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UL 300 Information


On November 21, 1994, a new Underwriters Laboratories test standard entitled UL 300, Fire Testing of Fire Extinguishing Systems for Protection of Restaurant Cooking Areas, went into effect. This new standard is the result of changes in fire hazards involving commercial cooking equipment.

Pre-engineered chemical suppression systems were developed in the 1960’s for the protection of commercial cooking equipment, plenums and ducts. Underwriters Laboratories (UL) developed a series of fire tests for these systems designed to duplicate the potential fire hazard found in the workplace. These tests established specific requirements (and limitations) affecting extinguishing agent, fire detection, piping, nozzle coverage, etc., for each manufacturer who submitted its system for UL testing.

Fats and Temperature

At the time that these tests were developed, rendered animal fat (lard) was typically used in commercial kitchens to fry various foods. Commercial cooking operations, appliances and supplies have changed greatly since the 1960’s. Health concerns have reduced the use of lard. Efforts to cook faster have caused the use of insulated ‘high efficiency’ fryers that heat faster and cool slower. Restaurant suppliers estimate that 70-75% of commercial kitchens use vegetable oils for frying in high-efficiency fryers.

These changes have significantly altered the fire hazards in cooking areas. Lard has a large percentage of saturated fat, whereas vegetable oils have a very low percent of such fatty acids. The auto-ignition temperature of most animal fats is in the 550-600 degree F. range compared to the auto-ignition temperature of most vegetable oils which is 685 degree F. and higher.

The extinguishing agent employed in pre-engineered restaurant systems was an alkaline base. Fatty acids combine with alkalines to produce a soapy solution in a process known as saponification. Thus, when a suppression system is discharged on a burning deep fat fryer containing rendered animal fat, a soap blanket is formed, cutting off the oxygen supply and containing the fire until the fuel (animal fat) is cooled below its auto-ignition temperature.

A similar fire involving vegetable oils creates a different set of circumstances. With only a limited amount of fatty acids, saponification is greatly reduced and the higher temperature of such fires, enhanced by the insulation in a high efficiency fryer, causes the soap blanket to break down. Thus, the extinguishing capability of the fire suppression system is reduced.

Time for Change

UL recognized the need for a new set of standards for pre-engineered systems and developed its new UL 300 standard. Unfortunately, UL did not require a model number change for those manufacturers who will be modifying existing system designs to comply with the new UL 300 test standard. The only requirement is the issuance of a new installation and maintenance manual containing whatever changes and modifications found necessary for compliance with the new standard plus the effective date of the revised publication. This could lead to some confusion because of similarities between the old and new system components.

Buyer Beware

We must assume that there will be a small number of sellers/installers who will attempt to furnish either new or used systems that were tested to the former standard. Such fire suppression systems would be inadequate to deliver the additional coverage found to be necessary for today’s fire hazards.

UL-300 and the Fire Service

How can a local authority determine if the system complies with the new UL 300 standard? It is suggested that the contractor be required to include with his submittal package a copy of the manufacturer’s installation and maintenance manual that would specifically indicate it is in compliance with the new standard and dated November 1994 or later.

The new UL 300 standard assures fire protection for a hazard that has gone through many changes. It presents the most significant advancements in testing of pre-engineered restaurant fire suppression systems in the past 20 years. Without careful scrutiny by local authorities, such changes would have little effect if fire suppression systems are allowed to be installed under the old listings and manuals.

Final Remarks

The new UL Standard 300 addresses the problems in fire protection for commercial cooking environments which reflect changes in our diet and the way we prepare food. All of these changes have resulted in fires which are hot, stubborn and difficult to extinguish. Nozzle coverages and placement options are likely to decrease while extinguishing agent amounts increase.

Pre-engineered systems for commercial cooking operations will become more detailed, more technical, and more expensive. They will also be safer, more reliable and perform their primary function better than ever before.

For additional information on UL-300 extinguishing systems or other fire prevention and suppression systems, contact the Risk Improvement Department of EMC Insurance Companies.

Copyright (C) 1995, National Association of Fire Equipment Distributors