In regard to (_c_), pipes, it is enacted that:

1. Mains for acetylene must be separated from the generating apparatus by a c.o.c.k, and under a five-minute test for pressure must not show a fall of over eight-tenths inch when the pressure is 13.8 inches, or three times the working pressure, whichever is greater.

2. The pipes must as a rule be of iron, though lead may be used where they are uncovered and not exposed to risk of injury. Rubber connexions may only be used for portable apparatus, and attached to a terminal on the metal pipes provided with a c.o.c.k, and be fastened at both ends so that they will not slip off the nozzles.

In regard to (_d_), residues, it is enacted that special open or well-ventilated pits must be provided for their reception when the apparatus exceeds 300 litres per hour productive capacity. With smaller apparatus they may be discharged into cesspools if sufficiently diluted.

The ITALIAN GOVERNMENT regulations in regard to acetylene plant are divided into eight sections. The first of these relates to the production and use of liquid and compressed acetylene. The production and use of liquid acetylene is prohibited except under the provisions of the laws relating to explosives. Neat acetylene must not be compressed to more than l-1/2 atmospheres except that an absolute pressure of 10 atmospheres is allowed when the gas is dissolved in acetone or otherwise rendered free from risk. Mixtures of acetylene with air or oxygen are forbidden, irrespective of the pressure or proportions. Mixtures of acetylene with hydrocarbons, carbonic oxide, hydrogen and inert gases are permitted provided the proportion of acetylene does not exceed 50 per cent. nor the absolute pressure 10 atmospheres.

The second section relates to acetylene installations, which are cla.s.sified in four groups, viz., (_a_) fixed or portable apparatus supplying not more than thirty burners consuming 20 litres per hour; (_b_) private installations supplying between 30 and 200 such burners; (_c_) public or works installations supplying between 30 and 200 such burners; (_d_) installations supplying more than 200 such burners.

The installations must comply with the following general conditions:

1. No part of the generator when working at its utmost capacity should attain a temperature of more than 100 C.

2. The carbide must be completely decomposed in the apparatus so that no acetylene can be evolved from the residue. The residues must be diluted with water before being discharged into drains or cesspools, and sludge storage-pits must be in the open.

3. The apparatus must preclude the escape of lime into the gas and water connexions.

4. Gla.s.s parts must be adequately protected.

5. Rubber connexions between the generator, gasholder, and main are absolutely prohibited with installations supplying more than 30 burners.

6. c.o.c.ks must be provided for cutting off the main and connexions from the generator and gasholder.

7. Each burner must have an independent tap.

8. Generators of groups (_b_), (_c_), and (_d_) must be constructed so that no after-generation of acetylene can take place automatically and that any surplus gas would in any case be carried out of the generator house by a vent-pipe.

The third section deals with generator houses, which must be well ventilated and light; must not be used for any other purpose except to store one day's consumption of carbide, not exceeding 300 kilos.; must be fire-proof; must have doors opening outwards; and the vent-pipes must terminate at a safe place in the open. Apparatus of group (_b_) must not be placed in a dwelling-room and only in an adjoining room if the gasholder is of less than 600 litres capacity. Apparatus of group (_c_) must be in an independent building which must be at least 33 feet from occupied premises if the capacity of the gasholder is 6000 litres and upwards. Half this distance suffices for gasholders containing 600 to 6000 litres. These distances may be reduced at the discretion of the local authorities provided a substantial part.i.tion wall at least 1 foot thick is erected. Apparatus of group (_d_) must be at least 50 feet from occupied premises and the gasholder and generator must not be in the same building.

The fourth section deals with the question of authorisation for the installation of acetylene plant. Apparatus of group (_a_) may be installed without obtaining permission from any authorities. In regard to apparatus of the other groups, permission for installation must be obtained from local or other authorities.

The fifth section relates to the working of acetylene plant. It makes the concessionaires and owners of the plant responsible for the manipulation and supervision of the apparatus, and for the employment of suitable operators, who must not be less than 18 years of age.

The sixth section relates to the inspection of acetylene plant from time to time by inspectors appointed by the local or other authorities.

Apparatus of group (_a_) is not subject to these periodical inspections.

The seventh section details the fees payable for the inspection of installations and carbide stores, and fixes the penalties for non- compliance with the regulations.

The eighth section refers to the notification of the position and description of all carbide works, stores, and acetylene installations to the local authorities.

The HUNGARIAN GOVERNMENT rules for the construction and examination of acetylene plant forbid the use of copper and of its alloys; c.o.c.ks, however, may be made of a copper alloy. The temperature in the gas s.p.a.ce of a fixed generator must not exceed 50 C., in that of a portable apparatus 80 C. The maximum effective pressure permissible is 0.15 atmosphere.

