FRP Duct and Hood for Fume Extraction Systems

Exhaust ducts and ventilation hoods in pickling lines, plating shops, and chemical storage rooms carry acidic or alkaline fumes that corrode galvanized steel within months. FRP (glassfiber reinforced plastic) ducts are the standard solution for corrosive air handling. This article explains how FRP ductwork is specified and installed.

Why FRP Ductwork

• Smooth internal surface that resists particulate buildup and keeps pressure loss low.

• Resistance to a wide range of acids, alkalis, and solvents at typical exhaust temperatures below 80 °C.

• Light weight, which reduces roof and support loads compared with stainless steel.

• Ease of field fabrication: sections can be joined with butt-and-wrap joints on site.

Design Considerations

Size the duct for the required capture velocity at the hood face; avoid high velocities that increase noise and pressure loss. Include access doors at bends and junctions for cleaning. Provide drain points at low spots to remove condensate. For high-temperature exhaust (above 80 °C), switch to a vinyl ester or phenolic resin system.

Hood Types

Choose a lateral slot hood for tanks with frequent operator access, a canopy hood for overhead capture, or an enclosed booth for high-emission processes. The hood face velocity should be 0.5 to 1.0 m/s for general fume and higher for toxic or dense vapors.

Installation

Support ductwork at intervals suitable for the diameter; FRP duct is rigid but expands and contracts with temperature. Install flexible connections at the fan to isolate vibration. Ground the duct if explosive dust is present, even though FRP itself does not conduct.

Conclusion

FRP duct and hood systems deliver long service in corrosive exhaust duty. Correct hood velocity, drainage, and support spacing determine how well the system performs over decades.

References

• AMCA 26 — Field Performance Measurement of Fan Systems

• ACGIH Industrial Ventilation Design Guide