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Gas Interlock System FAQs

Gas Interlock SystemA gas interlock system is often referred to as a gas safety interlock system. This is a device providing a failsafe ensuring safety and decreasing the risk of accidents in commercial kitchens. The flow of gas is restricted by the gas interlock system to all appliances when the ventilation system is not performing correctly. Once the issue is corrected, the normal flow of gas is resumed.

This is how the gas interlock system prevents nitrogen dioxide and carbon monoxide from building up. This is a significant threat to the health of the employees. The design of the interlock system also prevents explosions resulting when unburned gas builds up. The airflow of the gas interlock system is monitored through a built-in sensor.

When there is insufficient airflow or none at all, the flow of gas will stay shut off. Once the supply of gas is cut off, the airflow must improve prior to the kitchen equipment being used.

Which Businesses Need a Gas Interlock System?

Every business that has an operational commercial kitchen with gas powered equipment is required to have a gas interlock system. The system must be fitted in accordance with the Gas Safe Regulations and the British Standard BS6173. If a business does not have a gas interlock system, potential repercussions include:

  • The commercial kitchen can be closed until the installation of safety systems
  • The business may fail the gas safety inspection
  • Unacceptable safety and health risks for the general public and the employees
  • The financial future of the company may be threatened due to additional fines
  • The Health and Safety Executive can prosecute the business

For all of these reasons, any business with an operational commercial kitchen must ensure the fitting of a gas interlock system.

Who Can Perform Work on a Gas Interlock System?

Only Gas Safe registered engineers can repair or install a gas interlock system. The regulations of the Gas Safe must be met by the engineers. It is illegal for all individuals not registered with Gas Safe to perform work on any of these systems. It is important to make certain all sub-contractors hired for the maintenance of a gas interlock system have the proper qualifications.

The Legalities of the Gas Interlock System

According to the British Standard BS6173 and the gas safety regulations of the United Kingdom, any food business with an operational commercial kitchen is required to have a gas safety interlock system installed. This means in order for the business to be compliant with the law, a gas safety interlock system is mandatory.

The Way the Interlock System Works

Every gas interlock system has one or more fans within the extraction system. The system monitors the fan’s operation. There are two different ways this can be achieved. The first is a differential air pressure switch. This can sense the static air pressure. There are different levels of sensitivity the pressure switch can be set to. This will shut off the air when the level of sensitivity is reached.

The second option is an electrical current sensor. This can be used as opposed to an air pressure switch. The same objective is achieved because the electrical current to the fan is being monitored.

The Maintenence for a Gas Interlock System

Routine and regular maintenance is required for gas interlock systems. This makes certain the system is functioning properly according to the standards of the BS6173. If the system is not maintained correctly, the result may be problems that prevent the commercial kitchen from functioning properly. A routine check must be performed for the gas interlock system. This ensures the system is performing as specified.

All gas safety devices must be checked a minimum of once per year. This provides verification the gas cut off and airflow detection are working as expected. Every operating component within the gas interlocking system needs to be checked by a qualified engineer. This ensures everything is working efficiently including the pipework, gas hoses, sensors and valves.

The Importance of the CP42 Certificate

A non-domestic Commercial Gas Safety Inspection CP42 certificate is what the safety certificate is officially called. An engineer registered with Gas Safe issues this certificate annually. This encompasses all of the appliances and installation in commercial kitchens. This generally includes all pipework, interlock and extraction systems and gas appliances.

Commercial kitchen facilities are specifically targeted by this certificate. The regulations include:

  • Take-away shops
  • Food production centres
  • Catering businesses
  • Cafes and restaurants
  • Staff canteens

Businesses Requiring a Current CP42 Gas Safety Certificate

All businesses with a commercial kitchen operating gas appliances require this certificate. The business is legally obligated to make certain all gas equipment in use by the business is certified and checked a minimum of once per year by an engineer certified as qualified by Gas Safe. The business insurance coverage is dependent on having a current safety certificate.

If the property is leased, the assumption should not be made the landlord is now the responsible party. There are clauses in the majority of leases passing the gas safety responsibility to the leaseholder.

What is Required for the Connection of a Gas Interlock System?

The gas interlock system must be connected to the gas solenoid valve. This is sold separately. The configuration must shut off the main gas supply when the extraction air is insufficient or the fan will not run. Only a certified engineer can legally install a gas interlock system. When the installation of a gas interlock system is required for a commercial kitchen, only a qualified individual or company should be contacted.

The company will recommend the best installation and design for the ventilation system. The business will be offered the best solution for their specific needs. It is important to note some gas interlock systems are more economical to use than others. The actual cost is dependent on the system being installed.

The Risk of Non-compliance with the Regulations

  • Trade can be negatively impacted when an Immediately Dangerous or At Risk certificate is issued by an installer registered with CORGI.
  • The health of the employees is placed at risk.
  • If there is a reason for an HSE incident investigation, the business may be referred to Crown Court and receive a maximum of a ¬£5,000.00 fine.
  • An individual or employee can make a claim against the business due to a related accident.

When a Gas Proving System is Necessary

Potentially dangerous situations are prevented with a gas proving system. This is accomplished by stopping the supply of gas from being turned on unless all of the isolation valves on the appliances have been closed.

Businesses Requiring a Gas Proving System

A gas proving system is required for all commercial kitchens without flame supervision. When the gas is turned on with an open isolation valve, all of the gas will vent directly into the kitchen. Dangerous situations are prevented from occurring because all isolation valves must be closed prior to turning on the gas supply.

The Importance of Flame Supervision

The flame supervision device is fitted directly to the gas appliance. When the flame goes out, the gas will be automatically turned off.

Check Your Gas Hoses

Gas hose products used in commercial kitchens are subject to Gas Safety (Installation and Use) Regulations. A gas hose requires a CE marking, CE markings are an indication that the gas hose conforms with the current regulations.

Caterhose Gas Hose Assemblies - Bayonet FittingCaterhose Gas Hose Assemblies – Bayonet Fitting

Die-Pat Caterhose gas assemblies with bayonet fitting are available in: 1000mm x 1/2″ BF, 1500mm x 1/2″ BF and 2000mm x 1/2″ BF


Gas Hoses with Bayonet Finning


Caterhose Gas Hose Assemblies - Braided RangeCaterhose Gas Hose Assemblies – Braided Range

Die-Pat Caterhose braided gas hoses, available in 1000mm x 1/2″QC, 1500mm x 1/2″QC, 2000mm x 1/2″QC, 1000 x 3/4″QC and 1500mm x 3/4″QC.


Braided Gas Hoses


Caterhose Gas Hose Assemblies - Standard RangeCaterhose Gas Hose Assemblies – Braided Range

Die-Pat Caterhose gas hose assemblies standard range are available in the following sizes: 1/2″QC lengths of 1000mm, 1250mm, 1500mm and 2000mm 3/4″QC


Standard Gas Hoses




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