The open otot flow arrangement is shown hy the sectional model.
The eonica valve on the steam spindle is considered a better way for shuttini off the steam than allowing the spindle to fit in the apes of th steam cone, and might be appUed aiivantageously to every forn of injector, preventing the possibility of bursting the cones b IS. The iDJecturs shown in ligs, 3 onij increased delivery in gallons per hour of 35 to 40 jxir Giffard's original calcdBtiom. Thie U owing undoubt- tdlj to the improved proportions and the entin; Mcctuaion of the Utuoaphere attained by the use of the scli'-actiug ynWe.
TIte Principle of the Gijiird Injector. Of uiioree, necessary valves and coeka are employed.
The injector cannot work as hot water aa the pump, and the feed- ing must be very grtidnal, as the apertures of the pipes are very amaU. I am of the opinion that Mr. Hobbiaon himself doea not ahow a very clear perception d the thing. With your permission, I will endeavour to do so myself.
The operation of the Giffard Iiijifctor ia dependent on the kwi both of pneumatics and hydrodynamics, and its secret lies fact that uiider any given pressure aeriform bodies are propelled with a very much greater velocity than liquids. Thus, if would commimicate to water a velocity fer above anything that could be accomplished by hydraulic machinery, let us first Tort it into steiiui, then set it in motion and suddenly reconvert it into water by condensation ; the water will retain the velocity of the steam.
To illustrate by example. We have a steam boiler in opem tion, under 90 Iba. If we run a pipe iaoxa the k Iii' IB b. Perhaps under 90 lbs, ity of 1, ft. At an; rate I it for the purpose of tills illustration. Qow that the steampipe ia of just such lengtli and calibre as to contain, under 90 llw. Keraembpr it is moving 1, ft. It again, by means of outside machinery, we throw a jet of water of the same diameter with the orilice, ipd directed at it, with a velocity of 1 1 4 R. Bnt if the jet, by additional pressure, liii a velocity of ft,, then the equilibrium is destroyeil,!
II its velocity of 1, ft. How much more easily i mpidly will it [lenetrate, where even a velocity of ft. And suppose, now, that it Climes in contact with another cubic inch of water in a stiitu of rest. It will part with half its velocity to the latter, and liiitti commingled, will move on at the rate of ft.
Let ihese two come in contact with other two at rest, and again, the weight being doubled and the velocity halved, they will move ft. Still agtiin, let these four strike four -ithera in a state of rest, and we shaU. Of these eight, one is the cubic inch that 'n deneed out of the steam in the pipe, and here we behuld it commingling with and canying along seven others, by wbiob, i fact, it was condensed, with a velocity much greater than thi of a jet projected from below the water level of the boiler under the exiating hydraulic prssaure of 90 lbs.
In iact, however, there is a constant flow of steam, a euDstaiit condensation by an uninterrupted stream of water, and an unbroken jet into the boiler. It may be asked, if the steam jet itself were directed at b orifice ill the boiler would it penetrate i It would not It must be remembered that force is a product of weight and velo city, and here the weight of steam being so insignificant — it requiring 1, cubic inches under the pressure of o sphere to weigh as much as one cubic inch of water — the force would be insufficient to penetrata But it is a very different thing when water moves with so great a velocity.
The principle of the Gitfard Injector is applicable to othaf purposes than feeding boilers. It makes a good pump iix Rhalluw reservoirs. It would make a very powerful Are engint It could be used to drive light machinery, by tljrowing its jet into a turbine wheel running at a high speed. I have used it to propel a toy boat — not very satisfactorily, however — having a small copper boiler heated by a spirit lamp, and throwing its jet back under the stern. Nothing has been said, in this discussion, of the construotioD of the apparatus, nor was it necessary, as I presume that U fa miliar to all engineers.
I have aimed only to develop the priu' ciple. It is a very beautiful invention. Witeori's Doftltey Pump as exhlldttd at Hacre. Iron Works, Wandswortli ' Boad, London, exhibited several forms of donkey steam pumps fui supplying boilers and pumping water, Messrs. Wilson hxs introduced some improvements in the ariaugenient of tbea pumps, which are on Brown's patent. Wilson obviate this, and bmu other ftdvantBges hy their very simple — and valuable becaa eiinpio — arrangement.
