Noireless
Foundation
Blower is reparated from duct by
w ~ V I Sseetion.
During recent years the chemical industry has done some excellent work in coiiperation with pulp and paper, sugareane, and otlier industries in perfect.ing tlie so-called patented wall hoards now on the market. In general these patented boards sewe three purposes: (1) They stop air noises very well. Air noises are impeded because these wall boards contain a multitude of tiny air cells and are made of a material that does not readily conduct sound. In other words, they have a vibration rate that is quite different from the air vibration rate. ( 2 ) Heat and cold camnot get through easily. (3) They are easily applied, being made in large comparatively thin sheets which are easily cut, fitted, and nailed in position.
Regarding necessary noises, there are such things, too, as efficient noises and inefficient noises. It is well known that steam whistles are noisy, but it is not so generally known that such whistles are very inefficient. The United States Naval Proving Grounds, Dahlgren, Va., reports that a 12-inch whistle may consume as much as 400 horsepower. The investigation was carried on by theGovernment insearch foreffective and efficient fog signals. The siren is much more efficient. When necessary noise is made, i t should be produced eeouomically. Noise-Measuring Instruments There is no true standard of noise. It is a relative tern]. For that reason an instrument has been dewloped which is called a "sound analyzer" and which actually meaaures noise. By means of this device, which is electrical, any machine can be given a noise number. It takes a measure of the amplitude of the sound vibrations. It enables the pmchaser, when buying any given machine, to definitely specify the quietness of that machine. There are also other devices on tlie market which are useful for analyzing vibration problems. The fundamental principle of one of these devices is similar to that of the seismograph. The vibrations are recorded on paper, making it possible t u prove conclusively whether or not vibrations have been eliminated after alterations have been effected. Another device utilizes a combination of the stroboscopic and seismograph principlesliglit flashes and vibrations. Merely touching the instrument against the machine instantly gives a diagnosis of the machine's vibrations. Two Ways of Transmitting Noise Noises arc transmitted in two ways: through t,lie foundation and through the struetiire, and directly tlirougli the air.
Fiavre 4--Motor and Blower on Separate Foundafluna of Wood and Cork Cork mat is held together by steel band.
Patented wall hoard is being wed in ever-increasing quantities for enclosing noisy machines. I t is being used for enclosing offices and other rooms where noiselessness is essential. Existing rooms as well as new ones can be quieted by the use of this modern board. It may simply be tacked onto the inside or on the outvide of the present wall. This modern type of wall board is light in weight, inexpensive, durable, and ideal in almost every way for noise elimination and appearance. For example, it holds plaster; that is, tlic plaster is placed directly on it, requiring no arlditional binder. Often, instead of being plastered, the board is painted or othemise decorated.
1199 Machinery Isolation
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T I E iiitrrjiusing
