Gas Cylinder Identification: Colour Codes, Labels & Markings in the UK and Europe
Gas cylinder identification should start with the product label, not the cylinder colour.
For industrial users in the UK and Europe, colour coding is a useful visual aid, but it is not the main way to confirm what a cylinder contains. The written product label comes first. Permanent markings provide information about the cylinder itself, while shoulder colour can help with quick recognition.
A good gas cylinder identification check is straightforward. Read the label, confirm the gas or mixture, review the hazard and transport information, check the permanent markings, and use the shoulder colour only as secondary confirmation.
This approach is especially important in workplaces that receive different gases, mixtures or cylinder types from more than one supplier.
Table of Contents
How should you identify a gas cylinder?
Accurate gas cylinder identification starts with the written product label.
Check the gas or mixture name and make sure it matches the product required for the application. Then review the related hazard and transport information. Permanent markings and shoulder colour can support that check, but neither should replace the label.
| Identification feature | What it tells you | Role |
|---|---|---|
| Product label | Gas or mixture identity, hazards and transport information | Primary identification |
| UN number and danger labels | Dangerous-goods classification and transport identity | Supporting information |
| Permanent markings | Information about the cylinder as a pressure receptacle | Not a substitute for the label |
| Shoulder colour | A specific gas or a general gas-property group | Secondary visual aid |
| Cylinder body colour | May follow a defined exception or an owner or supplier scheme | Usually not enough on its own |
| Valve guard or cap colour | May follow a supplier scheme | Not a reliable gas identifier |
If a cylinder looks different from what you expected, do not assume the colour is correct and the label is wrong. Stop and confirm the product with the supplier or cylinder owner.
BCGA states that every individual gas cylinder should carry a label identifying its contents and describes the label as the primary and mandatory method of identification. Colour coding is secondary.
What information is on a gas cylinder label?
A gas-cylinder label carries more than the gas name.
BCGA Technical Information Sheet 6 explains that a typical label can include the primary and subsidiary danger labels, UN number, proper shipping name, product name where required, signal word, hazard and precautionary statements, package size and pressure, and supplier details.
For industrial users, reliable gas cylinder identification depends on keeping this label present, readable and matched to the intended product.
When cylinders arrive on site, the receiving team should confirm that the gas or mixture matches the purchase order, the label can be read clearly, and the specified product or grade is correct for the process.
A damaged, missing or unreadable label should not be replaced by assumptions based on colour.
What do permanent gas cylinder markings mean?
Permanent markings serve a different purpose from the product label.
They relate mainly to the cylinder as a pressure receptacle. Depending on the cylinder type and service, the markings may provide information about manufacture, approval, capacity, pressure, inspection or periodic testing.
Permanent markings support gas cylinder identification, but they should not be confused with the product label.
The easiest way to separate the two is to think of the product label as information about the contents and the permanent markings as information about the cylinder.
For more detail on conformity and cylinder standards, see Northline’s EU certification standards for industrial gas cylinders guide.
How does gas cylinder colour coding work?
Gas cylinder colour coding is applied mainly to the shoulder, which is the curved upper section of the cylinder.
BS EN 1089-3:2011 sets out a colour-coding system used as a secondary method of identifying cylinder contents within its scope. BSI also notes that regulatory labelling and marking requirements under RID and ADR take precedence.
You can review the standard overview on BSI’s BS EN 1089-3:2011 page.
In practice, gas cylinder identification combines written labelling with this secondary visual system.
Some gases have a specific assigned colour. Where no specific gas colour applies, a generic shoulder colour can indicate a property of the gas.
| Gas property | Shoulder colour |
|---|---|
| Inert | Bright green, RAL 6018 |
| Oxidising | Light blue, RAL 5012 |
| Flammable | Red, RAL 3000 |
| Toxic and/or corrosive | Yellow, RAL 1018 |
BCGA also notes that colour coding is generally not mandatory, apart from the specific acetylene requirement, although where colour coding is used it follows the established identification system.
These colours help with recognition. They do not remove the need to read the product label.
Gas cylinder identification colour chart
A gas cylinder identification chart can be useful for quick recognition, provided the colour is always checked against the written label.