To the pump-ram a stud is cast, projw ing at right angles from it, and working in a vertical guid The stud is brought sufficiently forward to admit of the low end of the connecting-rod to be jointed to it, in a line with ti crank-pin on the fly-wheel above, thus securing a direct line: We gii in fig. The pump-plunger E E continued upwards, and carries the piston F F; and at its ceul a stud G G, the parallelism of the plunger being kept by t vertical guide H H. The fly-wheel spindle or shaft L L ia can ' by two pedestals M M at the top of the framing. N ia the centric fixed outside clear of the frame, and is the sUdo valve for distributing the steam to the cylinder D by the po PP.
On Hie Generation of SIfatn. The crude idea first carried out in practice to place the lire under the boiler; and it evidently took its from the belief that heat possesses some inherent principli ascension, and therefore tends more forcibly to pass througl plates and enter water placed above a fiimoce than those locate! It is true that we cannot deprive the gases flowing from a furnace of their tendency to rise ; but it does not of neceaaity follow that heat- ing surface can be beet disposed in the top of a flue, or the bottom uf a boiler.
But it does not appear that in any large flue I! In tubnlar boilers the diameter of the Hues is unally very small, yet even in them heat is so slowly trans- mitted from one particle of gas to another that much heat escapes iiili, under better arrangements, need not escape. This pas- reluctance to yield up heat displayed by the gases finds no llel in the case of steam. If ateom did not give up he tbtm the products of combBstion do, the surface be an impoasihility. Seeing, then, that the reason why gas yields sinjply that it is a noo-conductor, the course of the ueer is clear.
This can only be cfiected by I the escaping stream of gas, and throwing it into eddies by obstacles placed in its way. In theory this by causing the flame and smoke to ascend through a with small horizontal tubes containing the water to Such boilers have been tried but have not answered the circulation of the water citnnotbe maintained proi very email horizontal tubes. This class of generator erally proved economical in fuel, but liable to rapid by use, and an inveterate primer.
Vertical water t Martin's boiler, answer far better, provided proper UK taken to free water circulatioa within tbem.
T7i skill is manifested by the designer, however, it is prevent the gases from rising towards the upper i water-tubes, which are usually filled with foam not lated to absorb heat. The only way to prevent this consist in contracting the araa of exit, so as to compel the to till all the depth of the flue or tube-box. It cannot be however, that this expedient is quite satisfactory, and it that a thoroughly good boiler irith vertical water-tubes transvf to the direction of the current has yet to be produced, are several such generators in use, however, which, although quite perfect, are more nearly so as steam generators than tire- tube boilers in existence.
I'lame bridges operate beuefictally for i reason. Galloway and held tubes act still more efficiently. With proper care tliis risk may generally be oToidel Probably better teaulta would be obtained in connection with such tubes by constructing the furnace in the shape of a brick oven at one end of the boiler, and leading the gases in the state of vivid cotnbuation into the flues than in any other way. The brick furnace would not coo! The aeheme has already been trkd with some success, we believe, and we know that it deaervea i.
Goventmetit Tests for Boiler Plates. After the puddling has been completed, the iron is removed 't in the furnace in.
Sometimes it is rolled in the form of narrow bars 3 in. The nairow-bars are cross- B pled with the wide bars, with the view to obtain a better re- B Hit upon testing. But great objections exist to this practice,. ENGINEEilING tACTl Tn many iustancea complaints have been made liy the 4 ' of boiler plates to the effect that the Governnieiit tests severe to insure good iron, by reijuii'iiig them to s which shall stand a tensile Btmin of twenty-two tons [ inch lengthways, and eighteen tons per equare inch era the plate; also a good hot and cold forge test.
In has been snid that the plates cannot be subjected to a strain without injury to the plate, with regard to tho i tests. It is, however, a well-known tact that iron plates fl made to stand the forged testa required by the Govemnt a tensile strain of twenty-six tons per square inch 1 and twenty-one tons per equare inch crosawaya of thi care and attention on the part of the makers. The tx by the Government with regard tn framing a code of t which plates of a certain thickness and quality must I bending both hot and cold, witL and across the g their being received at the dockyards, has been the i ing the attention of the makers to the reqairements of t ernment, whereby a better elaas of iron is now obtained i othenyiBe would have been.
