# Fire Dampers — Types, Ratings and Installation

> A fire damper is a closure device inside ductwork at the point it crosses a fire compartment boundary, restoring the fire resistance of the wall or floor the duct passes through. A fire damper closes on heat via a fusible link; a fire-smoke damper is motorised and closes on a signal from the fire alarm.

## What it is

A **closure device inside ductwork** at the point it crosses a fire compartment
boundary, restoring the fire resistance of the wall or floor it passes through.

## Types

| Type | Actuation | Typical use |
| --- | --- | --- |
| **Fire damper** | Fusible link, heat | General compartment crossings |
| **Fire-smoke damper** | Motorised, alarm signal | Escape routes, pressurisation |
| **Smoke damper** | Motorised, detection | Smoke control systems |
| **Ceiling radiation damper** | Heat | Ceiling penetrations in rated floors |

## Specification at a glance

| Property | Typical specification |
| --- | --- |
| Rating | Matches the wall or floor rating — 60, 120 minutes |
| Standard | EN 15650 or UL 555 |
| Link temperature | Commonly 72°C for fire dampers |
| Frame | Purpose-made installation frame, built into the wall |
| Actuator | Spring-return on motorised types |
| Access | Panel sized and positioned to reach the damper |

## Installation is where the rating lives

A correctly rated damper installed badly gives no protection at all:

- The damper must be **built into the wall** on its installation frame, not
  hung off the duct beside it
- The gap around the frame must be fire-stopped with a **tested** system
- The duct must be able to fall away in a fire without pulling the damper out
- An **access panel** must reach the damper for testing and resetting
- Links and blades must be **clear of paint** and free to move

## Where projects go wrong

- **No access panel.** The damper can never be tested or reset.
- **Fixed to the duct**, not the wall.
- **Fire stopping done with general-purpose sealant** rather than a tested
  system.
- **Rating lower than the wall** it penetrates.
- **Fire-smoke damper specified but wired to nothing**, so it never closes on
  alarm.

## Standards referenced

Compartmentation and services provisions under **NBC 2016, Part 4**. Fire
damper requirements under **EN 15650** and **UL 555**.

## Frequently asked questions

### Why are fire dampers needed at all?

Because a duct passing through a compartment wall punches a hole in the fire separation the building's fire strategy depends on. Without a damper, fire and smoke travel freely from one compartment to the next through the ductwork, defeating the compartmentation entirely. The damper restores the rating of the wall at the point the duct crosses it.

### What is the difference between a fire damper and a fire-smoke damper?

A fire damper closes on heat, usually via a fusible link that melts at a set temperature, and it stops flame spread. A fire-smoke damper closes on a signal from the fire alarm or smoke detection system, so it acts on smoke long before temperatures rise. Since smoke kills before fire reaches most people, escape routes and pressurisation systems typically require the motorised fire-smoke type.

### Why do fire dampers fail inspection so often?

Almost always installation rather than the damper itself. The most common defects are no access panel to reach the damper, the damper fixed to the duct instead of built into the wall with a proper installation frame, the gap around the frame not fire-stopped correctly, and links painted over during finishing so they can never release. All four are invisible once the ceiling closes.

## Sources

- [NBC 2016, Part 4](https://www.bis.gov.in/standards/national-building-code/?lang=en) — Fire and life safety — compartmentation and services
- [EN 15650](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Ventilation for buildings — fire dampers
- [UL 555](https://www.shopulstandards.com/) — Standard for fire dampers

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Source: https://hagerstone.com/materials/fire-damper