For several common industrial gases, current UK guidance gives the following specific colours. Unless stated otherwise, the colour applies to the cylinder shoulder.
| Gas | Formula | UK colour identification |
|---|---|---|
| Oxygen | O₂ | White, RAL 9010 |
| Nitrous oxide | N₂O | Blue, RAL 5010 |
| Argon | Ar | Dark green, RAL 6001 |
| Nitrogen | N₂ | Black, RAL 9005 |
| Carbon dioxide | CO₂ | Grey, RAL 7037 |
| Helium | He | Brown, RAL 8008 |
| Acetylene | C₂H₂ | UK: Black Red, RAL 3007, body and shoulder |
The current BCGA technical sheet confirms these specific colour values.
The chart is a reference aid. It should not be used to identify an unknown cylinder from colour alone.
Why acetylene is different
Acetylene needs a separate explanation because UK requirements apply the specified colour to more than the shoulder.
In the UK, both the body and shoulder of an acetylene cylinder are required to be Black Red, RAL 3007.
Cylinders originating elsewhere in Europe may instead use Oxide Red, RAL 3009, which is the acetylene colour designated in BS EN 1089-3. Both colours are commonly described as maroon.
This difference is useful to understand when a business receives cylinders from more than one European market.
It also shows why a simple internet colour chart is not enough for professional cylinder identification.
Why cylinder body colour can be misleading
For most industrial gas cylinders, there is no universal body-colour scheme.
BCGA identifies three important exceptions:
- acetylene cylinders
- medicinal-gas cylinders
- hydrogen cylinders
Acetylene follows the specific requirement described above. Medicinal-gas cylinders use a white body under the applicable policy, while hydrogen cylinders should have the body and shoulder coloured red, RAL 3000.
For other cylinders, the gas company or cylinder owner may select a body-colour scheme within the applicable rules.
That means the complete body colour of a nitrogen, argon or helium cylinder can vary between suppliers.
The written label remains the primary reference.
Cross-border gas cylinder identification should therefore rely on written product information rather than complete body colour alone.
What about gas mixtures?
Gas mixtures can be more complicated than single gases.
Where more than one property needs to be represented, shoulder colours may be arranged using bands or quadrants. BCGA notes that there is no single specific colour arrangement in the standard for every possible gas mixture, so different gas suppliers may use their own preferred system.
The product label and ordered specification therefore become particularly important for welding mixtures, laboratory mixtures and process gases.
If a process requires a defined mixture or purity, confirm the stated product specification rather than relying on a familiar colour combination.
For broader industrial and process-gas requirements, see Northline’s Technical Gases page.
What does a UN number on a gas cylinder mean?
A UN number is a four-digit identifier used within dangerous-goods transport systems.
On a cylinder label, it appears with the relevant shipping and hazard information. BCGA identifies the UN number, proper shipping name and danger labels as separate elements on the cylinder label.
A UN number is useful identification and transport information, but it should be read as part of the complete label rather than used on its own.
For a receiving team, checking the product name, UN number and danger information together is more reliable than making a decision from cylinder appearance.
What do the diamond danger labels mean?
Diamond labels show the primary dangerous-goods hazard and, where relevant, subsidiary hazards.
Depending on the product, the labels can indicate risks associated with gases that are non-flammable, oxidising, flammable, toxic or corrosive.
Cylinders with similar dimensions can contain gases with very different properties. The danger information on the label therefore matters for handling, transport and storage decisions.
BCGA’s example label also shows that the dangerous-goods classification information sits alongside the UN number, proper shipping name and other product information.
Should the valve guard or protection cap match the gas colour?
Not necessarily.
BS EN 1089-3 does not require valve guards or protection caps to be colour coded.
Where they are coloured, BCGA says the colour should align with the designated shoulder colour. If another colour is used, it should not conflict with the shoulder colour.
For that reason, the colour of a cap or guard should not be used to decide what a cylinder contains.
The same principle applies to the apparent valve arrangement. Equipment connections provide useful technical information, but they are not a replacement for reading the product label.
How are cylinder bundles and packs identified?
Businesses with higher gas demand may receive cylinders in bundles or packs instead of individual units.
Colour coding of cylinders in bundles or packs is not a requirement of BS EN 1089-3.
Correct labels, transport information and supply documentation are therefore especially important for larger supply formats.
The colour of the bundle frame should not be treated as proof of the gas or mixture inside.
For more information on cylinder capacity and common supply formats, see Northline’s Gas Cylinder Sizes guide.
Do UK and European gas cylinders always look the same?
No.
BS EN 1089-3 provides a harmonised colour-coding framework, but visual differences can still occur between suppliers, applications and countries.
Body colours can vary. Gas mixtures may use different permitted arrangements. Acetylene has a specific UK distinction. Cylinders that have moved between markets can also look different from those a site normally receives.
