Heavy duty cooking appliances, such as charcoal ovens, charbroilers or gas woks etc have always been challenging for the fire safety. They are characterized by high heat loads that generate high temperatures inside the exhaust ductwork.
They also generate a large quantity of FOG (Fat, Oils and Grease) in addition to carbon particles. Using solid fuels, such as charcoal, adds another risk: they emit a significant amount of sparks. The fire risk is a considerable concern for heavy-duty cooking appliances, whatever its type.
A – Capture Jets
B – High heat, smoke and grease load
C – Cold water mist nozzles
D – KSA cyclonic filters
E – Water drain
Cold Mist technology is based on the use of a continuous, full-length fine Cold Water Mist inside the exhaust plenum of the hood. The heat and the airborne particulate (grease, oil, smoke, etc.) released by the cooking process passes through this mist. The air temperature is significantly decreased to a reasonable level. Some of the particulate matter is removed directly from the airstream, and the remainder becomes viscous. This causes the grease particles to join together and, as larger cluster, increase the efficiency of the KSA multi-cyclonic filters capturing them. Cold Mist technology has proven to be extremely efficient at removing FOG (fats, oils and grease) from the airstream, also reducing odour emissions at the point of discharge, which benefit the neighbouring premises.
Solid fuel and particularly wood, emit creosote and tar when burning. Both are also captured by the Cold Mist and KSA filters. As the exhaust air cools inside the duct, the remainder condenses out and coat the inner surfaces of the duct. It only takes the slightest spark to ignite these deposits. A major duct fire could be ignited without the Cold Mist, which also acts as an effective “Spark Arrestor”.
A – Hot water wash nozzles
B – KSA cyclonic filters
C – Hood water drain
At the end of the cooking period, a wash cycle thoroughly cleans the inside of the exhaust plenums. Maintenance is then reduced to the strict minimum as only the external surfaces of the hoods have to be cleaned.
Water has become an increasingly precious resource, and it is desirable to optimise its use. Halton has developed an intelligent technology that activates the cold Mist On Demand (MOD) only when it is strictly required and not on a continuous cycle.
Also used for M.A.R.V.EL. technology, Halton’s IRIS sensors scan the surface of the cooking appliances to determine its status and activate the Cold Mist accordingly. For charcoal ovens, for example, the Cold Mist is activated every time the oven door is opened. It stops after the door has been closed.
This is a safe and responsible approach that saves up to 80% on the water consumption of the Cold Mist.
The University College of food, Birmingham (UCB) has a large number of Cold Mist / Hot Wash hoods installed that are currently under a Halton service & maintenance agreement. UCB have key environmental targets that must be met every year to reduce the environmental impact of the site and by doing so secure core funding. They were keen to evaluate the potential savings the MOD technology could provide and agreed to a 1 month trial in 1 section of cold mist hood. Two adjacent sections of hood were then selected, each covering the same cooking equipment and both connected to pipework in the same way.