IS 4379 gas cylinder colour codes in India gas by gas

What IS 4379 actually does

IS 4379:1981, Identification of the Contents of Industrial Gas Cylinders, is the Indian Standard that tells you what is inside a cylinder by how it is painted. It is referenced by the Gas Cylinders Rules and it applies to industrial cylinders. Medical cylinders are outside its scope and follow IS 3933 instead — a distinction that catches out a surprising number of otherwise careful buyers.

The standard works on two elements:

• Ground colour — the body of the cylinder.
• Neck band — a band around the shoulder, used where the ground colour alone would be ambiguous.

Colour names in the standard are tied to shade numbers from IS 5:1978, the ready-mixed paint standard. That is what makes the scheme reproducible between paint suppliers. “Maroon” is an opinion; shade 541 is a specification.

The colour table

The ground colours and bands for the gases in normal industrial circulation in India:

Gas	Ground colour	Neck band
Oxygen	Black	—
Dissolved acetylene	Maroon (541)	—
Hydrogen	Signal red (537)	—
Nitrogen	French grey (630)	Black
Carbon dioxide	Black	White or aluminium
Argon	Peacock blue (103)	—
Helium	Middle brown (411)	—
Compressed air	French grey (630)	—
Ammonia	Black	Signal red + golden yellow
LPG, methane, propane, butane	Signal red (537)	—

Where a cylinder carries two bands, the order is fixed: the red or blue band sits nearest the valve, with yellow between. Any band must be at least a quarter of the cylinder’s outside diameter in width, so that it reads at a distance.

The black-cylinder problem

Look at the table again. Oxygen and carbon dioxide are both black. The only thing separating them on the paintwork is a white neck band on the CO₂ cylinder — a band that fades, gets overpainted during refurbishment, and disappears entirely under a coat of workshop grime.

This is the most consequential ambiguity in the Indian scheme, and it deserves to be treated as a live hazard rather than a curiosity:

• Carbon dioxide connected where oxygen was expected will not support combustion — a cutting set will not light, which is the harmless failure.
• The dangerous failure is the reverse, or a medical application, where the consequence is not a flame that will not light.

The practical rule in every plant we supply is the same: colour tells you where to look, the stamping tells you what it is. IS 4379 requires the cylinder to be marked with the gas name and chemical formula, and every cylinder carries stamped identification on the shoulder. Read it. Then read the label. Colour is the third check, not the first.

Why the international colours are different

If you have handled imported cylinders, or worked to ISO or EN practice, the table above will look wrong — under the ISO harmonised scheme oxygen is white, not black.

Both are correct in their own jurisdiction. India runs the IS 4379:1981 scheme, and the cylinders in circulation here — including ours — are painted to it. A later edition of IS 4379 moves toward the ISO colours, but the installed fleet across the country reflects the 1981 edition and will for years, because cylinders last decades and repainting a national fleet is not a thing that happens quickly.

Two consequences worth planning for:

1. A mixed fleet is normal. If you buy from more than one supplier, or take in imported cylinders, you will eventually hold cylinders painted to two different conventions at the same time. Procedure must be written around the marking, not the paint.
2. Do not repaint to “correct” a cylinder. Repainting a cylinder to the colour you think it ought to be is how a genuinely mislabelled cylinder gets created. Colour changes are the filler’s job, made at the same time as the markings.

Colour is not a specification

A last point, because it is the one that causes arguments on delivery.

Colour identifies the gas. It says nothing about the grade. An industrial oxygen cylinder and a higher-purity oxygen cylinder are painted identically. Dissolved acetylene at ≥98 % to IS 308 and ultra-high-purity acetylene at 99.99 % in DMF are both maroon. If your process is purity-sensitive — atomic absorption, analysis, medical use — the paint will never tell you what you need to know. The batch certificate will.

How KIGL applies it

Every cylinder we fill leaves painted to IS 4379, marked with the gas name and formula, and labelled with the grade and batch reference. Our cylinder tracking system holds the colour, the specification, the test date and the fill record against each individual cylinder’s serial number, which is how we can answer “what is actually in this one” without relying on what somebody painted on it years ago.

For the standards that govern how those cylinders are built, valved and tested, see the standards index.