Field fabricated or factory-built? Although many existing systems are field fabricated, most engineers, contractors and building owners opt for factory-built commercial kitchen exhaust systems when replacing existing or installing new. Why are factory-built systems preferred? The primary reason is safety, but factory-built commercial kitchen exhaust ducts are easier to install and maintain.
UL – 1978 Standard for Grease Ducts covers factory-built grease duct assemblies and requires manufacturers have grease duct tested to receive UL listing. The tests are performed to guarantee the safety and reliability of the duct under hazardous conditions: continuous operation at 500°F and intermittent operation at 2,000°F, simulating a grease fire. Some of the tests that factory-built grease ducts are submitted to are:
- Joint Leakage and Torsion
- Vertical support
- Side impact
- Longitudinal force
- Load test for grease duct elbows
Field-fabricated kitchen exhaust ducts are required to meet ASTM E 2336-04 – Standard Test Methods for Fire Resistive Grease Duct Systems which is a materials specification. The individual materials in a field fabricated system are tested, but the assembly is not. Manufacturers bearing the UL 1978 listing have had the assemblies tested, clearly a higher level of safety.
INSTALLATION & MAINTENANCE
Factory-built grease ducts make your job easier. You can install them in segments thanks to their modular design, and the ‘no-welding’ construction affords more wiggle room in how the kitchen hood exhaust duct is installed. No squeezing into tight spaces to weld or to manually add fire wrap to a pipe. You can clean, inspect, and rehab an existing system very quickly during off-hours — which is big advantage for retrofit projects.
Round or rectangular? Although round grease ducts result in the lowest maintenance, sometimes it isn’t always possible to fit round ductwork within the ceiling cavity. DuraSystems DuraDuctTM KEX is the largest listed kitchen exhaust duct system in the industry. DuraDuctTM KEX system allows flexibility in the design of Type I and Type II commercial kitchen exhaust duct systems to achieve the required airflows in shallower ceiling spaces.
United Energy Products is ready and able to assist you with the design and purchase of your factory-built commercial kitchen exhaust system. Reach out to us at firstname.lastname@example.org for all your grease duct needs.