Phoenix Journal · Extraction
Running gas in a commercial kitchen brings legal duties you cannot delegate away. Here is the plain-English position on inspections, interlocks and the ventilation obligations that sit alongside them.
Gas safety & compliance
If your kitchen burns gas, the law does not treat it as an optional extra - it treats safe installation, ventilation and maintenance as a duty you are legally bound to meet.
Commercial catering sits under some of the most closely enforced safety rules in the country, and for good reason. A busy line runs open flame, high heat and a constant stream of grease-laden air, often for twelve hours a day. Get the gas side wrong and you are not looking at a fine alone - you are looking at carbon monoxide risk, gas leaks and ductwork fires. This piece sets out where you stand legally, in plain terms, and where your extraction and ventilation obligations tie directly into gas compliance.
The backbone is the Gas Safety (Installation and Use) Regulations 1998, usually shortened to GSIUR and enforced by the Health and Safety Executive. The regulations are supported by Approved Code of Practice L56, which carries special legal standing - if you are prosecuted and shown not to have followed it, you must prove you met the law some other way. In practice, that means the ACOP is the benchmark you will be measured against.
The headline duties are straightforward. All gas work - installation, service, repair or removal - must be carried out by an engineer on the Gas Safe Register who holds the correct commercial catering qualifications. Domestic tickets do not cover a commercial kitchen. Every gas appliance, along with its pipework, flue and ventilation, must be maintained in a safe condition, and the accepted standard is an inspection at least every twelve months. That annual check is documented on a commercial catering gas safety certificate, commonly called a CP42, which is the record you produce for insurers, environmental health and enforcement officers. Keep those certificates on file. In the event of an incident or a spot inspection, the absence of a current record is often the first thing an officer notes, and it colours how everything else is judged. A well-kept folder of service records, interlock commissioning sheets and cleaning reports is the cheapest insurance you can buy.
Sitting alongside GSIUR are the technical standards that spell out how to do the work. BS 6173:2020 governs the installation and maintenance of gas-fired catering appliances, while IGEM/UP/19 covers the design and application of interlock devices - the systems that link your gas supply to your ventilation. HSE guidance for the sector was historically set out in Catering Information Sheet 23 (CAIS23), and the technical detail now lives largely in IGEM/UP/19, developed with the Institution of Gas Engineers and Managers. These are not casual recommendations. They are the documents a competent engineer and an enforcing authority will both work from.
Responsibility does not sit with the engineer who last serviced the hobs. It sits with you as the employer, occupier or person in control of the premises. GSIUR places the maintenance duty squarely on the duty holder, which means the business operating the kitchen is the party that must ensure appliances, safety devices and interlocks are kept in working order and checked for calibration as the manufacturer specifies. If you lease your unit, the split of responsibility should be pinned down in writing, but the default position is that whoever runs the kitchen owns the risk. Failing to comply is a criminal matter, and penalties run from unlimited fines to imprisonment where a breach is serious enough.
The single rule that catches most operators out is the ventilation interlock. GSIUR requires that a gas catering appliance is not used unless the flueing and ventilation are adequate, and IGEM/UP/19 turns that principle into a mechanical safeguard. A gas interlock proves that your extraction is genuinely moving air - through an air pressure differential switch or fan current monitoring - before it will allow the gas solenoid valve to open. If a fan fails, the emergency stop is hit or the fire alarm triggers, the interlock closes the valve and the gas stops. No proven airflow, no gas.
For new installations, IGEM/UP/19 goes further and makes carbon dioxide monitoring the minimum standard, on top of airflow proving. The numbers below are the working thresholds a compliant system is set to.
A word of realism on detectors: a commercial kitchen is not a clean-air environment. Grease condensate in the air means CO₂ sensor heads foul over time and can drift out of accuracy, which is exactly why calibration on the manufacturer's schedule is a legal expectation rather than a nice-to-have. An interlock that has been bypassed, left uncalibrated or wired around during a busy service is a defeated safety device - and if it fails to isolate the gas, the consequences are the ones the law is written to prevent.
It is tempting to file duct cleaning under fire safety and gas servicing under gas safety, as if they were separate worlds. They are not. Your interlock depends on the extraction system doing its job, and an extraction system choked with grease does not move air the way it did when it was commissioned. Reduced airflow means combustion products and carbon dioxide are cleared more slowly, and it puts strain on the very fans your gas supply is proved against. In a worst case, a system that has been allowed to clog can still satisfy a pressure switch on paper while moving far less air than the appliances below it actually need - a compliance box ticked over a real-world hazard. That gap between what the paperwork says and what the kitchen is doing is precisely where problems hide.
There is a fire dimension too. HSE guidance for the sector identifies flambeing, flame-grilling and stir-frying as common sources of ductwork fires, where an ignition source meets a build-up of grease inside the canopy and duct. The recognised benchmark for controlling that risk is TR19 Grease, published by the Building Engineering Services Association, which sets out how internal ventilation surfaces should be cleaned and evidenced. Insurers increasingly ask for TR19 Grease records, and a gas appliance running under an ungoverned, grease-laden extract is the exact scenario that turns a routine service into an incident.
Getting the two disciplines to work together also pays off day to day. Appliances that are serviced on schedule and vented through a clean, free-flowing system burn more efficiently and waste less heat, which is worth bearing in mind if you are looking at reducing gas bills in a commercial kitchen. And if you are fitting out a new site or reworking an existing one, thinking about how you plan the kitchen layout around extraction and gas from the outset makes interlock design, access for cleaning and future servicing far simpler than retrofitting compliance later.
Questions
Yes. Under the Gas Safety (Installation and Use) Regulations 1998 you must keep gas appliances, pipework, flues and safety devices in a safe condition, and the accepted way to evidence that is an annual inspection by a Gas Safe registered engineer with commercial catering qualifications. This is recorded on a commercial catering gas safety certificate, usually called a CP42. Without a current record, you will struggle with insurers and enforcement officers alike.
A gas interlock links your gas supply to your ventilation, so gas will only flow once the extraction is proven to be moving air. IGEM/UP/19 sets out how these systems are designed, and for gas catering appliances used with mechanical ventilation an interlock is the recognised way to meet the GSIUR requirement that ventilation must be adequate before gas is used. If a fan fails or the emergency stop is triggered, the interlock shuts the gas valve automatically.
Your interlock relies on the extraction system genuinely moving air, and a duct clogged with grease moves far less than it did when commissioned. That slows the clearance of combustion products and carbon dioxide and raises the fire risk inside the ductwork. Cleaning to the TR19 Grease standard keeps airflow honest, which is why gas compliance and extraction hygiene are best treated as one duty rather than two.
Under IGEM/UP/19, carbon dioxide monitoring is the minimum standard for new installations alongside airflow proving. A compliant system gives a first-stage alarm at 2,800 ppm, warning staff to increase ventilation, and shuts the gas solenoid valve if levels reach 5,000 ppm. Because grease in the air fouls sensor heads over time, those detectors must be calibrated on the manufacturer's schedule to stay accurate.
Phoenix Duct Clean · by the numbers
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