(_d_) The schedule of pipe sizes for piping from generators to burners should conform to that commonly used for ordinary gas, but in no case must the feeders be smaller than three-eighths inch.
The following schedule is advocated:
3/8 inch pipe, 26 feet, three burners.
1/2 inch pipe, 30 feet, six burners.
3/4 inch pipe, 50 feet, twenty burners.
1 inch pipe, 70 feet, thirty-five burners.
1-1/4 inch pipe, 100 feet, sixty burners.
1-1/2 inch pipe, 150 feet, one hundred burners.
2 inch pipe, 200 feet, two hundred burners.
2-1/2 inch pipe, 300 feet, three hundred burners.
3 inch pipe, 450 feet, four hundred and fifty burners, 3-1/2 inch pipe, 500 feet, six hundred burners.
4 inch pipe, 600 feet, seven hundred and fifty burners.
(_e_) Machines of the carbide-feed type must not be fitted with continuous drain connexions leading to sewers, but must discharge into suitable open receptacles which may have such connections.
(_f_) Piping must be thoroughly tested both before and after the burners have been installed. It must not show loss in excess of 2 inches within twelve hours when subjected to a pressure equal to that of 15 inches of mercury.
(_g_) Piping and connexions must be installed by persons experienced in the installation of acetylene apparatus.
8. CARE AND ATTENDANCE.--In the care of generators designed for a lighting period of more than five hours always clean and recharge the generating chambers at regular stated intervals, regardless of the number of burners actually used.
Where generators are not used throughout the entire year always remove all water and gas and clean thoroughly at the end of the season during which they are in service.
It is usually necessary to take the bell portion out and invert it so as to allow all gas to escape. This should never be done in the presence of artificial light or fire of any kind.
Always observe a regular time, during daylight hours only, for attending to and charging the apparatus.
In charging the generating chambers of water-feed machines clean all residuum carefully from the containers and remove it at once from the building. Separate from the mass any unslacked carbide remaining and return it to the containers, adding now carbide as required. Be careful never to fill the containers over the specified mark, as it is important to allow for the swelling of the carbide when it comes in contact with water. The proper action and economy of the machine are dependent on the arrangement and amount of carbide placed in the generator. Carefully guard against the escape of gas.
Whenever recharging with carbide always replenish the water-supply.
Never deposit residuum or exhausted material from water-feed machines in sewer-pipes or near inflammable material.
Always keep water-tanks and water-seals filled with clean water.
Never test the generator or piping for leaks with a flame, and never apply flame to an outlet from which the burner has been removed.
Never use a lighted match, lamp, candle, lantern or any open light near the machine.
Failure to observe the above cautions is as liable to endanger life as property.
9. OUTSIDE GENERATOR HOUSES.--(_a_) Outside generator houses should not be located within 5 feet of any opening into, nor shall they open toward any adjacent building, and must be kept under lock and key.
(_b_) The dimensions must be no greater than the apparatus requires to allow convenient room for recharging and inspection of parts. The floor must be at least 12 inches above grade and the entire structure thoroughly weather-proof.
(_c_) Generator houses must be thoroughly ventilated, and any artificial heating necessary to prevent freezing shall be done by steam or hot-water systems.
(_d_) Generator houses must not be used for the storage of calcium carbide except in accordance with the rules relating to that subject (_vide_ Chapter II.).
_Class B.--Stationary Non-Automatic Apparatus_.
10. FOUNDATIONS.--(_a_) Must be of brick, stone or concrete.
(_b_) Must be so arranged that the machine will be level and so that strain will not be brought upon the connexions.
11. GAS-HOUSES.--(_a_) Must be constructed entirely of non- combustible material and must not be lighted by any system of illumination involving open flames.
(_b_) Must be heated, where artificial heating is necessary to prevent freezing, by steam or hot-water systems, the heater to be located in a separate building, and no open flames to be permitted within generator enclosures.
(_c_) Must be kept closed and locked excepting during daylight hours.
(_d_) Must be provided with a permanent and effective system of ventilation which will be operative at all times, regardless of the periods of operation of the plant.
12. ESCAPE-PIPES.--Each generator must be provided with a vent-pipe of ample size, substantially installed, without traps. It must be carried to a suitable point outside the building and terminate in an approved hood located at least 12 feet above ground and remote from windows.
The hood must be constructed in such a manner that it cannot be obstructed by rain, snow, ice, insects or birds.
13. CARE AND MAINTENANCE.--All charging and cleaning of apparatus, generation of gas and execution of repairs must be done during daylight hours only, and generators must not be manipulated or in any way tampered with in the presence of artificial light.
This will require gasholders of a capacity sufficient to supply all lights installed for the maximum lighting period, without the necessity of generation of gas at night or by artificial light.
In the operation of generators of the carbide-feed type it is important that only a limited amount of carbide be fed into a given body of water.
An allowance of at least one gallon of generating water per pound of carbide must be made in every case, and when this limit has been reached the generator should be drained and flushed, and clean water introduced.
These precautions are necessary to avoid over-heating during generation and accumulation of hard deposits of residuum in the generating chamber.
(Rule 14, referring to the storage of carbide, has been quoted in Chapter II. (page 19)).
RULES FOR THE CONSTRUCTION OF GENERATORS.
The following Rules are intended to provide only against the more hazardous defects usually noted in apparatus of this kind. The Rules do not cover all details of construction nor the proper proportioning of parts, and devices which comply with these requirements alone are not necessarily suitable for listing as permissible for use. These points are often only developed in the examination required before permission is given for installation.
_Class A.--Stationary Apparatus for Isolated Installations._
15. GENERAL RULES. GENERATORS.--(_a_) Must be made of iron or steel, and in a manner and of material to insure stability and durability.
(_b_) Must be automatically regulated and uniform in their action, producing gas only as immediate consumption demands, and so designed that gas is generated without producing sufficient heat to cause yellow discoloration of residuum (which will occur at about 500 F.) or abnormal pressure at any stage of the process when using carbide of any degree of fineness.
The presence of excessive heat tends to change the chemical character of the gas and may even cause its ignition, while in machines of the carbide-feed type, finely divided carbide will produce excessive pressure unless provision is made to guard against it.
(_c_) Must be so arranged that during recharging, back flow of gas from the gasholder will be automatically prevented, or so arranged that it will be impossible to charge the apparatus without first closing the supply-pipe to the gasholder, and to the other generating chambers if several are used.
This is intended to prevent the dangerous escape of gas.
(_d_) The water or carbide supply to the generating chamber must be so arranged that gas will be generated long enough in advance of the exhaustion of the supply already in the gasholder to allow the using of all lights without exhausting such supply.
This provides for the continuous working of the apparatus under all conditions of water-feed and carbide charge, and it obviates the extinction of lights through intermittent action of the machine.