LPG siting: low spaces and ventilation

LPG vapour is denser than air and can accumulate in low openings or concealed spaces, potentially reaching ignition away from the release. Its actual path also depends on airflow and mixing. Assess the full site before placing the cylinders.

Cylinder position

For propane cylinders in use supplying fixed appliances, the supplier’s siting guidance calls for a position that is:

• outdoors, open and well ventilated to reduce vapour accumulation
• upright on a firm, level base
• at least 2 m from un-trapped drains, gullies and cellar openings
• at least 1 m horizontally from ignition sources and from openings such as doors and windows

These are the cited supplier’s cylinder-in-use clearances, not a general distance rule for every store or bulk tank. Check the requirements for the actual arrangement. Separation reduces the risk of gas entering an opening or reaching ignition; it does not make a leak outdoors harmless. A gully or cellar light well beside a cylinder provides an unsafe accumulation route.

Enclosures and lockers

• A sealed cupboard is unsuitable: a leak cannot disperse, and the valves may be hard to reach in an emergency.
• A ventilated enclosure relies on its low-level openings. Keep them clear: clear upper openings do not make up for blocked low ones.
• In a touring caravan, the cylinder locker’s separation from the living space and low external openings provide a route away from the interior. Keep those openings clear and maintain the specified securing and separation. A locker does not remove the need to act on a suspected leak.

The appliance is a separate check

Well-sited cylinders do not settle where the appliance can go: an indoor boiler still needs its own air supply, flue and clearance checks.

• Combustion air and escape dispersal are different checks. A combustion-air vent does not mean every LPG escape will disperse.
• Covering the low-level vent of an open-flued LPG heater starves combustion and risks spillage and carbon monoxide. The vent must be restored.
• After converting from natural gas, check ventilation against the converted appliance's LPG instructions. Gas density does not set a vent's size or height.
• A flueless LPG heater takes air from its room and releases combustion products there. Check the model's minimum room volume and ventilation, as well as its oxygen-depletion cut-out. The cut-out stops the gas if oxygen falls to its trip point; it does not make an undersized or poorly ventilated room suitable. Choose another location or appliance if the siting requirements cannot be met.

Below ground

GSIUR regulation 6(8) restricts LPG appliances with automatic ignition or a pilot in cellars and basements, and bans gas storage vessels there. For LPG pipework, cellars, basements and unventilated suspended floors all count as voids, which must be adequately ventilated (regulation 19(6)). Under IGEM/G/11, a room below ground on one side but open to outside ground level on another can meet the ground-level condition; every other requirement still applies. For a basement below ground on every side, a window into a sunken light well, an alarm or a promise to keep a window open changes nothing: decline the installation and explain why. Never store cylinders below ground.

Detectors and pipe entry

• Fit an LPG detector low on an open wall, within the model's limits for height, distance and airflow. Do not put it in a cupboard or behind furniture, or copy a natural-gas detector or CO alarm position.
• Follow the service-pipe entry requirements, including above-ground entry and appropriate sleeving, sealing and protection. These measures reduce the risk of gas tracking into the building; check their actual condition: do not assume an entry is safe.

Suspected escape

Get people clear, prevent ignition and contact the LPG supplier's emergency service from a safe place. Close an external ECV and the cylinder valves only if you can reach them safely. Use no electrical switches or flames, and do not restore the gas until it is safe. Call 999 for a fire.