UL 2221 Grease Ducts: For Certainty With Factory-Built Fire-Resistive Grease Duct Enclosures

Why UL Matters: The Importance of Prefabricated Grease Ducts

The UL mark is the most accepted certification mark in the United States — appearing on 22 billion products annually. To ensure UL certification requirements are met, UL Solutions performs quarterly inspections at a production facility, visiting unannounced to examine parts, conduct tests and measure dimensions. If UL uncovers a violation, it can completely halt production of that product at the factory.

Due to these rigorous requirements, many chimney products cannot qualify for UL certification. Field-fabricated grease ducts, for instance, cannot meet those requirements since they aren’t built in a controlled, UL-inspected environment and their final quality and durability cannot be verified.

It’s important to note that new grease duct systems codes enacted since 2000 have made receiving the UL mark even more difficult. These new codes pertain to commercial kitchens and were jointly created by Underwriters Laboratory (UL) and the International Code Council (ICC) Evaluation Services.

At Schebler, all our grease ducts are prefabricated and produced under strict supervision to ensure they meet every UL taxing requirement.

UL 2221 Grease Ducts: Ensuring Food Service Fire Safety

The UL 2221 grease duct standard ensures that the insulation materials used in prefabricated grease duct enclosures, including adhesives, encapsulation materials and facers, provide ample fire protection. Specifically, the enclosure material must have a flame spread value of 25 or less and a smoke-developed value of 50 or less.

UL 2221 Grease Ducts: Testing and Requirements

All factory-built grease ducts that meet UL 2221 grease duct requirements undergo performance tests to ensure safety. The test samples must not only pass these rigorous examinations, but the testing must be minutely observed and recorded. For example, the resulting testing reports must include a description of the samples, material construction, locations and times of the testing and detailed information on all individual parts tested and their performance.

These tests include, but are not limited to, the following.

• Hot-Surface Performance Test, to ensure enclosure materials do not flame, glow, smolder or smoke when faced with temperatures up to 500˚F.
• Steady-State Thermal Transmission Properties Test, which ensures each material always maintains a consistent temperature.
• Noncombustibility Test, to ensure the insulation materials meet the requirements of ASTM E136, a test that simulates a severe fire scenario.
• Internal Fire Test, to ensure ample protection during extreme carbon monoxide buildup.
• Integrity Test, which ensures an inserted cotton waste pad does not glow or flame when placed over any holes or openings in the duct.
• Conduct of Fire Test, to ensure materials do not excessively heat during extreme temperatures and cool sufficiently after that temperature is decreased.
• External Fire Tests, to ensure proper temperature controls and the stability of components during and after a variety of fire and extreme heat scenarios.
• Hose Steam Test, in which all exposed areas of the firestop are subjected to the impact, erosion and cooling effects of a hose stream.

The Certainty of UL Listed Safety

At Schebler, there are many benefits to producing grease duct systems at our sprawling Iowa campus. Because we build our products under strenuous quality control, you can be assured of their consistency and flawless performance. Prefabrication also means easier field installation, resulting in less business interruption and lower costs. Just as importantly, our prefabricated grease ducts can qualify for UL certification.

At Schebler, we have been UL certified since 1994 and have never received a single major violation. This certainty is one of the key reasons we’re the unquestioned leader in providing the finest prefabricated chimney and exhaust systems.

Contact us to learn more about our chimney solutions.