Igniting the kitchen safety debate

A fire suppression system is the one piece of kitchen equipment everyone hopes is never used.

But it can be confusing for dealers to choose which type of equipment is most suitable for a particular project, especially when major players in the sector disagree over this point.

One of the leading manufacturers is Fireworks Fire Protection, which provides the Hydramist 15AMPU high pressure watermist system for kitchens.

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Lee Haines, technical key account manager, believes that this product is superior to dry powder or wet chemical fire suppression systems. “Whilst effective at initially suppressing and extinguishing the fire, these traditional systems offer little or no cooling, resulting in a prolonged return to production for the kitchen.

“Additionally they leave a large amount of potentially hazardous residues from the chemical based fire equipment and surrounding areas which must be cleaned up before cooking can re-commence. This leaves a restaurant without a kitchen during this period.”

The Hydramist 15AMPU uses atomised tap water at high pressure to extinguish a fire and prevent re-ignition by cooling the oil and hot surfaces. Upon contact with the flames, these fine droplets of water are said to turn into steam, which Fireworks says will smother and extinguish the fire in less than 10 seconds.

After extinguishing the fire the mist continues to cool the oil and hot surfaces to below ignition temperature in less than 30 seconds, claimed to prevent re-ignition of the fire.

According to Haines: “After activation, next to no clean-up is necessary, as only clean water is used, allowing the kitchen to be back in operation extremely quickly. A further advantage of this system is that smoke is prevented from spreading throughout the kitchen and into other areas, as the smoke particles from the fire are captured by the watermist droplets and the smoke is washed out with the fire.

“Unlike the chemical systems where a defined amount of substance is stored in a cylinder, the 15AMPU will continue to run until switch off so it offers continuous suppression and extinguishment of the risk. The system also doesn’t have to be re-filled which means that it can be back up and running in minutes.”

Haines believes that dealers need to understand the benefits of the systems for their clients. “It is important that they put the right products in to meet the fire safety audit and to make sure that the systems are approved with their insurance companies. It is also beneficial for them to be aware of the ongoing maintenance and ongoing costs.

“Many instances within restaurants are malicious and if the chemical system is actioned then there is a substantial cost to refill it. Also after 10 years these systems have to be stretch tested, which adds another cost that the client may not have been aware on the initial install.” [[page-break]]

Another primary provider, Nobel Fire Systems, takes a different stance. It focuses on special risk fire suppression systems including watermist, wet chemical, dry chemical, gaseous and condensed aerosol active types, plus oxygen reduction fire prevention systems.

Ian Bartle, MD, said: “There are a number of factors that must be taken into consideration when specifying watermist or wet chemical fire suppression systems for kitchen environments. On balance, both types of system achieve fire extinguishment but they do so in very different ways.

“Wet chemicals extinguish fires primarily by chemical interaction with the oils and greases used and produced through the cooking process. This interaction is based on sound and very reliable chemistry whereby the alkaline nature of the suppression liquid changes the composition of the burning oils and fats (fatty acids) and prevents the fire from burning. In doing so the surface of that oil/grease is inerted and can no longer burn.

“A reaction known as saponification takes place and a thick foamy layer forms on top of the oil. This reaction provides some clear advantages as a suppression method, attacking all sides of the fire tetrahedron.

"The primary extinguishing factor is chemical inerting; secondly the liquid is applied as a mist of ultrafine droplets, cooling the oil to below its auto-ignition temperature, and thirdly the chemical liquid forms the foam barrier, shutting off the surface of the oil from air to smother the flames. Last but not least the foamy layer cuts off any access to additional oils to prevent fire growth and spread.”

Bartle feels that watermist only suppresses fire by cooling. “Wet chemical is far more efficient at extinguishing fires using the chemical interaction first and cooling secondary,” he commented.

“This means less liquid is needed to extinguish a fire and to ensure the fire remains extinguished. Water mist does not provide any post discharge securement and is totally reliant on the unhindered provision of very fine droplets of water.

“As the basics of fire suppression dictate oil and water do not mix, so the production of these ultra fine droplets and maintaining those throughout discharge is extremely critical to extinguishment and safety.

“Wet chemical on the other hand uses low pressure fine droplets to absorb as a secondary consideration so will extinguish even if the droplet size is compromised.

“Watermist is totally reliant on cooling, therefore running times to provide security against reflash need to be longer, so the inference that water mist is cleaner than wet chemical literally doesn’t hold water! The quantity of liquid used in wet chemical systems is finite and established through fire testing.”

He urged dealers that the fire suppression system as a whole needs to be considered when choosing what to specify. “The sum of the parts includes fire suppression and post fire security capability, post discharge clean up, environmental impact, ease of installation and service, reliability and longevity, cost and aesthetics.” [[page-break]]

Competitor Amerex is also well known for supplying wet chemical based systems. “Our current range has flexibility at its heart and gives the kitchen planner or kitchen user complete control over the type of system they desire,” said commercial manager Steve J. Evans.

Amerex has a choice of suppression regimes – total flood for total hood protection or appliance-specific products. To compliment this, the systems have a choice of spot (fusible link) or total linear (detection tube) detection options. The Amerex systems are all self-contained, standalone systems that are designed to require no outside utility to operate.

Evans commented: “Over many years, wet chemical agents have been proven effective and efficient. The three pronged attack of wet chemical agents used by our systems on cooking oil fires is essential for secured fire suppression.

“It is a common myth the water systems are quicker to clean up after a fire. All systems require an investigation into the cause of the fire after activating and before resetting; this is standard good practice for all fire systems.

“Like water, wet chemical can be cleaned up with ordinary kitchen cleaners and equipment, and if cooking oils etc. have come into contact with either water or wet chemical they must be replaced.”

He advised: “Professional dealers should first and foremost choose a system that has been independently tested and approved by a recognised test laboratory. In addition to this they should ensure that the system has the approval for the pieces of equipment that they intend to use in the kitchen, as some laboratories only test limited types of equipment.

“On establishing the system is fit for purpose, then aesthetic and ‘ease of use’ factors such as nozzle height, number of agent tanks, ease of cleaning etc. should certainly be considerations a professional designer should asses before recommending a system.

“If the fire system criteria are brought into the design of the kitchen at the early stages, many issues surrounding system specification and installation can be very simply handled before they occur.”

Amerex is in the final stages of approving its new Cobra system to the UL300 industry standard. The firm believes its new product offers enhanced performance and greater flexibility compared with existing systems.

“Adding the only UL300 electronic actuation with electronic detection and Strike panel to the existing pneumatic detection option offers two great options with all the benefits of total linear detection,” said Evans.

“Replacing pipe with stainless steel tube and offering ‘push-fit’ fittings eases installation, reduces install time and increases the aesthetic presentation of the fire system. Reducing the number of nozzle variations will also simplify design and installation.”

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