Part 7 (1/2)

3/8 inch pipe 26 feet long 2 cubic feet per hour

1/2 inch pipe 30 feet long 4 cubic feet per hour

3/4 inch pipe 50 feet long 15 cubic feet per hour

1 inch pipe 70 feet long 27 cubic feet per hour

1-1/4 inch pipe 100 feet long 50 cubic feet per hour

1-1/2 inch pipe 150 feet long 65 cubic feet per hour

2 inch pipe 200 feet long 125 cubic feet per hour

2-1/2 inch pipe 300 feet long 190 cubic feet per hour

3 inch pipe 450 feet long 335 cubic feet per hour

When drainage is possible into a sewer, the generator should not be connected directly into the sewer but should first discharge into an open receptacle, which may in turn be connected to the sewer

No valves or pet cocks should open into the generator roo theas Any condensationparts, being drained into closed receptacles It should be needless to say that all the piping for gas th

_Safety Devices_--Good generators are built in such a way that the operatorand cleaning as well as in all other necessary care It has been as pressure is released or shut off before it is possible to fill the water co the generator inoperative and free fro the residue drain of the carbide filling opening on top of the hopper Soenerate should there be a sudden and abnoras such as would be caused by a bad leak Thisparts may be carried to any extent that seeenerators should be provided with escape or relief pipes of large size which lead to the open air These pipes are carried so that condensation will drain back toward the generator and after being led out of the building to a point at least twelve feet above ground, they end in a protecting hood so that no rain or solid as which enerator room is led into these escape pipes, all parts of the systeas will find this way out

Safety blow off valves are provided so that any excess gas which cannot be contained by the gas holderan undue rise in pressure This valve also allows the escape of pressure above that for which the generator was designed Gas released in this way passes into the escape pipe just described

Inasreater than that of the acetylene when used in the torch, it will be seen that anything that caused the torch outlet to becoen to force the acetylene back into the generator and the oxygen would follow it, as is prevented by a hydraulic safety valve or back pressure valve, as it is often called

Mechanical check valves have been found unsuitable for this use and those which employ water as a seal are now required by the insurance rules The valve itself (Figure 13) consists of a large cylinder containing water to a certain depth, which is indicated on the valve body Two pipes come into the upper end of this cylinder and lead down into the water, one being longer than the other The shorter pipe leads to the escape pipe enerator The upper end of the cylinder has an opening to which is attached the pipe leading to the torches

[Illustration: Figure 13--Hydraulic Back-Pressure Valve

_A_, Acetylene supply line; _B_, Vent pipe; _C_, Water filling plug; _D_, Acetylene service cock; _E_, Plug to gauge height of water; _F_, Gas openings under water; _G_, Return pipe for sealing water; _H_, Tube to carry gas beloater line; _I_, Tube to carry gas to escape pipe; _J_, Gas chah water level; _M_, Opening through which water returns; _O_, Bottoenerator through the longer pipe passes out of the lower end of the pipe which is under water and bubbles up through the water to the space in the top of the cylinder Fro to the torches The shorter pipe is closed by the depth of water so that the gas does not escape to the relief pipe As long as the gas flows in the normal direction as described there will be no escape to the air Should the gas in the torch line return into the hydraulic valve its pressure will lower the level of water in the cylinder by forcing some of the liquid up into the two pipes As the level of the water lowers, the shorter pipe will be uncovered first, and as this is the pipe leading to the open air the gas will be allowed to escape, while the pipe leading back to the generator is still closed by the water seal As soon as this reverse flow ceases, the water will again resume its level and the action will continue Because of the small amount of water blown out of the escape pipe each time the valve is called upon to perform this duty, it is necessary to see that the correct water level is always maintained

While there are modifications of this construction, the same principle is used in all types The pressure escape valve is often attached to this hydraulic valve body

_Construction Details_--Flexible tubing (except at torches), swing pipe joints, springs, mechanical check valves, chains, pulleys and lead or fusible piping should never be used on acetylene apparatus except where the failure of those parts will not affect the safety of the machine or peras into a room Floats should not be used except where failure will only render the machine inoperative

It should be said that the National Board of Fire Underwriters have established an inspection service for acetylene generators and any apparatus which bears their label, stating that that particular model and type has been passed, is safe to use This service is for the best interests of all concerned and looks toward the prevention of accidents

Such inspection is a very important and desirable feature of any outfit and should be insisted upon

_Location of Generators_--Generators should preferably be placed outside of insured buildings and in properly constructed generator houses

The operating mechanism should have ah for the attendant to reach the various parts and perform the required duties without hindrance or the need of artificial light They should also be protected fro by unauthorized persons

Generator houses should not be within five feet of any opening into, nor have any opening toward, any adjacent building, and should be kept under lock and key The size of the house should be no greater than called for by the requirements mentioned above and it should be well ventilated