But a very few yeara g only result the makers sought to obtain was a high tensilftiil The methods of testing iron plates for tensile strenj " very materially, according to the views of tlie different j employed. From experiments madu with circular and parallel-sided I pieces the difference was fiund to he very great.
The pieces of both shapes so prepared varied I I in diameter from 1 in. It will be apparent that when a parallel-sided I piece of iron of any length is tested, the chance of its breaking I at a point other than the centre, when the full strain is applied I I HHiiini iir even nnder tbe required tensile strain , is in proportion lii tbe length of piece tested, in consequence of the strain being tlie more likely to fall into a weak part of the plate, and also owing to the elongation of the plate. But when the piecea tested are tircnlar in form, the probability of their breaking at any other part than the emalleBt is done away with, aa the piece must break exactly at the smallest place to obtain the correct bnjaking itrain.
It will thus be eeen that, in testing iron, pieces of a cir- enlftr form have a decided advantage over pieces of similar length of n parallel-sided form. It is evident that this must bo tlie case, for pieces of circular form have a greater hody of iron behind the imdlest part of the cirde, which supports the piece while under Wry strain i and, further, pieces of circuhir form have a greater area of iron to support the weights when applied, and thereforo XK not so liable to elongation as parallel-sided pieces.
Some maDafacturers are of opinion that 1 in. The test pieces varied in width ftom one to eight inches. These experiments prove that tliere is a very great difference in the result with regard to the width of tbe jrieces tested. In some works, tbe testing of the shearings from the plates is considered a sufficient guarantee of tbe quality of the iron.
Wifl icon is put upon its merits for tensile strain, the pieces tO' operated upon should in no case he prepared hy punching tl from the plates, but hy planing. Boiler Explosiom of The report of Mr. Hiller, the engineer of the second above- aBmed company, ia well classified and arranged as to the natures it the accidents as tb.
In other words, one-half the accidents, each of which cost in round num- liers one human life and a ha! Marten reports forty-eight explosions with- lu the year, causing the death of seventy persons, and the griev- ooa injury of eighty-eight others. Of these forty-eight explosions on less than twenty-seven are attributable to malcoustruction fifteen , overprpssure five , or being worn out seven.
These totistics would be of very much greater value if it were practi- ctble, as no doubt it must he, to ascertain the total number of bmlers of all sorts in the area over which the report extends. I t Ny tlie eame sort of law, as to government regalatioiia inspection of boilers as of all other trades and inatTamenti tt endanger life and hcaHli, 'which has so long and so benefinU existed in Germany and Francfi. Here, however, we have steam boiler explosioiw alone reaching in two small districts of England, nearly killed per annum. Had we returns for the whole of the Sritish Islauds, we shall probably not be far wrong in assuming that from to persona are killed, and doable as many maimed, by boiler explosions every year.
I A few such eventg must always be etpected ; but to call such fsplosions of domestic kitchen-Gn! I We have no wish to say one nord against the existence and k of these boiler insurauce companies, unless it he so far as ir existence may tend to blind the vision of the public and m legislature to the real neceseities of the case. The leaaon of this is not far to seek; they are mere voluntary asso- ciations, devoid of the slightest power of control or of compul- sion beyond that almost nominal amount that is supposed to jprimg out of the mutual moneyed interests of the insurers and iif the insured.
These are extreme instance? At the vaij most, all that can he said for them is, ' This ought ye to havi done, but not have left the other undone. It is in both countries a real rojiirol, not a mere useless doing of the goose step of supervision oi inspec- tion, without any power beliind, as is the case with our railway inspection under the Board of Trade.
At the design and creation of the boiler, the engineer or boiler maker is not harassed by any vexatious interference with his arrangements or propor tions ; the State tells him that the science and experience of its engineering advisers have pointed out certain proportions as ad- visable: If any repairs, however trifling, he required to a boiler, a simpU form of notice must he addressed to the nearest communal in- m epector. In whatever in- rtacces these formalities are fulttlled, the manufacturer, or coal owner, or miner, has really no trouble, nor is a tlelay of an hnur needlessly given him, for there are plenty of inapectore at hand.