The CONSEIL D'HYGIeNE DE LA SEINE IN FRANCE allows a maximum pressure of 1.5 metres, i.e., 59 inches, of water column in generators used for the ordinary purposes of illumination; but apparatus intended to supply gas to the low-pressure oxy-acetylene blowpipe (see Chapter IX.) may develop up to 2.5 metres, or 98.5 inches of water pressure, provided copper and its alloys are entirely excluded from the plant and from the delivery- pipes.

The NATIONAL BOARD OF FIRE UNDERWRITERS OF THE UNITED STATES OF AMERICA has issued a set of rules and requirements, of which those relating to acetylene generators and plant are reproduced below. The underwriters state that, "To secure the largest measure of safety to life and property, these rules for the installation of acetylene gas machines must be observed."

RULES FOR THE INSTALLATION AND USE OF ACETYLENE GAS GENERATORS.

[Footnote: The "gallon" of these rules is, of course, the American gallon, which is equal to 0.83 English standard gallon.]

The use of liquid acetylene or gas generated therefrom is absolutely prohibited.

Failure to observe these rules is as liable to endanger life as property.

To secure the largest measure of safety to life and property, the following rules for the installation of acetylene gas machines must be observed.

_Cla.s.s A.--Stationary Automatic Apparatus._

1. FOUNDATIONS.--(_a_) Must, where practicable, be of brick, stone, concrete or iron. If necessarily of wood they shall be extra heavy, located in a dry place and open to the circulation of air.

The ordinary board platform is not satisfactory. Wooden foundations shall be of heavy planking, joists or timbers, arranged so that the air will circulate around them so as to form a firm base.

(_b_) Must be so arranged that the machine will be level and unequal strain will not be placed on the generator or connexions.

2. LOCATION.--(_a_) Generators, especially in closely built up districts should preferably be placed outside of insured buildings in generator houses constructed and located in compliance with Rule 9.

(_b_) Generators must be so placed that the operating mechanism will have room for free and full play and can be adjusted without artificial light. They must not be subject to interference by children or careless persons, and if for this purpose further enclosure is necessary, it must be furnished by means of slatted part.i.tions permitting the free circulation of air.

(_c_) Generators which from their construction are rendered inoperative during the process of recharging must be so located that they can be recharged without the aid of artificial light.

(_d_) Generators must be placed where water will not freeze.

3. ESCAPES OR RELIEF-PIPES.--Each generator must be provided with an escape or relief-pipe of ample size; no such pipe to be less than 3/4- inch internal diameter. This pipe shall be substantially installed, without traps, and so that any condensation will drain back to the generator. 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.

4. CAPACITY.--(_a_) Must be sufficient to furnish gas continuously for the maximum lighting period to all lights installed. A lighting period of at least 5 hours shall be provided for in every case.

(_b_) Generators for conditions of service requiring lighting period of more than 5 hours must be of sufficient capacity to avoid recharging at night. The following ratings will usually be found advisable.

(i) For dwellings, and where machines are always used intermittently, the generator must have a rated capacity equal to the total number of burners installed.

(ii) For stores, opera houses, theatres, day-run factories, and similar service, the generator must have a rated capacity of from 30 to 50 per cent, in excess of the total number of burners installed.

(iii) For saloons and all night or continued service, the generator must have a rated capacity of from 100 to 200 per cent. in excess of the total number of burners installed.

(_c_) A small generator must never be installed to supply a large number of lights, even though it seems probable that only a few lights will be used at a time. _An overworked generator adds to the cost of producing acetylene gas_.

5. CARBIDE CHARGES.--Must be sufficient to furnish gas continuously for the maximum lighting period to all burners installed. In determining charges lump carbide must be estimated as capable of producing 4-1/2 cubic foot of gas to the pound, commercial 1/4-inch carbide 4 cubic feet of gas to the pound, and burners must be considered as requiring at least 25 per cent. more than their rated consumption of gas.

6. BURNERS.--Burners consuming one-half of a cubic foot of gas per hour are considered standard in rating generators. Those having a greater or less capacity will decrease or increase the number of burners allowable in proportion.

Burners usually consume from 25 to 100 per cent. more than their rated consumption of gas, depending largely on the working pressure. The so- called 1/2-foot burner when operated at pressures of from 20- to 25- tenths inches water column (2 to 2-1/2 inches) is usually used with best economy.

7. PIPING.--(_a_) Connexions from generators to service-pipes must be made with right and left thread nipples or long thread nipples with lock nuts. All forms of unions are prohibited.

(_b_) Piping must, as far as possible, be arranged so that any moisture will drain back to the generator. If low points occur of necessity in any piping, they must be drained through tees into drip cups permanently closed with screw caps or plugs. No pet-c.o.c.ks shall be used.

(_c_) A valve and by-pa.s.s connexion must be provided from the service-pipe to the blow-off for removing the gas from the holder in case it should be necessary to do so.