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Duct cleaning - gas safety
Carbon monoxide is the hazard you cannot see, smell or taste - a poisonous gas produced when gas appliances do not burn cleanly, which in a commercial kitchen full of gas equipment is a real and potentially deadly risk. Controlling it depends heavily on ventilation working properly. Here is the carbon monoxide risk in commercial kitchens explained, and how it is controlled.
The short answer
Carbon monoxide (CO) is a colourless, odourless, tasteless poisonous gas produced by the incomplete combustion of gas fuels - and a commercial kitchen full of gas appliances is a place it can be produced, particularly if appliances are faulty or the ventilation is inadequate. It is dangerous precisely because it cannot be detected by the senses: people can be poisoned without knowing, with symptoms from headaches and dizziness to unconsciousness and death. Controlling the risk depends on combustion being clean and the products of combustion being removed - which depends on the ventilation working properly. The key control in a modern commercial kitchen is a gas interlock system, which links the gas supply to the ventilation so that gas only flows to the appliances while the extraction and make-up air are running - stopping the gas if the ventilation fails, so appliances cannot burn without their products being extracted. Air-quality monitoring can add a further layer, warning and isolating the gas if levels rise. So the CO risk is controlled by clean combustion, working ventilation, and the interlock that ties them together - which is why the ventilation working properly is a safety matter, not just a comfort one.
What carbon monoxide is
Carbon monoxide is a poisonous gas produced by the incomplete combustion of carbon-based fuels, including the gas that many commercial kitchen appliances burn. When gas burns completely, it produces mostly harmless products; but when it burns incompletely - through a faulty appliance, a poor air supply for combustion, or a badly maintained burner - it produces carbon monoxide. So CO is a product of gas not burning cleanly, and a commercial kitchen, full of gas appliances in constant use, is a place where incomplete combustion, and so CO, can occur if things are not right.
What makes carbon monoxide so dangerous is that it is undetectable by the human senses: it is colourless, odourless and tasteless, so there is nothing to warn a person it is present. Unlike a gas leak, which is given a smell so it can be detected, or smoke, which is visible, carbon monoxide gives no sensory warning at all - people can be exposed to dangerous, even fatal, levels without any awareness that anything is wrong. This is why it is often called the silent killer. The symptoms of CO poisoning - headaches, dizziness, nausea, confusion, and at higher levels unconsciousness and death - can themselves be mistaken for other things, adding to the danger. So CO is a hazard defined by being invisible to the senses, which is exactly what makes controlling it, and detecting it by other means, so important. You cannot rely on noticing it; you have to prevent it and detect it deliberately.
Why kitchens are at risk
A commercial kitchen is a place of particular CO risk because it has many gas appliances burning constantly, and CO is produced when that gas does not burn cleanly. The risk rises with faulty or poorly maintained appliances - a burner that is not burning properly, an appliance in poor condition - which are more likely to combust incompletely and produce CO. So keeping the gas appliances properly maintained and in good working order is a first line of defence: well-maintained appliances burning cleanly produce little CO, while faulty ones can produce dangerous amounts.
But appliance condition is not the only factor - the air supply for combustion matters too. Gas appliances need enough fresh air to burn cleanly; if the air supply is inadequate, combustion can become incomplete and produce more CO, even in an otherwise sound appliance. This links the CO risk directly to the ventilation: the ventilation has to supply enough fresh air for clean combustion and remove the products of combustion. If the ventilation is inadequate - not enough make-up air, or extraction not working - combustion can suffer and CO can build up. So a commercial kitchen's CO risk depends on both the appliances burning cleanly and the ventilation working to supply combustion air and remove the products. This is why CO safety in a kitchen is tied to the ventilation working properly - a point that makes the extraction and its performance a safety matter, not just a matter of clearing smells and heat.
The gas interlock
The key engineering control for CO risk in a modern commercial kitchen is a gas interlock system, which ties the gas supply to the ventilation so that the two cannot be dangerously mismatched. The interlock works on a simple, powerful principle: gas only flows to the appliances while the ventilation - the extraction and the make-up air - is running properly. If the ventilation is not running, or fails, the interlock shuts off the gas supply, so the appliances cannot burn. This ensures that gas appliances can only operate when there is ventilation to supply combustion air and remove the products of combustion - preventing the dangerous situation of appliances burning without adequate ventilation, which is when CO can build up.
This is now the minimum standard for new commercial kitchen installations, precisely because it directly addresses the core CO danger: gas burning without the ventilation to handle it. With an interlock, the ventilation working is a precondition for the gas flowing - so the ventilation cannot fail while the appliances keep burning, because the interlock stops the gas if the ventilation stops. It is a safety mechanism that makes the two systems interdependent in the right way. Some systems add air-quality monitoring for a further layer - sensors that give a pre-alarm if air quality deteriorates (for instance at a raised carbon dioxide level, which can indicate combustion issues) and isolate the gas if it worsens further, adding detection to the interlock's prevention. So the gas interlock, possibly with monitoring, is the central control: it makes working ventilation a condition of the gas flowing, which is exactly the protection the CO risk needs. It is the reason a modern gas kitchen is much safer than one where gas could burn regardless of the ventilation.