Hid thesQ are competent men. Bnt if the recklesa or impatient fflan should try to evade the law, he is very soon funnd out, and finds out his mistake to his cost. They had done so before, and equally cause- leaaly, and the inspector determined to read them a lesson. Adequate means are always at hand to find out what is going on oi this sort j and so the managers on the same Friday that the repair was completed — it only occupied about three hours — were itvlled by receiving a prohibition lo work the boilers until after ttioD again. They went personally to the inspector to cry: But is the case ;n: Each smallest district inBpector ia himself inspected, and has to report to ofiicer above him ; and, finally, the whole of the official gystem condenses its annual results aiid reports at head quarters, and goveminent haa before it at a glance the entire workings.
In effect, nothing can work better 01 more smoothly for all coacemed than does the system in Prussia, and we believe it does so nearly as well in France, though in the latter coantry the law is in some few respects a. At the present time, when the pub- lic mind is busy with the important— we admit, mai-e important — subject of education, primary and technical, it is not amiBS to urge the necessity of legislatively taking care of the bodies of the working class as well as of their minJa ; and now would fee a most suitable moment for a complete reconsideration and eon- solidation into an adequate and.
It would be now easy; in some year to coma, if these boiler insurance companies multiply, rested interests will arise in them, and petsonal opposition have to be encountered, and difficulties, which as yet scarcely exiat, will have to be met in Parliament. We do not think these companies are likely to extend very fast; they have not done so as yet, and the more they shall, the more their utter incapacity to deal with the evils will become apparent, 'During the past year,' says Mr. Hiller, 'four instances haTe occurred where explosion has been ascribed to deficiency oS water, and blame thn wn on the attendants who leere kUled.
Fletcher, would bo greatly to be desired in place of this. One sentence in Mr. Hiller'a report alone ia aufficieiit to show the entire inadequacy of the ' Toluntary system ' of these boiler companies, even in auch a close, dense region of steam, and amidst- so intelligent and Hvely a popnlation of manufacturers as that about Manchester ; — ' A large number of firma Lave not yet in- sured, nor placed their boilers under the inspection of any com- pany, chiefly, I believe, through a misapprehension of our advan- tages.
I beg to remind those owners that our inspection is not intended to anpersede their own care, or that of theii' servants, but to assist them in every way.
Where desired, we undertake the periodical inspection of boilers without insurance. I trust that all boiler owners will, by their voluntary action, procure such inspection of their boilers aa will render unnecessary that government interference which baa so often been recommended' Just so; 'the voluntary syatem ' here, as everywhere else, in education and the rest, proves a foilure. It is mighty good where, and so long as, 'the wishes are father to the wills,' of those who employ and applaud it. But let the former run counter, and the Yolunteeriug becomes a rope of sand. So it ia with the boiler owners.
It ia just those who most need inspection that dont wish to have it; just as tlie bricfcmaker who prefers the ahilling or two a week he gets out of his children of seven or eight years nld, compelled by liim to drag wet bricks when they ought to be at school, prefers the voluntaiy system, and deprecates any gov- ernment interference. But state supervision, and within just and miid limits, state compulsion, are jnst aa much wanted, and would be as wholesome in the one case as in the other.
Marten, the engineer of the Midland Boiler Association, we are enabled to give here the following portion of his report for the year , with illustrations. A small boiler to heat a bath. It exploded, causing great mage, because the connecting -pipes were frozen. All sucli joilera should have a proper sal'etv- valve.
Iriitit end over the fire. Main portion of abell was liriven I ji, and front end forward, and torn in its flight. Tube collapsed sideways from end to end, because it waa not strengtbeiied by hoops or other means, which were the more needed because it was slightly oval and the longitudinal seams were nearly in one lino. Boiler lov beatlog apparatus.
Fire was lighted without dc that, aa there was na safety-valve, all escape of steam we vented by the connecting-pip ea being frozen. Burst, and caused p dauinge, owing to the pipes being frozen. There wna no safetjh valve. Burst, atid did great damnge, because p rere frozen, preventing escape of steam. It liad w Kery lung time, and wns overheated and injured alnnf ftvctured line.
Flat ead blew ont, throwing boiler iipirards by reaction, but shell and tubes were not injured. Thu flat end was not sufficiently stayed, having only one stay-rod to Llie centre, the bolt of wfhich was broken. Fire had been out some days, and the boiler barat soon after rekindling it, and did much damage, because the Bnpply-pipes were stopped by froat, and there was no safety-valve far escape of ateam.
