Please fill out the form below and we will get back to you as soon as possible.

Non-Return Dampers (Flap Gates)
Non-Return Dampers (Flap Gates)

Non-Return Dampers (Flap Gates)

Reliable Backflow Prevention and Pressure Relief for Air & Gas Systems

Fibros Heavy-Duty Non-Return Dampers (NRD)—also widely specified across the industry as backdraft dampers or gravity flap gates—are engineered to automatically prevent the reverse flow of gases within industrial ductwork and exhaust systems. Operating on a simple, highly reliable pivot or counterweight mechanism, these dampers open smoothly under forward airflow and close securely when pressure drops. This vital one-way isolation protects critical upstream equipment, such as centrifugal fans and blowers, from backdraft damage, cross-contamination, and environmental exposure.

Request a Quote
  • Technical Specifications
  • Features
  • Industry Applications
Valve Type Single Flap Gate / Non-Return Damper (NRD) / Backdraft Damper
Size Range 150mm to 2000mm+ (Custom sizes available for large exhaust stacks)
Design Pressure Standard low-pressure duct systems (Custom designs for higher pressure available)
Operating Temperature Up to 600°C (High-temperature refractory/alloy options available)
Body / Frame Material Carbon Steel (IS 2062), Stainless Steel (SS304/SS316/SS310)
Flap / Disc Material Mild Steel (IS 2062), Hardox, Heat-Resistant Stainless Steel
Seat / Sealing Type Metal-to-Metal (Standard), or High-Temp Elastomer/Fiber seals for tighter shut-off
End Connection ANSI 150#, DIN, IS standard, or Custom-drilled to match existing duct profiles
Operating Mechanism Gravity-operated, Counter-weighted, or Motorized (for forced override)

  • Automatic & Responsive Operation

  • Counterweighted Precision

  • Heavy-Duty Hinge & Shaft Design

  • Impact Resistance & Durability

  • Effective Sealing

  • Ventilation & Exhaust

  • Fan Protection

  • Power & Steel Plants

  • Environmental Control

Go Back Top