Door Fire Blocks

Ducting Express offer a range of circular and rectangular intumescent fire blocks for use in doors, walls and ducts. 

Fire dampers are passive fire protection products often used in heating, ventilation, and air conditioning (HVAC) ducts to prevent the spread of fire inside the ductwork which travels through fire-resistance rated walls.

What happens to an Intumescent fire block when there is a fire?

An intumescent is a substance that swells as a result of heat exposure, thus increasing in volume and decreasing in density. Upon exposure to elevated temperatures indicative of a fire, Intumescent fire blocks expand to many times their normal size, forming an incombustible mass which seals its vent, preventing the spread of fire and hot smoke. These grilles differ from regular fire dampers in that they have no moving parts.Those dampers use a fusible link which splits to allow a curtain type blade pack to extend and block off the duct.

Features and Benefits of Intumescent fire dampers

There are many advantages of installing these air transfer grilles, some of these are:

  • Tested in flexible walling and ducting to BS476: Part 20: 1987, offering up to 120 minutes fire integrity 
  • Tested in timber doors to BS EN1634-1:2014, offering up to 60 minutes fire integrity 
  • Designed to operate without any command from an operator or building maintenance system 
  • No moving parts therefore no maintenance required 
  • Simple to install in doors, walls and ducts 
  • Slim design; only 38mm thick 
  • Approximately 60% free area 
  • Large range of standard and non-standard sizes available 

Installation and Maintenance 

Intumescent fire dampers are suitable for vertical installation in fire doors, plasterboard walls and ductwork. Fire damper installation should only be carried out by competent persons. As safety devices, correct operation is reliant on correct installation.

The dampers have predrilled holes in the side component, and are installed by screwing through the side, into the aperture wall. Gaps around the grille perimeter can be sealed using an intumescent sealant on both sides. When installing in circular ducts, screw through the duct wall into the air transfer grille frames and, as with installations in walls, you can seal the perimeter with an intumescent sealant. 

Since there are no moving parts to go wrong, intumescent fire dampers are easily maintained and should just be periodically cleaned using a damp cloth. As the intumescent dampers use a physical/chemical reaction to work, the product should not be used in areas of high/constant humidity or immersed fully in water.

Once exposed to elevated temperatures or flames resulting in the damper intumescing to any extent, the damper must be replaced.

Intumescent fire dampers are available in a wide range of sizes to suit all applications. Should you not see the size you need today please contact our team on 01455 616 444. As well as the standard sizes we hold in stock, non-standard sized air transfer grilles can be made to order. 

Not sure what kind of fire damper is suitable for your application? Our team can advise you on the most suitable type of passive fire protection products. Contact us today.