Laying out an acetylene plant in India: PESO distances single-storey compressor house, outward doors, light roof, ventilation, lighting and sludge pits

Most of what makes an acetylene plant safe is decided before a single vessel is ordered — by where the buildings stand, how far apart they are, how they are built and how they breathe. In India the distances are set by PESO in Form E of the Gas Cylinders Rules 2016, and the building rules come from IS 15190 Part 2 and long-standing international practice. This page sets out both, explains the reasoning behind each, and compares the Indian distances with the European code that a multinational customer's auditor will bring.

Form E Part B of the Gas Cylinders Rules 2016, reproduced in PESO's licensing guidelines, is the table an Indian acetylene plant is licensed against:

Form F adds 3 m of clear space all round a flammable-gas cylinder shed, with industrial fencing at least 2 m high. Rule 47(1)(a)(iii) requires the licensing plan to show everything within 100 m.

The 30 m and 90 m figures are the distinctive ones. They protect against acetylene being drawn into an oxygen plant or an air-compressor intake and carried into compressed-air systems or liquid-oxygen equipment. EIGA Doc 123 Table 6, the European comparator, has no such entries, so PESO is stricter on this axis. EIGA, for its part, requires 200 m from a filling building to public buildings with large gatherings — schools, hospitals, railway stations — a far-field rule PESO does not state. AIGA 022/13, the Asian code reproduced from EIGA's with permission, notes that local legislation takes precedence, so PESO governs in India; but a site that meets PESO alone may still be questioned by a European auditor.

The CPI code's eight building rules remain the best short statement of the details. Walls, floors and ceilings are non-combustible. Doors open outwards, are light enough to move easily and let fresh air into the lower part of the room; a large sliding or lifting door carries a small outward-opening wicket so people can get out. Where ventilation is natural, there are non-closing openings at floor level and in the ceiling — both, because acetylene's relative density of 0.906 at 15 °C (IS 14814:2023) is close enough to air that it neither reliably rises nor reliably sinks, though in still air it collects under the roof. The lighter than air page explains the numbers. Lighting is good enough to see leaks and defects, with at least 60 lux at work level in the compression and loading shop. Floors in dry climates are semi-conducting, all equipment is earthed and staff do not wear rubber-soled shoes. Premises have a lightning-protection installation. EIGA Doc 123 adds a maximum travel distance to an exit of 25 m and a maximum heating-surface temperature of 225 °C.

The generator house is built of fire-resisting materials, ventilated thoroughly so released acetylene cannot accumulate, and isolated from workshops and offices. Daylight is used as far as possible, and any electrical equipment is arranged so that an acetylene atmosphere cannot ignite on it — which in India means flameproof Group IIC equipment, or equipment moved outside behind a gastight wall, as discussed on the Group IIC page. Relief and over-production pipes from generator and gasholder discharge outside into the open air at a safe point, cannot choke, can be checked, and are protected from weather, birds and insects. NFPA 51A-1984, the US standard for charging plants (cited here for comparison only; it is not Indian law), puts relief vent outlets at least 12 ft (3.6 m) above ground and 3 ft (0.9 m) from combustible construction; IS 15190 Part 2 puts safety-valve vents at 5 m height clear of the building.

Carbide lime leaves the generator carrying dissolved acetylene, which outgasses as the liquor cools and settles. The CPI code required drainage pipes, at least over part of their length, and the decanting trenches to be open to the air so that no explosive atmosphere forms in a closed container; the German practice it reflected sited pits so gas could not drift indoors. PESO's 9 m from drying pits to boundary and generator is the Indian minimum. NFPA 51A-1984 forbids continuous drain connections to sewers and puts the discharge point at least 15 ft (4.5 m) from ignition sources and buildable property. Handling of the sludge itself is on the carbide lime sludge page.

The carbide store is separate, dry, waterproof and well ventilated, with containers raised off the ground and no water, steam or condensate lines in the room. EIGA puts it at least 3 m from the boundary and offices; NFPA 51A at least 10 ft (3 m) from buildable property. Empty drums are stored outside the manufacturing premises.

The CPI code required hydrants outside the buildings with adequate pressure and delivery, alarms to warn staff and to call the fire brigade, and at least two extinguishers in every important building, placed where operators can reach them. Form E of the Gas Cylinders Rules 2016 requires a deluge system and dry chemical powder extinguishers at strategic locations; EIGA Doc 123 specifies deluge at 10 l/m² per minute with 90 minutes' supply normally and 12 hours for a hot-cylinder incident. Hydrant valves and deluge actuators belong at exits so they can be worked from outside, and the carbide store is the one area where water is not used.