Creative Viewpoint

Volume 20

 

Are water sprinkler systems sufficient to contain commercial kitchen hood fires?

  

     A fire triangle involves the elements of fuel, oxygen and ignition temperature. Generally, if two elements in the fire triangle are addressed, the fire can be effectively contained. However for commercial kitchen hoods, the practice today involves addressing all three elements of the triangle. This is because fire hazards are substantially increased in a hot kitchen environment and statistics now show that 40 percent of all kitchen fires actually start in a hood. In some third world countries CKP have consulted in, developers had opted for sprinkler systems for kitchen hoods. Sprinkler systems address only one aspect of the fire triangle. They only address the ignition temperature aspect. 

     Misting systems, which were used in the earlier generations of fire suppression, which is now not practiced, addresses a second aspect. They would additionally deal with the elimination of oxygen molecules; by displacement using water molecules. This system replaced the CO2 system which also used the displacement principle. CO2 is now banned in the USA because it displaced critical oxygen levels ie crucial oxygen that was needed for people caught in a fire environment.

     The chemical system was then later introduced, starting with dry powder (hard to clean); and the subsequent evolution of wet chemical (such as ANSUL R102) and now the sprinkler chemical system (such as ANSUL PIRANHA). The chemical systems react with the fuel (grease) to form a saponified substance, almost like soap, which is hard to reignite. The latter forms a layer that separates the underlying grease from oxygen. Therefore, this system addresses all 3 aspects of the fire triangle. The Piranha system not only doses chemical but then continues to sprinkle water for 15-30 seconds.

     In a more recent discovery, it was noted that after a conflagration, when reaction temperatures are high and the fuel supply fails to turn off, reignition could potentially occur. Therefore, continued water dispensation prevents re-ignition. The most expensive system in the industry for addressing kitchen fires is the Piranha System. Most foodservice consultants tend to specify the cheaper R102, which is the minimum standard required. In line with NFPA 96 we are only providing nozzles for gas fired equipment and those with deep seated fires like tandoors. For electrically operated equipment, no nozzles will be provided. In this way we can potentially keep the cost of the Ansul system down and are still in line with the code. Typically for all CKP projects, we do exceed the code and ensure that all equipment are protected, regardless of the type of fuel employed.

It may be the prevalent practice in some countries to go with sprinklers and quite a bit of capital expenditure can be saved on this as opposed to a wet chemical system. However, this may not be deemed as sufficient to provide the required levels of fire safety required in a hot kitchen. It may also not meet the requirements of fire safety spelt out within the insurance provisions of the hotel management company.

 

Franke’s new coffee machine.

 

     Franke’s SPECTRA coffee machine series offers remarkable compactness in terms of width, measuring only 300mm(W) x 580mm(D) x 710mm(H). Worth mentioning is, this unit can be fitted with a maximum of 3 beans hopper (slim hoppers) on a mere 300mm width. Of the 3 hoppers, the user has the flexibility to custom specify the sets of internal grinders, either 3 nos. to do 3 coffee beans OR ; 2 sets of grinders for 2 coffee beans + 1 nos. without grinder to do powdered product (instant coffee or chocolate) (OR 1 + 2 vice versa.) The technology advancement includes the spout, which will auto-adjust its height upon sensing the size of the glass used. The user also has 3 choices of control panels to be specified on the machine.

 

SPECTRA S

The 3 SPECTRA models under this line are: -

i) SPECTRA S – stands for SPECTRA Specialty – For brewing specialty coffee (comparable to EVOLUTION).

ii) SPECTRA X – stands for SPECTRA Extra Large – It’s the market’s first Beans-to-Pot Coffee Machine; for mass production. This is meant for producing filtered coffee, therefore it cannot be attached with a milk chilling system.

iii) SPECTRA I – stands for SPECTRA Dispenser – This is a standard dosing machine, does not come equipped with any grinders and it is intended for dosing instant powdered drinks only.

 

Energy Saving Dishwasher

 

     Winterhalter has recently launched its new energy saving hood type dishwasher models - GS502, GS515 Energy and Energy+ series. With the aid of an “exhaust air” heat exchanger, these models utilize the transfer of heat from the exhaust air to heat up the incoming cold water. This thermal exchange process allows the exiting exhaust air to become cool whilst the incoming water absorbs this dissipated heat. As this incoming water rises to its desired operational temperature, less electrical power is required by the machine to traditionally heat the water. In addition, the Energy+ series utilizes an extra “waste water” heat exchanger, further reducing power consumption. This technology would certainly be applicable in countries with high electrical energy costs and where incoming water temperatures do not exceed 200C. However, if high temperature hot water services are readily available, this technology would be inefficient and unsuitable. In short, this heat recovery technology not only reduces the total power consumption and operating costs, but also improves the surrounding air quality.

Model No

Dimensions

Total Connected Load

Standard GS502

635 X 749 X 1469mm, height hood open: 1932mm

15.5KW

GS502 Energy

635 X 749 X 2145mm, total system height: 2145mm

12.5KW

GS502 Energy+

635 X 749 X 2145mm, total system height: 2145mm

0.95KW

Standard GS515

735 X 749 X 1530mm, height hood open: 2050mm

15.6KW

GS515 Energy

735 X 749 X 2235mm, total system height: 2235mm

12.6KW

GS515 Energy+

735 X 749 X 2235mm, total system height: 2235mm

09.6KW

 

Kitchen Exhaust Misconception

      

     Most kitchen operators and owners are relying on the notion that the greater the exhaust capacity, the better you can rid of the fumes and contaminated grease laden air in the kitchen. That would only be partially correct as there are many factors impacting capture and containment. There are particular considerations whenever one is putting up a kitchen exhaust system and one of them is the required levels of air pressure within the kitchen.

    It was always a common issue in previous kitchen installations that the doors leading to the dining area or sometimes service doors leading to corridors tend to be difficult to open or to keep closed. This is due to excessive negative pressure in the kitchen. There has to be a minimum threshold of negative pressure in the kitchen being created by the exhaust hood to suck out cooking fumes and heat but not to the extent of making the doors difficult to open or close. The latter happens when exhaust hoods are not equipped with proper air dampers or a make up air system thereby lending credence to the important principle of kitchen air balance. Increasing the exhaust capacity alone does not help beyond a certain point as this creates new problems like increased audible air turbulence at the ductworks and fan motor noise.  A secondary but serious consequence of increasing exhaust capacity is the resultant increase of air drafts towards the cooking zones which act as cross currents impacting capture and containment. One has to address ventilation on a holistic point of view.

     Latest hood designs incorporate a return air cavity at the face of hood complete with adjustable diffusers and duct collar to allow fresh (for temperate climates) or tempered (for tropical climates) air supply to the kitchen. This fresh or tempered air supply takes care first of all the air pressure balance by replacing the air vented thru the exhaust. Although it does not completely compensate the volume of air loss, it does provide enough air diffusion surrounding the cooking area creating optimum air replacement and capture causing a laminar flow of contaminated air and heat thru the hood and minimizing unnecessary turbulence. By doing this the negative pressure requirement is now more easily managed.

       Increasing the exhaust capacity will also proportionately increase your make up air volume, and by doing so will also increase your hot or cold air tempering system and will also increase the fan motor sizes which on the overall will be very expensive. Always seek professional advice from relevant engineering trades or from foodservice consultants for issues pertaining to kitchen ventilation and equipment heat outputs.

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Creating Forefronts in Foodservice Design

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