Gas Safety

Connecting Safely

Connecting cylinders and equipment safely is vital.

Valve operation

open cylinder valves slowly using the correct spindle key or the handwheel fitted on some cylinders
soft seat, spindle key operated cylinder valves should not be subjected to excessive torque
an opened valve should never be left against the backstop but should be turned back half a turn to avoid seizure in an open position
to shut the valve turn it clockwise just enough to stop the gas completely - never use force
if you stop work for more than a few moments, close the cylinder valve

Inflammable gas cylinder valve spindles have right-hand threads, flammable gas cylinder valves have a left hand thread

Please note: spindle keys are obtainable from BOC retail stores.

Acetylene cylinders

If an acetylene cylinder has been transported horizontally, it should be placed in an upright position for a minimum of 12 hours prior to use.

Non-standard keys

To avoid damaging the valve seat or spindle square:

never use anything but the recommended cylinder valve keys
never increase the leverage of keys or use longer ones
never use spanners with long handles; or even the correct key if it is badly worn

If the valve spindle is too stiff to open by hand with the spindle key, return the cylinder to the supplier.

Broken spindles

If you think your cylinder valve has a broken or damaged spindle, do not try to use it.

Do not attempt to remove the gland nut as the broken spindle could be ejected or unwound at great risk to the operator

Contact BOC Gases Directline: 0800 111 333.

Gas pressure – correct equipment

The gas cylinder and outlet valve are designed to supply gas through an approved pressure regulator.

The pressure regulator screws directly into the valve outlet.

never install additional piping or fittings between regulators and the outlet valves of MCPs
when individual cylinders of the same gas are manifolded together to a common outlet, the pressure regulator should be screwed into this outlet
use needle or fine adjustment valves downstream of the pressure regulator only, never upstream

Pressure regulators

the pressure regulator must correspond to the pressure in the cylinder
the threads must be the same as the valve outlet
never force any connection
regulators should be maintained regularly in accordance with the manufacturer's instructions
do not attempt to repair or modify the regulator

Fitting a pressure regulator

Before fitting a pressure regulator to a full cylinder always screw out the pressure adjusting screw to stop flow through the regulator when the cylinder valve is opened.

Pressure regulator connection

This advice applies to ALL gas cylinders and regulators:

never try to ease any regulator threads with oil
never use PTFE tape
never 'pack-out' a connection
never use any connection that appears worn when tightening or loose when fully screwed home

Correct regulator

Never interchange left-hand threaded pressure regulators between gases. They are designed for use with a specific gas and to interchange them could be hazardous.

Never use left-hand to right-hand adaptors.

Remember: cylinder pressure and properties are different for each gas.

Fit flashback arrestors

Flashback arrestors prevent flames travelling back into cylinders.

They should be fitted downstream of pressure regulators in oxygen, acetylene, propane and hydrogen systems.

Manifold - regulators and flashback arrestors

cylinders connected to a manifold or header system must be properly designed for the task and installed by a specialist engineer
it must be fitted with one or more pressure regulators
acetylene manifolds must also be fitted with a flashback arrestor

Use a non-return valve with mains gas

When using mains gas, the law states that a British Gas (BG) approved non-return valve must be fitted.

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