562
GAS-LIGHT.
cylindrical vessel of cast iron i
the end of the gas pipe which comes from the purifiedimmersed a few inches deep into the liquid witwhich the vessel is about two thirds filled; bthe gas-pipe which leads into the gasometerc is a perpendicular tube, placed over the bo' 10 ?of the vessel, and reaching to wilhin one third 0the top, through which the liquid is introduce^491 into the vessel, and through which it escapes ,it overflows the level d. In this tube the 1*4°*stands towards the inner level higher, in prop 0tion to the pressure of the gas in the gason> ete ( jThe fluid which is condensed in the gas-pipe b, a ”in its prolongation from the gasometer, runs 0into the vessel A ; and therefore the latter must .laid so low that the said tube may have the re 9 ul j! e( |declivity. A straight stopcock may also be attac ^to the side over the bottom, to draw ofl'any sedi® e
II. Application of Light-Gas.
mail 1 '
1. Distribution of the pipes. —The pressure by which the motion of the gas is ^tained in the pipes, corresponds to a certain height of water in the cistern of the §® S j ve neter. From the magnitude of this pressure, and the quantity of gas which in 8 Stime, as an hour, must be transmitted through a certain length of pipes, depends .width or the diameter that they should have, in order that the motion may not be retaby the friction which the gas, like all other fluids, experiences in tubes, and thereb) ^gas might be prevented Lorn issuing with the velocity required for the jets of « ( j. eThe velocity of the gas in the main pipe increases in the ratio of the square root °pressing column of water upon the gasometer, and therefore by increasing this P re * t |, ethe gas may be forced more rapidly along the remoter and smaller ramifications o rpipes. Tims it happens, however, that the gas will be discharged from the orifices . #the gasometer, with superfluous velocity. It is therefore advisable to lay the r jj-such a manner, that in every point of their length the velocity of discharge may he nequal. This may be nearly effected as follows flr j,ich
From experiment it appears that the magnitude of the friction, or the resistance s |the air suffers in moving along the pipes, under a like primary pressure, that iSj.*° g e dinitial velocity, varies with the square root of the length. The volume of gas disc in-from the end of a pipe is directly proportional to the square of its diameter, ® cU bicversely as the square root of its length ; or, calling the length L, the diameter P, 111
P2 s th at
feet of gas discharged in an hour k; then k = — • Experience likewise show ,
’\/Ij _ |j
for a pipe 250 feet long, which transmits in an hour 200 cubic feet of gas, onea sufficient diameter.
1 D2
Consequently, 200 : k ;;-: =
144 V 250 vL
and D= \/k
455,000
From this formula the following table of proportions is calculated
Number of cubic feet per hour.
Length of pipe, in feet.
50
100
250
200
500
600
700
1000
1000
1000
1500
1000
2000
1000
2000
2000
2000
4000
2000
6000
6000
1000
6000
2000
8000
1000
8000
2000
Diameter,
These dimensions are applicable to the case where the body of gas is transnu