Propane, butane, oxygen, acetylene, nitrogen, CO2 — most sites hold more than one gas, and each cylinder type brings its own hazards and its own storage rules. This guide explains the common gas cylinder types found on UK industrial sites, how to identify them, and what each one means for how — and where — you store it. For the law itself, see our separate guide to gas cylinder storage regulations.
Why cylinder type matters for storage
A compressed gas cylinder is hazardous twice over: the pressure in the cylinder, and the properties of the gas inside it. A leaking propane cylinder creates a flammable atmosphere; a leaking oxygen cylinder makes everything around it burn more fiercely; a leaking nitrogen cylinder can quietly displace the air in an enclosed room. The storage answer is different in each case, which is why identifying what you actually hold is step one of any cylinder storage plan.
The common gas cylinder types
LPG — propane and butane
The most common cylinders on commercial sites, fuelling heaters, forklift trucks, burners and catering equipment. Both are flammable liquefied gases stored under relatively low pressure; propane keeps working in cold weather where butane does not, which is why propane dominates outdoor and industrial use. LPG is heavier than air, so leaks pool at low level — a key reason LPG storage belongs outdoors in a ventilated cage, away from drains, pits and basements.
Oxygen
Used in gas welding and cutting sets alongside a fuel gas. Oxygen is not flammable itself but is a powerful oxidiser: it makes fires ignite more easily and burn harder. It must be kept away from oil and grease (which can ignite spontaneously in an oxygen-rich atmosphere) and segregated from flammable gas cylinders in storage.
Acetylene
The fuel gas in oxy-acetylene welding and cutting. Acetylene is exceptionally flammable and unstable under pressure, so it is supplied dissolved in a solvent inside a porous mass — and it has its own specific UK rules (the Acetylene Safety Regulations 2014). Acetylene cylinders should always be stored and used upright, secured, and well away from ignition sources.
Inert gases — nitrogen, argon and CO2
Nitrogen and argon cover purging, blanketing and welding-shield duties; CO2 serves welding, drinks dispense and refrigeration. None of them burn — the hazard is asphyxiation. Because they displace oxygen without warning, inert-gas cylinders should never be stored in small unventilated rooms; outdoor or well-ventilated caged storage is the safe default. Argon and CO2 are heavier than air and collect at low level.
Mixed and shielding gases
Argon/CO2 and other welding mixes behave as inert gases for storage purposes; treat any mix containing a flammable component (such as hydrogen mixes) as flammable.
Identifying cylinders: UK colour codes
UK cylinders follow the BS EN 1089-3 colour standard, which colours the cylinder shoulder by hazard and gas: maroon for acetylene, white for oxygen, black for nitrogen, dark green for argon, grey for CO2, and red or bright orange-red for flammable gases including propane (butane bottles are commonly blue). Treat colour as a guide only — the label on the cylinder is the definitive identification, and cylinders should never be accepted or stored without a legible label.
What each type means for your storage
Whatever the gas, the basics are the same: store cylinders upright, secured against falling, in a ventilated space — ideally outdoors — away from ignition sources, protected from vehicle impact, and behind a lock that keeps unauthorised hands off. Beyond that, the type drives three decisions:
Segregation. Keep oxidisers (oxygen) separated from fuel gases (LPG, acetylene) in storage, and keep full and empty cylinders apart so they can be found and handled correctly.
Location. LPG and other heavier-than-air gases should sit away from drains, gullies and basements; inert gases need ventilation that prevents an oxygen-deficient pocket forming.
Security and signage. Flammable gas storage should carry the appropriate warning signage and be lockable — both standard features of a purpose-built cylinder cage.
Matching the cylinder to the store
Our gas cylinder storage range is built by GPC in the UK around exactly these requirements:
Grenadier® gas cylinder cages — angle-iron cages designed to carry up to 16 'Calor gas' type cylinders, with hinged lockable doors and a highly-flammable warning sign supplied; mobile models add a push handle. A straightforward home for site LPG.
Grenadier® lock-up and knock-down cages — mesh-panel cylinder cages with lockable doors, retaining chains and galvanised roofs; knock-down models bolt together on site for easy access into your premises, with fixed or pallet-based options.
Cylinder pallet cages — fully welded transport cages with non-slip steel floors and retaining chains or straps, designed so cylinders can be moved safely by pallet truck or forklift rather than manhandled.
Walk-in gas cylinder stores — larger stores built with 90-minute fire-resistant panels in accordance with DIN 4102 and EN 13501, lockable, suitable for all gas types, with 12- or 24-mesh-door configurations for segregating cylinders.
For help choosing between cage formats, see the gas bottle cage buying guide; wider chemical and flammables storage lives in our hazardous storage range, and general secure compounds in storage cages.
Frequently asked questions
Can different gas types share one cage? Inert gases can generally share, but oxidisers and fuel gases should be segregated in storage — a walk-in store with separate mesh-door compartments, or separate cages, keeps this simple. Your DSEAR risk assessment should set the site-specific arrangement.
Do empty cylinders still need proper storage? Yes — an "empty" cylinder still contains gas at pressure and is treated as hazardous. Store empties in the same conditions as full cylinders, segregated and clearly identified.
Should gas cylinders be stored indoors or outdoors? Outdoors in a secure, ventilated cage is the default for flammable and inert gases alike; indoor storage needs specific ventilation and fire-resistance measures — this is where fire-rated walk-in stores come in.
How do I know what a cylinder contains if the colour is unfamiliar? Read the label — it is the legal identification. If a cylinder has no legible label, quarantine it and contact the gas supplier; never guess from colour alone.
This guide is general information, not site-specific safety advice — storage arrangements should follow your own DSEAR risk assessment and your gas supplier's guidance.