Gas escapes and emergency actions

A gas escape is the situation every gas engineer must be able to deal with, on site or over the phone. The priority is always the same: protect life and property first.

Why escaping gas is dangerous

Gas only burns or explodes when it is mixed with air in the right proportion. For natural gas, that range, its flammability limits, is 5% to 15% gas in air.

Natural gas is lighter than air. LPG is heavier than air, which is why the advice for LPG includes ventilating at low level.

Advice to give over the phone

If a customer reports a smell of gas or fumes when you are not on site, it must be reported to the gas emergency service. They have the training and equipment to attend escapes. Until they arrive, give the caller this advice:

1. Turn off the gas. For natural gas, turn it off at the meter. If the meter is in a cellar or basement that smells of gas, don't go in: get everyone out of the building instead. For LPG, turn off at the storage vessel and outside the building, at the meter, or at every cylinder valve, depending on the supply.
2. Put out all naked flames. No smoking and no striking matches.
3. Don't operate electrical switches or equipment. Even switching a light on or off can ignite escaping gas.
4. Open doors and windows to ventilate. For LPG, ventilate at low level too, for example by opening outside doors.
5. Call the gas emergency number with the address of the emergency and the caller's name, address and phone number. For natural gas in England, Scotland and Wales this is 0800 111 999.

Who does what

• The gas emergency service. On the network, gas transporters must run a 24-hour emergency service and the National Gas Emergency number, and must make safe every reported gas escape or report of fumes as soon as reasonably practicable. They make the installation safe, and leave further investigation to another competent engineer. These duties come from the Gas Safety (Management) Regulations, not GSIUR.
• For LPG and other gas not supplied from a network, regulation 37 of GSIUR applies. The supplier must stop the escape within 12 hours of being told. The responsible person must shut off the supply straight away if they know or suspect gas is escaping. If gas still escapes, or the smell persists, they must tell the supplier at once. Nobody may turn the supply back on, except to repair it, until the cause has been dealt with.

On site

If you smell gas on an installation, carry out a tightness test (see 6.5 Tracing and repairing escapes). Under the Unsafe Situations Procedure, an installation that fails a tightness test is Immediately Dangerous. So is one that passes but still smells of gas. In that case, call the Gas Emergency Contact Centre for natural gas, or the gas supplier for LPG.

A fire or explosion caused by a gas escape is also Immediately Dangerous, and must be reported to the Gas Emergency Contact Centre or the LPG supplier (see 14.6 on gas incidents).

Sources: IGEM/G/11 Ed. 2 Appendix 4phone advice IGEM/G/11 Ed. 2 Section 6 notereporting IGEM/G/11 Ed. 2 3.4emergency service IGEM/G/11 Ed. 2 Table 1situations 1.2, 1.3 GSIUR 1998 reg. 37LPG and other gases L56 (2018) paras 315–316scope of reg. 37 IGEM/UP/1B Ed. 4 1.3lighter than air CCN1 Issue 16 §2assessed

▸Tutor notes

• Role-play the phone call: one learner reports a smell of gas, another gives the advice in order. Then repeat it with the meter in a cellar that smells of gas.
• Ask why switching a light off is just as risky as switching it on.
• Ask why the phone advice for LPG adds ventilating at low level.
• CCN1 §2 assesses regulation 37(1)–(4). Make sure learners know it applies to LPG and other non-network gas, and that network natural gas is covered by the Gas Safety (Management) Regulations.