Gas interlock systems
Gas interlock systems in commercial kitchens are part of the critical fire safety features in many buildings. For businesses in hospitality, care homes, education, offices, understanding gas interlocks is vital for both legal compliance and occupant safety. In this post, I will explain what gas interlocks are, how they work, regulations in the UK, risk implications, and how SPM Fire Safety Consultancy Limited can help you manage them.
What Is a Gas Interlock System?
A gas interlock system is a safety device designed to cut off the gas supply to appliances if the ventilation system fails or is insufficient. Basically, it prevents gas appliances (like ovens, boilers, or hobs) from working unless there is proven adequate airflow.
This is especially important in settings where gas appliances are used alongside mechanical ventilation (extract fans) – for example, in commercial kitchens, care homes or large offices with canteens.
How Does a Gas Interlock Work?
Here is a list of the key components and how they operate:
Ventilation / Extraction System – The extractor fans remove the fumes, heat, and products of combustion.
Pressure or Current Sensors – These sensors monitor whether airflow is above a safe threshold. Some systems use pressure differential switches, while others monitor fan current.
Control Panel – The interlock control panel receives data from the sensors. If airflow is sufficient, the panel will open the gas solenoid valve, allowing gas to flow to the appliances. If airflow falls below a safe threshold or it fails completely, then the valve closes and gas is cut off.
Gas Solenoid Valve – This is the valve that controls the gas supply. When the airflow, required pressure or fan current are met, the valve will open and gas will flow to the appliances.
Emergency Shut-off & Integration – Interlock systems often have an emergency stop (local or remote) which can also be connected to the fire alarm or building management systems (BMS). So, if the fire alarm activates, the interlock will shut off the gas supply to the kitchen appliances.
What does all this mean? – In practice this means that the extraction system is required to be operating, allowing the gas to flow, before any gas appliances are operated.
Why Gas Interlocks Are Required: Regulations & Standards
Gas interlock systems are not just best practice — in many cases, they are legally required:
Under BS 6173 (British Standard), interlocks are mandated since 2009 in new commercial kitchens or where there have been upgrades, to prove that ventilation is working before gas is supplied.
The IGEM/UP/19 standard (“Design and application of interlock devices … in commercial catering establishments”) provides rules for how interlock systems should be designed, including the type of proving (airflow, pressure, or current) required.
Guidance from building regulations also mandates interlocking for “Category B” gas-flued catering appliances: if mechanical extract is required for safe operation, the gas supply must be interlocked.
Additionally, there are important fire-safety interfaces: interlock systems often need to integrate with fire alarm or suppression systems to automatically shut off gas in a fire event.
Failure to comply can lead to serious consequences: risk to life, legal and insurance liabilities, or even fines.
What Is the Risk Without an Interlock?
Without a properly functioning or installed gas interlock:
Gas buildup: If ventilation fails but the gas keeps flowing, dangerous gases (e.g., carbon monoxide) can accumulate.
Explosion risk: Unchecked gas leaks can lead to fire or explosion.
Health risk: Toxic combustion products pose a threat to occupants and staff.
Regulatory non-compliance: In commercial settings, this could lead to failure in gas safety inspections, regulatory penalties, or insurance problems.
Operational disruption: If a gas interlock issue causes shut-off, gas appliances will stop, potentially shutting down key operations (like a hotel kitchen or a school canteen).
Sector-Specific Locations
In all types of buildings listed below, the installation, testing, maintenance and use of a gas interlock will assist to protect staff, visitors, residents and the building.
Hospitality
Gas interlocks are critical in commercial kitchens. In a restaurant, ventilation failure could shut down gas hobs, fryers, ovens — which impacts food prep and kitchen safety.
Retail and Offices
For shops that have a cafe or food prep area, interlocks are equally important to protect staff and customers, especially if gas appliances are used.
Office buildings may have canteens or commercial kitchen areas.
Medical settings/Care homes
The demographics of these buildings with vulnerable visiting or residential persons means that those premises with kitchens, the risk is magnified: persons may be exposed to toxic gases, and uninterrupted functioning of kitchens is vital for care.
Educational Buildings
School kitchens, college canteens, or university catering facilities are prime candidates. Gas interlocks help ensure student and staff safety and regulatory compliance.
Commercial
Any commercial premises (offices, workshops, pubs) that use gas appliances and mechanical ventilation should consider interlocks as part of their risk assessment.
Maintenance, Testing & Certification
To ensure ongoing safety, gas interlocks must be:
Installed by Gas Safe-registered engineers: Only qualified professionals should install and commission interlock panels.
Regularly serviced: Sensors, control panels, valves should be tested periodically to ensure they respond correctly.
Integrated with safety systems: Regular fire system tests should include the interlock’s interface (e.g., does gas shut off when the fire alarm goes off?)
Certified: In commercial kitchens, a CP42 certificate is often required. This certifies that the system (including the interlock) meets gas safety regulations.
Documented in risk assessments: When SPM Fire Safety Consultancy Limited assesses your building, I will note the presence, functionality, and maintenance status of gas interlocks, because they directly affect fire risk and gas safety.
What help can SPM Fire Safety Consultancy Limited offer
Identify – As part of the Fire Risk Assessment, I will observe and advise whether your kitchen has a gas interlock system installed.
Documentation & certification – If you do have one, then I will need to see evidence of testing and maintenance in the form of proper documentation. (e.g., maintenance logs, CP42 certificate) so you can demonstrate compliance to insurers, regulators, or auditors.
Inform – I will recommend if a gas interlock is required or should be installed as a consideration for “best practice” due to the demographics, location, open plan kitchen etc. of the assessed building.
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