Kitchen boiler, which hurst because the snpply-pijiea were stopped by friwt, and there was no safety-valve. Small boiler to 6 horse power engine. Gave way at centre of furnace, and water forced oat at hotli ends, and it was suspected that the water was low. Tube, 3 ft,, unstayed. It was said to be short of wi but most likely the true cause was the weakness of the tube. The cause of explosiou was ovep-pie sure from the safety-valve being screwed down. Fire-box and tubes blew 00 llie cause if exploBiciU was overpressure, as the safety.
Front end kttacbed bjr "lislit angle-Iron, which gave waj, leaving the Bbell iroiiioiTed. The platea were rednced I" 'i knife edge in line of fracture. Furnoce-tubo biled, and cullapaed from nne end to the other, except about i ft. Plain cylinder, 3 ft. Piece of top ripped out from manhole, and allowed K lid to blow out tbrough miuiLole. The canse uf the explosi was the large manhole and over-pressure. The Baffitj-vaive B too small, and very roughly made. Barrel blown away and b to pieces, leaving fire and enoke boxes.
ITieends a I' collapsed for its full length, every joint being broken. Two plates lately put a Iwttoii gave way, Htiil shell rent alitng licttom aud upenwi tH dividing into several pieces, which were scattered to great diat lint are ari'anged in ftketch ao as to show their original positidi The cause of explosion was toy frequent repair over the fireplm ' anil external tiriiig, Ko, Bottom blew ind Wtts toru in pieceis. MaLn portion of shell fell over oo to Mher Iwiler. The osase of explosion was ileep corrosion along Ib bottom where it rested on tbe brickwork.
Rtnt along bottom, allowing central ig of plates to open out The whole boiler was thrown aome tance by the reaction of issuing contenta. Tbe cause of ex- n was coiTosion at midfeather wall, the plates being little ir than paper. TI Two-tube Cornish 31 ft. The cauee of explosion was overheating, becaua the water was being let low before all the lire was out.
Siiie-plate in the upper part of high top fire- box blew away. The cause of explosion was most likely the boiler being made the frame of the engine without allowance for expansion. Small piece of plate was blown out near the bottom, and the boiler was displaced by the rpaution oi issuing contents. The cause of explosion was extensive extemi ' corrosion on the lower part. Eent along the acams, whiel: The cause of explosion was defective form ani it state of shell.
I I plate blew out while being canlbeil at a jump-joint in back Tiia cause of explosion was bad construction and ', X of stays, and also want of proper core in working. The force of eiplosioD caused tht neighbouring boilers e unseated. No details have been obtained as to the cause BXplosioi.. One-lube Comish, 11 ft. Gave way under- I Death. Front part and tnbe thrown H I the fronL The cause of the esplosion was extensive c the bcittoni where it touched the walls.
The causa of tbe explosion was c m locked aafety-valve and defective const rue tion. Plain cylinder, 1 2 ft. Main portion thrown back, and front forward. Front torn all roniid the root of angle- iron, and atay-ri? Tbe cause of explo-. Parted at third aeftra,aiidiiont thrown Breeahes tube, 25 fl. Main shsl not injured Batk part nf tube remained in boiler. The cause of explosion was the want of p per stays or strengthening tubes, and consequent weiilcQf There was only one safety-valve of small size.
Rain cylinder, 25 ft. Had been a one-tubs Corniab, but tube haii n taken out, leaviug fiat enda. Buck eucl waa blomi uut.
Tube collapsud for the iLile length, but no pai'ticulars of the cause obtained. One-tube Cornish, 18 ft, long. Uiameter; tube 3 ft. The cause of exploaion waa extensive corroeion on lb part resting on the midt'eather wall No. Ligh ; platoa g Bottom domed up 3 ft. The cause of explosion was undue pres- ; for an old Iwiler of such weak shape. Two-tube Gomish, 22 ft. Rent along bottoiu, and abell blown away, leaving tubes and ends nearly uniiijaied.
