PART XI.
Governor or Regulating Guage.
The governor or regulating guage, the construction of which has already been detailed, [page 171], we shall here consider as an instrument by means of which the gas flames of lamps and burners are kept of one steady and uniform magnitude.
The velocity of the gas in the mains and pipes of supply, is in the first instance as various as there are differences in the altitude and extent of the mains and pipes of supply. A main, at one place will furnish with a certain pressure of gas, a flame one inch high, while at a different altitude it will furnish a flame double that height.
If again the direction of the pipe has many turns or angles, and contractions, the velocity of the gas will be different on that account, than if it were direct and uniform. And if the pipe is of any great length, and of an uniform bore, but unequally furnished with veins or branch pipes at certain parts, the burners will be very unequally supplied with gas, those which are near its head will be supplied with a fuller stream of gas, than those which are situated towards its termination.
And independent of these differences thus arising from diversity of local positions, there will always be one grand variety in the velocity of the gas, occasioned by the variety of periods during which lights are required by different individuals supplied from the same main or system of pipes, as for example: when a certain number of burners are to be supplied, and it happens that one half of these burners are shut sooner than the rest, then in consequence of this, the velocity of the gas in the mains will be materially altered.
The inequality thus occasioned, may be seen particularly exemplified in the case of houses situated in the vicinity of any large establishment, such as either of the great theatres of the metropolis, and supplied with gas from the same mains. While the theatres are open, the lights in the adjacent houses are low and feeble, often too much so for the necessary purposes of the consumer, but the moment the theatres are shut, the great quantity of gas which they previously carried off, being transferred to such of the private houses as continue to be lighted, the gas flames at the latter are raised to an extravagant height, and burn with an intensity which makes the gas light partake more of the character of a nuisance than of a benefit.
It may be necessary for the better appreciation of the extent of this nuisance to observe, that it does not arise merely from the excess of light produced, but from the imperfect combustion of the gas, and hence a disagreeable odour is produced. When the flame is suffered to rise beyond the standard height, the combustion of the gas becomes imperfect, part of the gas passes through the flame unburnt, and occasions the source of the offensive odour alluded to, which the gas lights never produce when the combustion of the gas is complete. The remedy for all these inconveniences thus resulting from the various degrees of velocity of the gas in the mains, is to be found in the instrument now under description.
The effect of this machine, as already mentioned, is, that it causes the gas to issue from the aperture of the burners or lamps with one uniform velocity, whatever may be the variations which take place in the pressure which urges the gas to pass through the pipes of supply. And such is the efficiency of the operation of the machine, that it regulates the flow of the gas through any burner, tube, or opening, with a greater degree of exactness, than the centrifugal apparatus, regulates the action of the steam engine.
The construction of the regulator to effect this purpose is precisely similar to the apparatus already described, [page 171]. When applied for regulating the magnitude of the gas flames, it is of course usually made much smaller, of iron plates, japanned within and without. Fig. 4, [plate III.], exhibits a perspective view of the machine; a, is the inlet pipe, b, the outlet pipe; P, is the regulating cone, passing through the regulating aperture x, T. The floating vessel u, x, y, z, receives the gas introduced into the machine; A, B, C, D, is the outer air tight case of the regulator.
Directions to Workmen for fixing the Governor and Gas Metre.[49]
[49] Copied from Messrs. Clegg’s and Crossley’s printed directions to workmen, for fixing governors and gas metres.
The governor must be fixed perpendicularly, so as to admit its floating vessel u, x, y, z. Fig. 4, [plate III.], or fig. 9, [plate III.], to be taken out of the outer case of the machine if occasion should require it.
The gas enters into the machine from the street mains at the lowest branch a, and passes out of the machine by its highest branch b.
In connecting the pipes of supply, particular care must be taken that the work is not bound, or the governor by any means rendered leaky. It must be filled with water to the top of the central tube.
Examine the workmanship of the machine to see that it is perfect, and that the regulating cone P, is firmly secured to the top of the floating vessel and well centered. The floating vessels u, x, y, z, should clear the sides of the outer case of the apparatus by a quarter of an inch; and when sunk down, it should rest even upon the top of the central pipe, which conducts the gas into, and out of, the machine. The aperture in which the cone moves will then be at its widest opening, and when the floating vessel u, x, y, z, has risen to its highest elevation, the regulating aperture x, T, will be closed.
In this situation particular attention must be paid, that the regulating cone does not stick or rub in any part, but that it descends freely.
To the lower extremity of the floating vessel u, x, y, z, may be adapted an air vessel for the purpose of reducing the pressure of the gas.
The governor must be so fixed, that the water which may condense in the pipes leading to the burners shall drain back to the street mains, in order that it may not accumulate in the machine so as to impede its operations; for this purpose the gas pipes should have a fall of half an inch in three or four feet.
When the locality of situation will not admit of the water that may accumulate in the pipes falling back to the mains, its accumulation within the governor above the proper level of the water is prevented by an inverted siphon affixed to the machine, which allows the water to drain off without any escape of the gas.
The governor must be firmly fixed to the nearest beam or wall, as the least vibration will render the lights connected with it unsteady.
When a situation cannot be obtained sufficiently warm to prevent the water from freezing, the machine must then be wrapped round with woollen cloth, or any other bad conductor of heat. The cellar where the gas enters the house, has generally been found the most convenient situation.
For supplying any deficiency of water which the governor may require; a small funnel with a curved tube is placed for this purpose at the top of the governor. When the governor is filled to its proper height, the water will begin to run out of the siphon.
The mode of regulating the height of the flames will be stated presently.
