Kitchen Fire Protection Systems

Fires involving cooking materials, such as grease, fats and oils, have long been the cause of property loss, injury and death. These fires are unlike others due to the unique way in which they develop. This fact has been recognised for many years by the various standards institutions. including the National Fire Protection Association (NFPA) in the USA, the UK's British Standards (BSI) and the International Standards Organisation (ISO). As a result of the special nature of these fires these institutions have each developed new standards. which define a new classification for cooking oil fires. Tests carried out by the standard agencies around the world have provided new insight into this unique fire hazard.

Unlike more traditional flammable liquids such as gasoline, lubricating oil, paint thinners and solvents, the auto-ignition temperature for cooking oils used for frying can vary immensely. Auto-ignition can occur anywhere from 285°C to 385°C. For auto-ignition to occur, the entire mass of oil, whether in a small pot or in a commercial deep fat fryer, must have been heated to beyond the auto-ignition temperature. However, once ablaze the oil changes composition slightly resulting in a new auto-ignition temperature, which may be as much as 30°C lower than its original auto-ignition temperature. This results in the fire being self-sustaining unless the entire mass of oil is cooled below this new auto-ignition temperature.

In the mid-1960's it was discovered that by applying sodium or potassium bicarbonate powder to burning cooking oil, a unique phenomenon called saponification would occur. All cooking oils, greases and fats contain saturated fats in the form of free fatty acids. When an alkaline extinguishing medium (such as sodium bicarbonate powder) is added, the free fatty acids react with the sodium bicarbonate to form a soapy foam on the surface of the oil - the process of saponification. This foam acts like traditional firefighting foam. It secures the vapours, generates steam and extinguishes the fire. It was discovered that wet chemical agents comprising liquid solutions containing an alkaline mixture (typically potassium acetate, potassium citrate, potassium carbonate or combinations thereof) were far more effective in extinguishing these fires. The combination of a fine mist spray with the saponification characteristics of the agent secured the vapours and cooled the entire mass of oil below its new auto-ignition temperature.

Automatic systems which utilise specially designed nozzles, have been tested on real deep fat fryer fires by the Loss Prevention Certification Board LPCB to LPS1223 Requirements und testing procedures for approval of fixed fire extinguishing systems for catering equipment and have proved extremely effective. These systems use an alkaline wet chemical solution delivered through a piping network to a fine mist nozzle specifically designed and tested for a particular appliance, duct or plenum.

The system can be discharged either manually or automatically in response to a fire in the cooking hood. Automatic actuation is by thermal link detectors located behind the grease filters.

In commercial cooking operations, fryers and other appliances are often turned on early in order to have them heated and ready for cooking when needed. It is not uncommon for kitchen employees to leave the area and perform other tasks while the appliances warm up. Similarly, a cooking facility may be shut down without turning an appliance off or a fryer maybe left unattended. Fires can and, according to incident reports, do occur when fryers are left unattended and no-one is present to use extinguishers. Automatic systems do not rely on personnel being present in order to operate. Automatic suppression is equally applicable to vapour exhaust systems. Fires within these structures can occur unseen and are difficult to detect in their early stages. These particular fires are also difficult to extinguish without a fixed system since accessibility is a problem when using hand held extinguishers.

As well as fast and sure extinguishment of cooking fires, properly tested and regulated automatic systems bring with them an assurance that they will perform as intended in real fire conditions. To gain approval from testing houses such as the Loss Prevention Certification Board (LPCB) these systems are tested under extreme fire conditions. The combination of stringent testing, proven design, reliability and automatic discharge make the Amerex Wet Chemical Restaurant Fire Suppression System the best defence against fires in commercial cooking operations. Quick and effective extinguishment of these fires prevents personal injury, business interruption, equipment loss and structural damage to buildings.

AFS (1993) Ltd. are certified by Amerex to install their system to the LPCB standard. With many years of experience AFS(1993) Ltd have built a large customer base installing systems for insurance companies, other fire protection companies, kitchen hood manufacturers, kitchen design companies and directly with the proprietor.

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• Fixed fire extinguishing systems for catering equipment
• Restaurant Fire Suppression System
• System Examples and Demonstrations
• Combination System
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