What to Do in a Natural Gas Leak at Work

What to do in a natural gas leak: the first minute

Natural gas is odourless; the sharp, sulphurous smell is added to the gas so that leaks can be noticed. This smell is a warning, and when gas is smelled at work, the decisions made in the first minute determine whether the event will be a minor fault or an explosion. The answer to the question of what to do in a natural gas leak is short: ventilate without making sparks, shut off the gas, clear the area, raise the alarm from outside.

This article explains what to do, and what never to do, when gas is smelled at work, where to place gas alarm detectors and how to mark the shut-off valves. Offices and shops heated by natural gas are within the scope of this article as much as businesses with boiler rooms, industrial kitchens, ovens or drying processes.

What never to do

A mixture of gas and air in a certain proportion can be ignited by a small spark. So in an area where a leak is suspected:

• Do not switch electrical switches on or off. Light switches, sockets, circuit breakers and doorbells can produce a spark at the moment of contact. Do not unplug an appliance that is running, and do not start one that is off.
• Do not talk on the phone inside. Calls are made after leaving the area where the gas is.
• Do not use lighters, matches or cigarettes; stop hot work such as welding, grinding and cutting immediately.
• Do not run electric fans or extractors. Ventilation is done naturally by opening doors and windows. Fixed ventilation systems installed as Ex-proof are assessed separately.
• Do not use lifts; stairs are used for evacuation.
• Do not stay in the area to look for the source of the gas. Finding the leak is the job of the distribution company’s emergency team.
• Do not turn the gas back on. No valve is opened and no appliance is put back into service until the emergency team gives approval.

Natural gas smell: the order of evacuation and raising the alarm

1. Stop and warn others. The person who notices the smell warns those around them verbally; if there is an alarm button and it is outside the area where the gas is, it is used.
2. Stop sparks and flame sources. Hot work is stopped; if they can be reached safely, burning appliances are shut off at their own valves.
3. Open doors and windows. Natural gas is lighter than air and rises; high-level windows and roof openings help.
4. Close the gas valve. If the leak is in a single appliance, the appliance valve is closed; if not, the section or main shut-off valve. If the valve is at a point where the gas is concentrated, nobody is sent in.
5. Clear the area. Employees go along escape routes to the assembly point; visitors and subcontractor employees are also counted.
6. Call from outside. The 187 Natural Gas Emergency line is called from outside the area where the gas is. If there is a fire, explosion or injury, 112 is also called.
7. Prevent entry. Nobody enters the building or area until the emergency team arrives; the team must be able to reach the building’s gas service box and valves easily.
8. Turning back on: The gas is turned on only after the emergency team has confirmed that the leak has been fixed and the area is safe; appliances are put back into service by an authorised service.

The sign of a gas leak is not only the smell; a hissing sound from a pipe or connection point and a warning from a gas alarm detector are dealt with in the same order. Carbon monoxide, a combustion product, is odourless and a different hazard; on this subject, see our article on carbon monoxide from heaters and stoves.

Gas alarm detectors: where are they mandatory, and where are they placed?

The Regulation on the Protection of Buildings from Fire makes gas detection mandatory in several articles:

• Art. 55/5: Where natural gas or LPG is used in a boiler room, gas detectors to detect these gases are mandatory.
• Art. 57/1: Excluding homes, in kitchens in shopping centres and high-rise buildings, food factories and kitchens serving more than 100 people at a time, a gas detection, gas shut-off and alarm installation suited to the properties of the gas used in the cookers is mandatory.
• Art. 112/ç: There is an emergency solenoid valve at the entrance to heating plants, and this valve is controlled by at least two explosion- and spark-proof, stepped gas sensors. In heating plants with large consumption, an integrated gas alarm device is also used.
• Art. 112/g: In any gas leak or combustion event, the gas flow is stopped automatically by the shut-off valve.

The location of the detector is chosen according to the weight of the gas relative to air:

The exact mounting distances are given in the device’s user manual and in the gas distribution company’s technical specification; the authorised company that has the project approved arranges the layout according to these requirements. On site, avoid these mistakes: placing the detector in front of a door or window, in the air flow of a ventilation grille or where steam from the cooker hits it directly; painting over or covering it; unplugging the device after a fault or false alarm and forgetting about it.

Detectors are tested and maintained at the intervals specified by the manufacturer; in addition, periodic inspection and maintenance of the building’s internal installation, gas shut-off devices, consuming appliances and flues are carried out by authorised services (Art. 112/ı). You can enter these dates in our OHS calendar tool.

Marking the shut-off valves

The question that wastes the most time in a gas leak is “where is the valve?” The Regulation on Emergencies in Workplaces requires electricity and gas cut-off points to be shown in the emergency plan. The Regulation on the Protection of Buildings from Fire also requires natural gas users to learn where the gas shut-off valves are (Art. 112/i), the building service box to be protected so that emergency teams can intervene easily, with no materials placed and no vehicles parked in front of it (Art. 112/h), and warning signs to be posted in areas where natural gas is used (Art. 112/f).

In practice, marking is done as follows:

The number of each valve must be the same on the evacuation plan and in the list in the emergency plan. The plan is posted at entrances and on each floor. The authority and sequence for closing valves is written by name in the support staff’s task list; someone is also designated to take on this task on the night shift. For the colours and shapes of signs, see our article on health and safety signs.

Drills and training

A gas leak scenario is a suitable and realistic scenario for the emergency drills held at least once a year. Points to measure in the drill:

• Whether the person who notices the smell informs the right person and does not touch electrical switches
• Whether the section valve is closed by the right person, and how long it takes
• Whether the power is cut from a point where there is no gas
• How long evacuation and the headcount take to complete
• Whether 187 is called from outside the area where the gas is, and whether the point where the emergency team will be met is clear

For writing the scenario and the drill form, see our article on emergency drills. Checking the gas installation after events such as earthquakes is also part of the plan; this subject is covered in our article on returning to the factory after an earthquake. For areas where natural gas is used in processes and explosive atmospheres may form, an explosion protection document is prepared separately.

In businesses in Bursa and the surrounding provinces, we incorporate the gas leak scenario into the plan, the evacuation plan drawing and the drill programme as part of our emergency plan service. For food businesses with large kitchens and factories with canteens, checking the kitchen gas detection and shut-off arrangement is also part of this work.

Frequently Asked Questions

What should be done first in a natural gas leak?

Without touching electrical switches or making sparks, doors and windows are opened, the gas valve is closed if it can be reached safely, the area is evacuated and the 187 Natural Gas Emergency line is called from outside the area where the gas is.

Should the electricity be cut off in a gas leak?

Circuit breakers or switches in the area where the gas is are not touched, because a spark can occur at the moment of contact. If the power needs to be cut, this is done from the main panel at a point where there is no gas. Boiler rooms must have an external cut-off installation for this purpose.

Where should a gas alarm detector be fitted?

Since natural gas is lighter than air, it is fitted near the ceiling; since LPG is heavy, near the floor. The exact distances are given in the device’s manual and the gas distribution company’s technical specification; the detector is not placed in front of doors, windows or ventilation grilles.

Is a gas alarm detector mandatory at work?

A gas detection and shut-off installation is mandatory in boiler rooms using natural gas or LPG and in the large kitchens listed in the regulation. In other areas, whether it is needed is determined through the risk assessment and emergency plan work.