For businesses operating across Europe, the written product label is the consistent reference point.
This is why gas cylinder identification should be based on the complete identification information rather than a colour remembered from one supplier.
Does BS EN 1089-3 apply to LPG cylinders?
No.
BSI states that BS EN 1089-3 does not apply to LPG cylinders.
Its scope also excludes refrigerant-gas cylinders, portable fire extinguishers and stationary cylinder extinguishing systems.
An LPG cylinder should therefore not be interpreted using an industrial-gas colour chart intended for BS EN 1089-3.
What should you do if a cylinder label is missing or unreadable?
Do not guess the contents from colour.
An unidentified cylinder should not be connected to equipment simply because its shoulder, body or valve resembles another cylinder normally used at the site.
BCGA storage guidance states that where the contents cannot be positively identified, the cylinder should be quarantined within the gas store and the cylinder owner contacted for further advice.
The practical rule is clear: keep the unidentified cylinder out of normal use and contact the owner or supplier.
Colour, valve type and cylinder shape may provide clues during a competent investigation, but they are not substitutes for positive product identification.
How gas cylinder identification relates to storage
Identification and storage are closely connected, but they are separate subjects.
Once the gas is correctly identified, its properties determine the controls needed for storage and handling. An inert gas, an oxidising gas and a flammable gas do not present the same hazards.
Northline’s Gas Cylinder Storage guide covers storage requirements separately.
A sensible site process is to identify the product first, understand its properties, and then apply the appropriate storage and handling controls.
Keeping the two subjects on separate pages also avoids repeating the detailed storage guidance already covered elsewhere on Northline.
What should industrial buyers check when receiving cylinders?
A consistent gas cylinder identification check at goods-in can help prevent the wrong product from reaching the point of use.
Check that:
- the gas or mixture matches the purchase order
- the product label is present and readable
- the ordered grade, purity or mixture specification is correct
- the UN number and danger information are consistent with the expected product
- important permanent markings are not obscured
- the cylinder is not being accepted only because its colour looks familiar
- any cylinder with uncertain identification is separated from normal use and referred back to the supplier.
These checks are particularly useful for multi-site operations and businesses sourcing gas from more than one supplier.
Frequently asked questions about gas cylinder identification
Can you identify a gas cylinder by colour?
Not reliably. The product label is the primary and mandatory means of identifying the contents. Shoulder colour is a secondary visual aid and should support, not replace, the written identification.
What colour is an oxygen cylinder in the UK?
For cylinders within the relevant system, oxygen uses a white shoulder, RAL 9010. Always confirm the product label before use.
What colour is a nitrogen cylinder?
Nitrogen uses a black shoulder, RAL 9005, under current UK guidance. The whole cylinder body does not have to be black.
What colour is an argon cylinder?
Argon uses a dark green shoulder, RAL 6001. Confirm the product from the label before connection or use.
What colour is a carbon dioxide cylinder?
Carbon dioxide uses a grey shoulder, RAL 7037. The cylinder body can follow a different owner or supplier colour scheme.
What colour is a helium cylinder?
Helium uses a brown shoulder, RAL 8008. The colour supports recognition, but the product label remains the primary reference.
Are industrial gas cylinder body colours standardised?
Usually not. BCGA identifies specific body-colour arrangements for acetylene, medicinal-gas cylinders and hydrogen. For most other cylinders, body colour can vary according to the cylinder owner or gas company within the applicable rules.
Does BS EN 1089-3 cover LPG cylinders?
No. LPG is outside the scope of BS EN 1089-3. Refrigerant-gas cylinders and the specified fire-extinguisher applications are also excluded.
What should I do with an unidentified gas cylinder?
Do not use it or identify it from colour alone. Keep it out of normal use and contact the cylinder owner or supplier so that the contents can be positively identified.
Correct gas cylinder identification starts with the label
Colour coding makes cylinder recognition quicker, particularly in workplaces where several industrial gases are in use.
It should never replace the written product information.
A reliable gas cylinder identification process starts with the label. Confirm the gas or mixture, review the relevant hazard and transport information, check the permanent markings, and use shoulder colour as secondary confirmation.
That method is more dependable for businesses receiving cylinders from different suppliers or operating across several European markets.
Northline Distribution supports professional industrial and technical gas requirements across European markets. Businesses reviewing gas specifications, cylinder formats or ongoing supply requirements can request a B2B gas supply quote.