Gas (CH4) incident

Purpose

This procedure describes the actions to be taken by staff called to a premises following the activation of a gas alarm for natural gas (CH4), butane (C3H10) or propane (C3H8) or where there are other grounds to believe that fuel gases might be involved.

Responsibility

All Staff

Process

Although these gases may be poisonous (cause suffocation) in high concentrations, the greatest risk posed by these gasses is that the concentration rises to a level that would form an explosive mixture. Such an explosive mixture could be ignited by the smallest spark. Commercial gas alarms operate at concentrations well below those required for an explosion, typically 30% of explosive mixture or less.

When a gas sensor activates and alerts the contact centre they must call the London Fire Brigade and Transco to attend.

If staff are called to a property and discover a gas leak or smell gas they should ensure that no lights or electrical appliances are switched on or off. They must then from a safe distance outside the property phone the Fire Brigade and Transco.

If staff arrive in the dark and no lights are lit within the premises, they will need to use a torch and should switch the torch on before entering an area in which they can smell gas and, in any event, before opening the door to the premises.

They should only enter the premises if they both assess that it is safe to do so. On entering, they should ensure that the front door is secured open to ventilate the property.

Where staff judge it too dangerous to enter the premises, they should:

• Locate the gas shut off valve, if possible, and turn it to the off position.
• From a safe distance outside the property phone the Fire Brigade and Transco.
• Staff should try to ascertain who is in the premises and where they are.

If there is a strong smell of gas and staff are already inside the property, all occupants should be asked to leave immediately and provided with assistance, where necessary. Open any windows that they pass to enable any gas accumulation to be dispersed.