These were not typos, the first is in the Chapter-2 exercises. Tlie shell plates are f in. II its velocity of 1, ft. Mount Hood is at once the most recognizable icon in Oregon and yet it is little known by the multitudes that live in its shadow. This economy was soon, noticed by observant engi- neers, and the value of superheating of steam was pretty uni- versally acknowledged But, as we have already said, that there are those who, because all the phenomena attendant upon its use are not easily, or at all, explainable, come to the decision that there is no practical advautage obtained by its use. These are placed together so that they form a series of five vertical conical tubes, connected by transverse tubes at the bottom and nea?
Ihe w of exploBion was that the bottom was corroded to a knife edge all along the midfeather wall Ko, ii. Plain cylinder, 30 ft.
Bent over fire neat wbero a new plate 1 lately bven put in. Front part of shell opened out and tent,! The cast-iron mouth-piece of m bole fractured from insufficient strength, and allowed lid a upper fiango to blow off. Coroners' Ingueeis and Boiler Explosions: Sometimei i mwiy as ten and even twenty lives have been sacrificed single exploflion. In the earlier years of tb Association's operations such complete records were not kept all the explosions occurring throughout the United Kingdom has been the case more recently; added to which there can 1 little question that some have always escaped its vigilance, so the whole number occurring fi'om year to year has never bee fully reported.
The list just given, however, of the lives ficed is a sufficiently serious one to excite attention, while it mfi be stated, in. Many exploaiona arise frcim the use of old wom-out boiltrs, whicli have been ailowed to be bo eaten away either by external or internal corrosioa that the platea have Iwcome reduced to the tliickness of b.
Others arise from collapae of the furnace. Others, again, are due to weak manholes or de-: In many cases, too numerous to lefar to in detail on the present occasion, witnesses are adduced to prove tliat the exploded boiler which has just bteu rent in fragments was a thoroughly sound one, indeed the best of the series, and perfectly safe at the pressure at which it was worked, or at uiie twice or three times as high, so that the explosion was per- ii.
On one occasion a witness attributed the ex- ,. Many other aiml caaaa might be given, but these will auffice to show the cbaoq of evidence too frequently given at coroners' inquests as to I cauBB of boiler explosions. With such investigations it must be clear no progress caoj made, and fatal boiler explosions recur with sad couetancy.
I There are, however, a few, though very few, exceptions toi rule i one of which occurred in the city in which this meetira the Association fur the Advancement of Science is now hi The explosion in question happened about two years ais killing seven persona, and laying the premises in which it curred in ruins. The causa of this sad disaster was simply thatj boiler was a bad one though new, and made under special cf tract. A few such verdicts would shortly j the country of boiler explosions, and it is in behalf of ai jilain and outspoken verdicts that this paper is written. The frequency and fatality of steam boiler explosions baa fre- i-iitly been used as a plea for a Government syatera of compul- iury inapection, and juries have frequently coupled with their Tardicts a recommendation to this etfect.
There are, however, serious objections to this course. Such a system of inspection must necessarily be carried on by rule, and however wisely such a code of rules might be framed, and however liberally carried out, it would be impoaaible to prevent its proving a harass to the individual steam-user, and au impediment to progresa ; so that it should only be adopted as a la.
It is fimty be- lieved that faithful inveetigationa and plain speaking would do much to put down exploeions in the course of a single year, a therefore the plan suggested for rendering coroners' inqueats w regard to boiler explosions of greater efficiency, is commended to the consideration of thia aection of Che British Association for Ha Advancement of Science, heliaving-that it would prove a practicil step towards the prevention of the present loss of life through tlw constant recurrence of steam-boiler explosions, and render a aji- tern of compulsory Government inspection unnecessary.
Boiler Exptosiotig at Ironworks. Dawes, was conoludod on the 22 1 iiistanl with a verdict of ' AccideDtal Death. It bad one down-flue ind two cross-flues, was supplied with two 5-in. The plates were ths ga and the boiler, which had been in use some years, appeared t in good condition.
It was generally worked with water about 18 in. At that time, as indi' cated by the float, it was full of water. The pump was, at t same time, working in good order. Another witness, who w injured, spoke to there having been a rush of steam, by which h was scalded, three minutes before the explosion. Tbe scientific witneea examined at the inquest wha Mr. E, of the Brinsworth Ironworks, Rotherham. The Best Books of Check out the top books of the year on our page Best Books of Product details Format Paperback pages Dimensions Looking for beautiful books?
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