• An LPG OPSO valve is an automatic changeover regulator that connects to your gas bottles.

    OPSO stand for overpressure shut off.

    What is an LPG OPSO Valve?

    The OPSO safety device cuts off the gas flow in the event of an abnormal gas overpressure.

    This could be caused by a fault in the gas regulator deterioration of a part even, a defect in the installation, or even liquid LPG entering into the regulator itself.

    Introduction on how LPG Propane gas works

    The gas bottles, Valves, Regulators, LPG OPSO Valve, Hoses & Safety.

    Gas Safety Installation and Use Regulations 1998

    The safe installation, maintenance and use of gas fittings.

    Regulation 3 enables you to replace “certain like for like hose/regulator, such as used or worn items are replaced” without being Gas Safe registered.

     But, you must, be deemed competent before attempting any of these activities yourself.

    This also includes the following. The replacement of a hose or regulator on a portable or mobile space fire heater.

    The replacement of a gas hose connecting a refillable gas bottle to the installation pipework.

    The Anatomy of an LPG Gas bottle

    An LPG gas bottle is a pressure vessel made up of a 2 to 3mm mild steel plate and is of welded construction.

    The surface of a gas bottle in direct contact with the Liquefied Petroleum Gas is known as the wetted area.

    How gas bottle Works

    A ‘full’ gas bottle is not full of liquid gas, space is left for expansion of the liquid gas and a supply of compressed vapour in the space above the liquid level.

    The percentage fill varies with the size of the gas bottle but normally has a maximum fill of 80 to 87%.

    When the valve on the bottle is opened, gas is pushed out of the vessel by the pressure and as a result, the pressure above the liquid is reduced.

    The liquid takes in heat from the gas bottle and the outside atmosphere and begins to boil, giving off vapour.

    As the conversion of liquid to gas continues, the liquid level slowly falls.

    When the gas bottle valve is closed again the pressure inside will rebuild up to the vapour pressure of the liquid, irrespective of how much liquid is left in the container.

    Gas bottle Valves prevent the gas from escaping from the gas bottle.

    They contain a pressure relief device which activates if the pressure builds up in the gas bottle due to excessive heat.

    • – Butane 21 bar
    • – Propane 26 bar

    Gas Bottle Valves

    Butane Valves

    4.5kg Butane gas bottles have a hand wheel connection with a male left-hand thread valve.

    7kg, 12kg and 15kg cylinders are fitted with a 21mm clip-on self-sealing valve.

    Propane Valves

    3.9kg, 6kg, 13kg, 19kg and 47Kg Propane gas bottles are fitted with a handwheel which has a POL connection valve.

    The gas bottle valve has a female left-hand thread

    A regulator (LPG OPSO Valve)must be included in the connection between the gas bottle/s and the appliance, except for appliances designed to be supplied at the gas bottle or vapour pressure.

    The regulator is precisely set by the manufacturer to control the pressure of the gas supply and must not be adjusted.

    Regulators must be certified and marked with BS3016 (now withdrawn) or BSEN12864 for gas bottle mounted regulators or BSEN13786 for Automatic Changeover Devices (ACDs).


    Patio gas bottle Regulator – Propane regulator

    27mm Propane Regulatorperating pressure: 37mbar

    Reinforced diaphragm, Inlet, 27mm, Outlet, 8mm nozzle

    21mm Butane Regulator

    Operating pressure: 28mbar Reinforced diaphragm Inlet, 21mm Outlet, 8mm nozzle

    Clip-on Regulators

    Operating pressure: 37mbar, Reinforced diaphragm, Inlet, 27mm, Outlet: 8mm nozzle

    Screw on Regulators.

    Low-Pressure Butane Regulato Operating pressure: 28mbar Reinforced diaphragm Inlet union 109, Outlet: 8mm nozzle

    Low-Pressure Propane RegulatorOperating pressure 37mbar Reinforced diaphragm Inlet, POL 105, Outlet: 8mm nozzle

    Automatic Changeover Devices (ACDs)

    Low-Pressure Automatic Changeover Device

    • – Operating pressure: 37mbar
    • – Reinforced diaphragm
    • – Limited relief: 55mbar
    • – Over Pressure Shut Off (OPSO): 75mbar
    • – Inlet: union 105
    • – Outlet: 1/2 inch BSP Ball Valve
    • All regulators that are not connected directly to a cylinder i.e. those connected by a hose should be positioned above the top of the cylinder
    • LPG OPSO Valve?

    Hoses must be certified and marked either BS3212 or BSEN1763 and bear the year of manufacture and name of the manufacturer

    Gas Hose length should be as short as possible but should not be stretched.

    All hoses must be secured with proper hose clips.

    Ensure the hose is kept clear of hot spots.

    Hoses fitted to cabinet heaters must be marked BS3212 type 2, be BSEN1763 class 3 and be of 8mm inside diameter.

    Hoses for ACDs must be marked BS3212 type 2 be BSEN1763 class 3 and be of 8mm inside diameter. 

    These must be supplied as a complete assembly with end fittings, crimped to the hose.

    General gas bottle Information.

    Treat gas bottles with care to ensure that the valve does not get damaged.

    Always use gas bottles in the upright position unless specifically designed for liquid offtake. 

    Liquid offtake gas bottles that are used on their side are only found on Fork Lift Trucks.

    Be careful when manual handling gas bottles.

    They weigh approximately twice the net weight shown.

    Use mechanical aids or trolleys where appropriate.

    Don’t subject a gas bottle to heat as the pressure inside could build up to exceed the safe limit of the pressure relief valve.

    Don’t attempt to disconnect or unscrew a regulator from any gas bottle if the flame on an appliance does not go out when the regulator is switched off.

    Don’t store gas bottles in cellars.

    • – areas below ground level
    • – within 2 meters of untrapped drains, unsealed gullies or openings to cellars.

    Propane gas bottles must not be used indoors on domestic premises.

    Propane and Butane gas bottles must not be supplied for blocks of flats where a piped gas supply is prohibited.

    Most people do not realise how dangerous propane gas bottles are.

    The LPG Valve OPSO is all part of the safety side of gas. It prevents overpressure from the gas bottles, also regulating the gas flow to the appliances.

    As with all gas, it is recommended, to employ a registered LPG gas safe engineer

    They will test your LPG gas supply for leakage as well as check your appliances for safety.

    We hope this article has given you an insight into how the LPG OPSO Valve works as well as details of how the gas bottles work.