Pre-engineered chemical suppression systems were developed in the 1960's for the protection of commercial cooking equipment, plenums and ducts. Underwriter's Laboratories (UL) developed a series of fire tests for these systems designed to duplicate the potential fire hazard found in the work place. These tests established specific requirements (and limitations) affecting extinguishing agent, fire detection, piping limitations, nozzle coverage, etc., for each manufacturer who submitted its system for UL testing. Following successful completion of such tests, this data created the installation and maintenance manual for that specific manufacturer.
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 hazard 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 in the 550-600 degree F. range compared to the auto-ignition temperature of most vegetable oils which is at 685 degree F. and higher.
The extinguishing agent employed in pre-engineered restaurant systems is an alkaline base. Fatty acids combine with alkalines to produce a soapy solution in 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.
UL recognized the need for a new set of standards for pre-engineered systems and developed its new UL 300 standard. As might be anticipated, many changes were made in the testing program. A chart comparing former tests with the new requirements is printed on the reverse of this page.
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 the 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.
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.
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.
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.
Copyright (C) 1995, National Association of Fire Equipment Distributors
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