While field-fabricated grease duct systems have been the choice of many engineers over the years, there is now a shift towards purchasing factory-built products. Even though there is a higher upfront investment, contractors are finding its worth it in the long run. Factory-built grease duct systems decrease business downtime, are a much safer choice, are easier to install and maintain and ultimately more cost effective.
Check out the factory-built grease duct feature list below and see why it’s the clear winner!
- Higher Quality Materials: Factory fabricated grease ducts utilize Double-Wall constructions, reducing clearances-to-combustibles without having to apply extra protection. Field fabricated grease ducts require other trades to be present during the installation to fabricate and install protective coverings for combustibles. Additionally, factory-built grease ducts contain a stainless-steel inner, which stays cleaner and is easier to maintain. This material is not affected by fire protection system chemicals. The galvanized, cold roll, black iron materials that comprise the field fabricated grease ducts can react to fire protection chemicals. They also have a rougher surface which can be harder to clean.
- UL Listed: Field fabricated grease ducts do not require UL listings, whereas they are a requirement for factory-built products. Knowing that your factory-built grease duct is proven to take the heat makes code inspections less of a hassle. Some contractors believe selecting a field-fabricated product will excuse a project from having to meet the high standards for which factory-built grease ducts are accountable, but that’s not the case. Field-fabricated grease ducts must still pass a special light, air or water test to ensure zero leakage in the welding. This means multiple inspections and additional business downtime. A listed grease duct must pass strict safety tests, ensuring their dependability and guaranteeing performance. These tests include:
- Clearance-to-combustible testing and determination
- Construction and durability testing
- 30-minute internal fire test at 2,000°F (UL2221)
- Thermal testing for 0” clearance to combustibles (UL2221)
- Overall integrity of entire mechanical assembly (joints, access doors, fittings); no drips or leaks allowed.
- Cylindrical Shape: Field fabricated ducts are rectangular, whereas factory-built ducts are cylindrical with a built-in slope. This slope enables a much greater flow capacity and therefore less resistance for grease to pool. When the buildup begins to occur, the grease runs down and settles at the single lowest point. The grease then drains through a smaller area in the middle at the lowest point, minimizing build-up and allowing grease to flow where it can be safely handled, stored and removed. Rectangular shapes allow grease to pool side-to-side, creating a higher fire risk.
- Modular “No Weld” Design: Contractors and engineers can install factory-built grease ducts in segments due to their modular design. The fact that the factory-built products do not require welding means no squeezing in to tight spaces or manually adding fire wrap to a pipe. This results in increased installation efficiency and a safer working environment.
Interested in purchasing a factory-built grease duct? Check out our list of available options!
