LPG hoses: application and guidance

Gas Safe Register’s Technical Team provide guidance on LPG hoses and tubing and their uses.

This article appears in the November/December 2024 issue of Registered Gas Engineer magazine.

LPG hoses are used on a variety of installations to provide a flexible connection from cylinders and regulators. You can find examples of changeover valves mounted on upstands, residential park homes (RPH) and static holiday caravan connections, commercial mobile catering and transitioning to solid pipework, to name but a few.

When used downstream after a regulator, it is important that the hoses are sized correctly for the application to ensure that the gas supply is sufficient for the installation. Hoses should be of one continuous length but as short as practicable to allow for the flexibility that is needed. For static caravans/RPH connection, the hose should be a minimum of 300mm up to a maximum of 2 metres to allow for movement of the unit.

Environment
Hoses and tubing shall not be used where they could be subjected to ambient temperatures more than 50°C unless they have been designed specifically for that application/environment. Hoses should not pass through walls, floors or other voids.

By definition, a hose is of two-ply construction and designed to operate at higher pressures (BS EN 16436-1 Class 2 & 3/BS 3212 Type 2) whereas tubing is single-ply and designed to operate at lower pressures downstream of a regulating device (BS EN 16436-1 Class 1/BS 3212 type 1).

Note: Any installation or commercial activity covered by the Gas Safety (Installation & Use) Regulations 1998 within the scope of BS 6891 requires only hoses of Class 2 or 3 to be used.

Type
LPG hoses and tubing and assemblies shall conform to:
• Stainless steel flexible hose to BS EN 1SO 10380. For working pressure up to 2 bar, these hoses do not require protective braiding or reinforcement. For more than 2 bar, the hose requires an outer braiding.
• BS EN 16436-1 Class 1, a low-pressure application tubing (maximum pressure 0.2 bar/200 mbar) typically used downstream of a low-pressure regulator. These are not suitable for outdoor installations except where used to connect to a portable appliance such as patio heaters/BBQs, where, after risk assessment, a Class 1 hose with rodent protection may be more suitable for the application.
• BS EN 16436-1 Class 2, medium pressure (maximum 10 bar) hose used downstream of the regulator. It is recommended that these hoses are constructed with additional armoured protection.
• BS EN 16436-1 Class 3, high-pressure reinforced hose (maximum pressure 30 bar), commonly used where cylinders and hoses can be subjected to extreme summer temperatures. Typical use is a ‘pigtail’/direct cylinder pressure connection.

General guidance
Liquid Gas UK Code of Practice 33 sets out that all hoses and tubing used outside shall conform to BS EN 16436-1 Class 2 and 3 shall be armoured against rodent attack unless used for portable appliances.

Hoses installed directly to a cylinder and upstream of a regulator/changeover device shall be of a Class 3 type due to the higher operating pressures. If installed downstream of a regulator, a Class 2 hose should be sufficient.

Important: Hoses that provide rodent protection are not always the braided type. Certain brands have a rubber PVC outer layer and incorporate a metallic protection layer on the inside, which could provide adequate protection against rodent damage. If you are carrying out this type of work, you should consult with the manufacturer that they are of the correct type and suitable for the application required.

Hoses should be checked every time a cylinder is exchanged, and on any subsequent service/maintenance visits. Visual defects to check for include:
• Cracks
• Ruptures
• Blisters
• Stiffness
• Kinks/flattening
• General wear or damage.

If any visual defects are apparent, the hoses should be replaced immediately.

Markings
You may come across LPG hoses manufactured to other British Standards such as BS 3212. Hoses should be marked to represent the British Standard to which they conform and with information about what application they are designed for, and an expiry date or manufacturer date of hose.

Typically, a BS EN 16436-1 product should have BS number and date, class of hose with maximum working pressure, inside diameter of pipe, gas identification and an expiry date. These hoses should not be used after the expiry date and should be changed immediately.

For a hose conforming to BS 3212, this hose should show a date of manufacture. It is recommended that these are replaced after a maximum of 10 years of use. If this information is not present on the hose, you should risk-assess each installation and assess the physical condition and use of the hose.

Rubber tubing to BS EN 16436-1 Class 1 fitted to cabinet heaters should be replaced after five years of service. This type of LPG tubing shall normally display an expiry date of five years from manufacture for engineers to visually identify when replacement is required.

All equipment, including hoses, cylinders, valves and piping, shall be checked regularly for leakage and any visual defects.

More info on hoses is given in Liquid Gas UK Consumer Guidance Sheet 05 and Liquid Gas UK Code of Practice 33.

Bibliography
BS EN 16436 – Rubber and plastics hoses, tubing and assemblies for use with propane and butane and their mixture in the vapour phase
– Part 1 Rubber and plastics hoses, tubing and assemblies for use with propane and butane and their mixtures in the vapour phase. Hoses and tubings
– Part 2 Rubber and plastics hoses, tubing and assemblies for use with propane and butane and their mixture in the vapour phase. Assemblies
– BS EN 16436-1 Class 3, for direct cylinder pressure connections
– Liquid Gas UK CoP 33: Use of LPG Cylinders
– Liquid Gas UK Consumer Guidance Sheet 05: LPG Hose and Tubing for use with Vapour Offtake Cylinders
BS 3212:1991 – Specification for flexible rubber tubing, rubber hose and rubber hose assemblies for use in LPG vapour phase and LPG/air installations
BS 6891:2015+A1:2019 – Specification for the installation and maintenance of low-pressure gas installation pipework of up to 35 mm (R1 1/4) on premises
BS EN ISO 10380 – Pipework. Corrugated metal hoses and hose assemblies