Fig. 11, [plate III.], exhibits a portable governor or regulating guage, combined with a gas metre in one case. A, is the inlet pipe which conveys the gas into the machine, and B, is the pipe leading from the governor to the lamps or burners. D, a label expressing the quantity of gas discharged by one revolution of the wheel, and the number of lights which the metre is capable of supplying when the pressure of the gas in the inlet pipe is of a density sufficient to support a column of water of half an inch in height.
In those situations where the pressure of the gas is equal in density to support only a column of water one-quarter of an inch in height, a metre of a larger capacity must be adopted for supplying the same number of lights; and if the pressure of the gas be equal only to support a column of water one-eighth of an inch in height, the capacity of the metre must be still larger, and thus the capacity may be increased so as to equal every pressure that may occur. The index which registers the number of revolutions, and consequently the quantity of gas which passes through the metre, is shut up in the projecting case, near H, furnished with a lock and key.
Previously to the gas metre being filled with water, ascertain that the regulating cone is screwed perfectly air tight into the top of the floating vessel which receives the gas, and that the regulating aperture in which the cone moves, together with its spindle and guide rods, work perfectly free and without friction. Raise the floating vessel to its highest elevation, thereby closing the regulating aperture suddenly with the cone; in this situation it must not rub when turned and tried on every side, but descend with the least friction.
The gas metre and regulator being thus examined and fixed, the machine may be supplied with the requisite quantity of water in the following manner:
Open the stop-cock which admits the gas into the machine; open also the aperture E, which serves to show the pressure of the gas in the machine, and likewise the opening G, which lets out the air whilst water is poured in at the aperture H. The superfluous quantity of water will run out by the siphon tube at K.
Pour water also into the governor until it runs out at the aperture at M; and when this has been accomplished, till the gas metre with water at the opening H, until it overflows at the aperture K, when the surface of the water will appear at the cypher line on the scale board. The apertures F, G, H, K, and M, may then be closed, and the machine is ready for action.
Near to N, is an aperture communicating with the stuffing box in which the axis of the machine moves, and through which it should occasionally be supplied with a small portion of melted tallow.
To adjust the height of the gas flames of the burners, so that they be all uniform, open the stop-cock which admits the gas into the metre, and open also the stop-cocks of the burners, and as soon as the air has become discharged by means of one or two revolutions of the metre, light all the burners. Adjust the height of the flames in the first instance by their stop-cocks, that they become all of an equal height, which should be about double the diameter of the flame; if any of the flames be too low when the stop-cock is fully open, a small weight must be placed upon the top of the floating vessel of the regulator, sufficient to produce the required flame at the burner, and then again adjust the remaining lights by their stop-cocks as before stated; this being done, the aperture to which each burner is screwed must be sufficiently narrowed, that it will admit no more gas than is requisite for the required height of the flame, when the stop-cock is fully open. The diminution of the aperture of the stop-cock may be effected by a brass plug fitted into it, with a hole in its centre, which must be gradually widened with a drill until the flame has required the proper height. It is recommended, instead of adding weight to the floating vessel of the regulator, that the tubes which supply the gas be sufficiently capacious to render the weight unnecessary.
The burners should also be examined from time to time. Observe that the plugs, sockets, and every other part of the gas metre and regulator be air tight, and that there be no escape of water or gas.
An escape of gas, either from the metre or from any of the tubes or burners, will be discovered by looking at the index of the metre, as the wheel cannot fail to move whenever there is an escape of gas, if the stop-cock is open which supplies the gas to the metre. The place where the gas escapes will be found in the usual way, either by the odour which the gas produces, or by passing a lighted taper over the apertures and connections of the metre, and along the tubes leading to the burners, which will cause the gas to take fire at the place where the leak happens to be.
The following remarks will assist the workmen in correcting any irregularities which may occur in the lights connected with the apparatus.
A diminution, or extinction of the lights, may be occasioned by a deficiency of water in the gas metre or regulator; when this occurs the necessary quantity of water must be supplied as before directed up to the cypher line on the scale board E, of the metre, and opening the aperture M, where it may be seen when the water has risen to the proper height in the governor.
A diminution of light may also be occasioned by some obstruction or contraction of the tubes which supply the gas, or by a diminution of the pressure of the gas in the mains, to which the metre was originally adjusted.
When the lights increase above their standard height, and are variable with the changes in the pressure or velocity of the gas in the mains or tubes of supply within the house or place, lighted, there is then reason to believe that the governor is not performing, which may arise from the following causes. Its floating vessel u, x, y, z, may have become fast by the friction of the spindle or guide rod, requiring cleaning, or by an accumulation of water in the air-vessel of the floating vessel u, x, y, z. The water may be drained off at a small plug by taking out the floating vessel. The same inconvenience would arise from a diminution in the proper level of the water.
In order to ascertain that the governor performs correctly, observe at the time of lighting or extinguishing any of the burners connected with it, that its floating vessel rises and falls every time the stop-cock is opened, and that the lights do not suffer any material change.
An instantaneous starting or dancing of the lights, is generally occasioned by an accumulation of water in the tubes through which the gas passes; if this should happen in the vicinity of the metre and governor, it may be drained off at the aperture K. A provision for a like purpose is also made at the bottom of the governor when detached from the metre.
In order at any time to ascertain the pressure of the gas in the metre, close the stop-cock which admits the gas, and open the aperture G and F, which will shew the level of the water on the scale board E. This being first observed, close the aperture G, and open the stop-cock, and the pressure of the gas in the metre will be indicated by the rise of the water on the scale board E, above its original height.