Why ventilation performance matters
The connection between CO risk and ventilation has an important implication: the ventilation working properly is a safety matter in a gas kitchen, not just a matter of comfort. In a kitchen without gas, ventilation performance is mainly about clearing heat, smells and grease - important, but not directly a life-safety issue. In a gas kitchen, the ventilation is part of the CO safety: it supplies the combustion air and removes the products of combustion, and via the interlock it governs whether the gas can flow at all. So a ventilation system that is under-performing - through a clogged, grease-laden extract, for instance - is not just failing to clear the air; it is compromising a system that has a role in gas safety.
This raises the stakes on keeping the ventilation performing in a gas kitchen. An extract that has clogged with grease and lost airflow is under-performing - and in a gas kitchen, that under-performance touches the CO safety, because the ventilation's job of removing combustion products and supporting the interlock depends on it working. A gas interlock, moreover, may respond to the ventilation not performing by shutting off the gas - which stops the kitchen working - so a poorly maintained, under-performing ventilation system can even interrupt the kitchen's operation via the interlock. So keeping the ventilation clean and performing matters doubly in a gas kitchen: for the CO safety it supports, and to keep the interlock from cutting the gas. This is a strong reason, beyond the usual ones, to keep the extraction clean and working in a gas kitchen - the ventilation is part of the gas safety, and a clean, well-performing system is part of keeping the CO risk controlled.
The takeaway
Carbon monoxide is a colourless, odourless, tasteless poisonous gas produced by the incomplete combustion of gas fuels - and a commercial kitchen full of gas appliances is a place it can be produced, particularly if appliances are faulty or the ventilation is inadequate. It is dangerous precisely because the senses cannot detect it: people can be poisoned without knowing, with symptoms from headaches and dizziness to unconsciousness and death. So it has to be prevented and detected deliberately, not noticed. The risk depends on the appliances burning cleanly (so well-maintained appliances matter) and on the ventilation supplying combustion air and removing the products (so working ventilation matters).
The key control is a gas interlock, now the minimum for new installations, which links the gas supply to the ventilation so gas only flows while the extraction and make-up air are running - stopping the gas if the ventilation fails, so appliances cannot burn without their products being extracted. Air-quality monitoring can add a warning-and-isolation layer. Crucially, this means the ventilation working properly is a safety matter in a gas kitchen, not just comfort: an under-performing, clogged extract compromises a system with a role in gas safety, and can trip the interlock and cut the gas. So keeping the ventilation clean and performing matters doubly in a gas kitchen - which makes the extraction's maintenance part of controlling the CO risk, alongside clean-burning appliances and the interlock that ties gas to ventilation.
Questions
A colourless, odourless, tasteless poisonous gas produced by the incomplete combustion of gas fuels. It is dangerous because the senses cannot detect it - people can be poisoned without any warning, with symptoms from headaches and dizziness to unconsciousness and death, often mistaken for other things. This is why it is called the silent killer, and why it must be prevented and detected deliberately rather than noticed.
Because they have many gas appliances burning constantly, and CO is produced when gas does not burn cleanly. The risk rises with faulty or poorly maintained appliances that combust incompletely, and with an inadequate air supply for combustion - if the ventilation does not supply enough fresh air, combustion can suffer and produce more CO. So the risk depends on both the appliances and the ventilation.
The key control in a modern commercial kitchen - it links the gas supply to the ventilation so that gas only flows to the appliances while the extraction and make-up air are running. If the ventilation is not running or fails, the interlock shuts off the gas, so appliances cannot burn without ventilation to supply combustion air and remove the products. It is now the minimum standard for new installations.
By making working ventilation a precondition for the gas flowing. This prevents the dangerous situation of gas appliances burning without adequate ventilation - which is when CO can build up - because the interlock stops the gas if the ventilation stops. Some systems add air-quality monitoring that gives a pre-alarm if levels rise and isolates the gas if they worsen, adding detection to the interlock's prevention.
Because in a gas kitchen the ventilation is part of the CO safety - it supplies the combustion air, removes the products of combustion, and via the interlock governs whether the gas can flow. So an under-performing ventilation system, such as a clogged grease-laden extract, is not just failing to clear the air; it is compromising a system with a role in gas safety. Ventilation working is a safety matter, not just comfort.
In a gas kitchen, a clean, well-performing extraction supports the ventilation's role in CO safety - removing combustion products and helping the system work with the interlock. An extract clogged with grease loses airflow and under-performs, compromising that safety role, and can even trip the interlock to cut the gas and stop the kitchen. So keeping the extraction clean matters doubly in a gas kitchen: for the CO safety and to keep the interlock from cutting the gas.
In a gas kitchen, the ventilation is part of the carbon monoxide safety - a clogged, under-performing extract compromises it. Our duct cleaning keeps the extraction working, supporting the gas safety it underpins.
