How should medical gas cylinders be stored?

The rules below come from HTM 02-01 (2026) Part B, the NHS England guidance on medical gas pipeline systems and cylinders; other countries apply their own regulations.

The store

• Only medical gas cylinders; industrial and pathology cylinders go in a separate store.
• Separate, clearly identified bays and racking for full and empty cylinders, and separate areas for each gas, with a physical barrier only where a risk assessment calls for one.
• Large cylinders secured against falling and each cylinder secured in its rack; smaller cylinders stored horizontally on protected metal racks.
• Clean, dry and free from combustible and flammable material; no naked flames or ignition sources, and a no-smoking area.
• Away from heat sources such as steam pipes and hot, sunny positions.
• Locked, with a notice showing where the spare key is; the fire and rescue service is told where the stores and emergency keys are.
• The main store on the ground floor, with external access for deliveries and returns.

How many cylinders to keep, and where

• Avoid stockpiling: volumes are set by risk assessment and stores are audited every six months.
• Satellite stores in departments such as theatres, emergency and coronary care: normally a 24-hour supply, or 48 hours for gas mixtures.
• Empty cylinders go back to the main store daily, and local stores should not keep them for more than 24 hours.
• Manifold rooms are not general stores: only the cylinders connected to the manifold plus enough to replace one complete bank, or two banks for oxygen/nitrous oxide mixtures where a risk assessment supports it.
• Small sites without a dedicated cylinder store, typically with fewer than ten cylinders, may keep small cylinders in the manifold room if they are segregated and a risk assessment validates it.

Oxygen/nitrous oxide mixtures

Ventilated stores may be cold, and at low temperature an oxygen/nitrous oxide mixture can separate. HTM 02-01 asks for these cylinders to be kept above 10 °C for 24 hours before use.

Handling rules that affect storage

Only trained and certificated staff should handle cylinders. Cylinders and valves are kept free from oil and grease, valves are closed after use and when the cylinder is empty, a labelling system shows the status of each cylinder, and leaking cylinders are removed from service and returned to the gas supplier.