MANAGEMENT OF THE OVER-TYPE BOILER.
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A Useful Set of Rules, the Observance of Which Will Minimize Trouble and Avoid Injury to the Boiler Tubes.
By Chief Engineer.
AMONGST OTHER things, it has been, for some , .timeipast, part. of ins business to attend to complaints,. from -steam wagon (over-type)
owners, and the most frequent troubles I have .had to deal with have been in connection with the boiler. ' These being of the locomotive type, require a certain amount of care; if they are to work with :satisfaction
to the owner. , . The attention demanded is only that dictated by common sense, but:if the boiler is in the hands pf a careless or ignorant man this attention is olten sadly ,wanting. I, therefore, propose to give, a few hints which, if followed, will -be found greatly to dithinish• the various small troubles that are liable to occur..
from time to time. ' • .
The most frequent difficulty is that of leaking tubes,. but, with proper management, this need not' beeIt a tube is found to be leaking, it should be expanded at the very first opportunity, and not be allowed to remain in this condition for any length of time before receiving attention. If this happens it will be-found. that, usually, no 'amount of expanding will stop the leakage, because, either grooving of the tube and 'tube plate will have taken place, or a deposit of impurities from the water will have lodged on the -stir-face Of th4',.tube whewe it passes through the tube plate, making it impossible again to-form a, proper steam-tight joint.
When this has happened, the only thing to do is to withdraw the defective tube, anneal and clean the ends and clean the holes in the tube plate. After this is done, the tube may be replaced and expandedf again in the usual way. .
Now, the Cause of leaking tubes is, in nine eases out of ten, due to ignorance, on the part of the drivers, of the proper method of attending to the fire. If they would bear theafollowingrules in mind their troubles would' largely disappear :— L Place 'a small amount of coal on the fire ' at frequent intervals. .
2. See that the bed of fuel is level,' or, if anything, rather higher at the sides, espeeially against the tube plate. This prevents cold air rushing up the surface of the tube plate and impinging on the tube ends.
3. Be •careful that the bed of fuel does not burn into holes. If this occurs, cold air willl`pass through the uncovered part of the grate and cause leakage.
4. Do not keep the furnace door'open lengerthan is absolutely necessabry.
5. If possible, arrange the stoking to avoid adding fuel while, the wagon is pulling heavily uphill, beeauSe, if the furnace door is opened under these eonditions, large volumes of cold air arerdrawn into the furnace, due to the high draught caused by the heavy exhaust of the engine in the funnel, and this cold air causes leakage.
6. Especially 'when using coal for fuel, it will often. be necessary to admit a certain amount of air over the fire, through the fire door, in addition to the air that enters through the ashpan door. This is also especially the case immediately after a fresh supply of fuel has been added to the fire, which must he done judiciously, so that an 'excess of alir is not adnaitted to chill the firebox tube plate and start leakage.
7. •Do not be tempted to use the firing tools too frequently. Fuel, judiciously introduced and carefully spread, will entail a minimum of poking and interference with the bed of fuel and will indirectly save coal.
c38 ...8. The fuel should be broken to the size of a large walnut. • • •.
9. Constant attention should be paid to the water level in the boiler, to pi:e'vent it getting so low as to cause overheating to the firebox. The water supply should be regulated so that the pump is constantly feeding, the amount being-regulated to suit the de
mand for steam. this •means, the best. evaporative results will be obtained and undue straining of
the boiler avoided: .
10. The boiler :shOuld be properly washed out after every•100;houra working., , This should be the limiting period under any conditions and, if. bad water hasbeen iinaVoidably used -toany•great extent, the washing mit should etake. place more frequeetly.. When washing out, :care shotild be taken to ascertain that no depositeremains' onthe tube plate and amongst t,lie tubes adjacent. It as here that scale will begin Le aceumulate most rapidly and, if it is allowed to harden amongst the tubes andagainst the tube plate, the latter' willget overheated, tube leakage will commence -and, possibly, the tube plate will become fractured.
Ferrules are sometimes used to prevent ,tubes leaking, but the writer has always found that, -unless these are applied when the boiler is new, they are not very effective, because the expanding Of the tube which takes place when the ferrule is 'inserted is powerless to stop the leaking if: it has already been allowed to continue for any length of time, for the same reason that the use .of the expander is ineffective in most cases if continued leakage occurs as mentioned above. An exceedingly useful-type of boiler tube ferrule is that known as the "Barron ". ferrule, a patented device. The ferrule is in two parts, an inner and an outer element, and is so arranged that, when it is forced into place, the tube is expanded by it in the tube plate, equally throughout the thickness • of the plate_ The tendency •of the ordinary plain ferrule is to expand the tube tightly -at the-fire-side of the tube plate only and, quite possibly, there will be a space on the water side of the tube plate 'between the outaid of.the tube and the hole in the plate:. If trouble is experienced in getting sufficient steam, the tulyes should be examined to, see that they are .lean, and should be thbemighly brushed out to free them from soot. Then, the internal condition of the boiler should be investigated in order to be sure that there is not an• undue amount of -scale adhering. If the trouble does not lie here, theexhaust cone should be examined, as it may have lot clogged up with burnt oil from the engine, or, by some means, the exhaust pipe may have got out of place, so that the jet does.not register correctly with the centre ef the chimney. Further, the srnokebox door should be examined, as it may have become warped and be letlug air in round the joints, which will impair the effect of the draught on the fire, the air that is being drawn in through the badly fitting smokebox -door being substituted for that which, rightly, should be drawn through the fuel bed. The result will be a sluggish fire and want of steam.
In order to avoid sediment in the boiler as much as possible, great care should be exercised when picking up .water by the roadside from ponds or shalIow brooks. In • order to prevent grit and mud being drawn into the boiler with the water, the suction rose at the end of 'the hosepipe should not be allowed to lie directly on the bottom of the stream or pond.