Last edited 08 May 2024

Fire damper

1 Overview
2 Types of fire dampers
3 Requirements
4 Managing the installation
5 Related articles on Designing Buildings
6 External references

[edit] Overview

Fire dampers are devices designed to impede the spread of fire through walls, floors and partitions. The term 'fire damper' is defined by Approved document B, Fire Safety, Volume 2, Buildings other than dwellinghouses, as a: 'A mechanical or intumescent device within a duct or ventilation opening that operates automatically and is designed to resist the spread of fire.'

Fire dampers are installed in the ducts of heating, ventilation and air conditioning systems which penetrate fire-resistant constructions and will automatically close on the detection of heat. Typically, a thermal element will melt and allow springs to close the damper, which will stop the fire from migrating into an adjoining compartment.

Smoke dampers are designed to prevent the flow of smoke and products of combustion, and 'fire and smoke dampers' combine both functions. Smoke dampers and combined dampers are generally resettable, and are operated electronically by smoke and fire detectors, as smoke may be present even where temperatures are not elevated.

Approved document B defines a fire and smoke damper as: 'A fire damper which, in addition to the performance of the fire damper, resists the spread of smoke.'

From 1 July 2013, it became a requirement under the Construction Products Regulation for all new fire and smoke dampers used in UK buildings to be CE-marked to indicate product compliance (ref. CIBSE Journal). This recognises the testing standard BS EN 1366 – Fire resistance tests for service installations, which contains test procedures which ensure dampers are installed appropriately.

[edit] Types of fire dampers

There are three main types of fire dampers:

Curtain fire dampers which include a folded curtain held at the top by a thermal element.
Intumescent fire dampers which contain elements that expand when heated.
Single and multi-blade fire dampers which pivot when released.

Static fire dampers can only be used where ventilation shuts down in the event of a fire. Dynamic fire dampers can resist air pressure where ventilation systems continue to operate.

[edit] Requirements

Ductwork should comply with:

Building Regulations Approved Document B,
BS 5588: Part 9
NHS HTM 2025 ventilation in healthcare premises.

BRE examination into the fire-resistance requirements for ductwork and dampers states that: "Ductwork passing through compartment and sub-compartment walls should be provided with fire dampers."

Fire and smoke dampers should comply with Product standard EN15650 requiring testing to EN1366-2 and classification to EN13501-3. EN15650 Fire Dampers (FD) and Fire and Smoke Dampers (FDS) products are intended to maintain compartmentation where HVAC ventilation ductwork breaches compartment boundaries by closing and remaining closed in a fire condition.

EN15650 Product standard for Fire Dampers.
EN1366-2 Testing Standard for EN15650 products
EN13501-3 Classification standard for EN15650 products.

[edit] Approved document b

Where a fire compartment is a building or part of a building comprising one or more rooms, spaces or storeys, that is constructed to prevent the spread of fire to or from another part of the same building or an adjoining building.

[edit] Ventilation ducts and flues passing through 'fire-separating elements'

10.12 If air handling ducts pass through 'fire-separating elements', the ... integrity...of the elements should be maintained by one/+ of the following methods...in most duct systems, a combo is best.

1) thermally activated fire dampers
2) fire resisting enclosures
3) Protection using fire resisting ductwork
4) Automatically activate fire and smoke dampers triggered by smoke detectors...except in the case of kitchen extract ductwork, 1 and 4 are banned -> no dampers allowed as build-up of grease within the duct can prevent dampers working property.

[edit] Ducts passing through 'protected escape routes'

10.7 A 'protected stairway' should be served by a SEPARATE ventilation system (1 per each protected stairway)
10.8 An FSD should be provided where ductwork traverses in/out of the 'protected escape route' it serves. Operated by smoke detector or fire alarm. ALTERNATIVELY: METHOD IN 10.15, 10.16, D 10.2 AND 10.3 as below:
10.15:Thermally activated dampers should NOT be used for extract ductwork passing through the enclosures of 'protected escape routes'...because smoke can spread to it.
10.16: An 'ES classified' (leakage specifications in BS EN1366-2) FSD activated by a fire alarm/smoke detection system may also be used for 'protected escape routes'.

Diagram 10.2 - Ducts passing through 'protected escape routes' - method 2/3. Ductwork going through a 'protected lobby' or 'protected stairway' should be fire resisting to match the fire rating of the walls of the protected escape route.

[edit] Sleeping risks

10.22 Where the use of the building involves a 'sleeping risk', fire dampers or fire and smoke dampers should be actuated by BOTH

a) Smoke detectors AND
b) Thermally actuated devices

Another good source of official guidance is provided in 'Firecode - fire safety in the NHS Health Technical Memorandum 05-02: Guidance in support of functional provisions for healthcare premises', this includes definitions and diagrams. The document was accessed in Feb 2020 from NAHFO 'National Association of healthcare fire officers' here.

This document defines subcompartments as: "areas into which the building can be divided to reduce travel distance and which provide 30 minutes’ resistance to fire".

[edit] (NHS Fire code) Elements

[edit] Compartment walls, floors & protected shafts FSD

6.16 & 6.81 Fire dampers in ductwork passing through compartment walls should be actuated in accordance with BS 5588-9 and, by the operation of the alarm and detection system in the compartments either side of the compartment wall (Consider C&E)

[edit] Sub-compartment walls FD

6.82 In sub-compartment walls, dampers activated by a suitable thermal release device set at 74°C may be used (see Figure 10)

[edit] Hazard room enclosures FD

6.37 Ductwork passing through, or over, 'fire hazard rooms' should be provided with fire dampers in accordance with Figure 11. (Note ii - fire dampers operated by fusible links)

[edit] Cavity barriers FD

6.38 Ductwork passing through cavity barriers should be provided with fire dampers in accordance with Figure 10?

[edit] Protected corridors.

No specific reference in Firecode but FD would be considered acceptable in most instances (Note. AD B requires FSD).

[edit] Specialist Ventilation

(HTM 03-01) Areas of ‘Specialist Ventilation’, where for operational reasons stopping ventilation is not acceptable - fire rated ductwork would be specified instead of dampers (e.g. isolation facilities, fume cupboard extracts & kitchen hood extracts).

Fire rated ceilings above ductworks can also negate the need for FSDs.

[edit] (NHS Firecode) Damper Location Requirements - Exceptions

5.27 Ductwork passing through sub-compartment walls need not be provided
with automatic fire shutters provided that:

a. the duct serves only one sub-compartment; and
b. the ductwork and supports have a minimum period of fire resistance of 30 minutes (integrity only) when tested in accordance with the relevant parts of BS 476. (See Figure 11.) (Figure 11 actually refers to hazard rooms not sub-compartments!)

From figure 11 It also appears that a 30 minute non-demountable fire rated ceiling below the ductwork would negate the need for fire dampers

[edit] (NHS Firecode) Stipulations for performance and detailed specifications :

Fire dampers should conform to BS EN 15650:2010. They should have an E classification equal to, or greater than, 60 min.Fire and smoke dampers should also conform to BS EN 15650:2010. They should have an ES classification equal to, or greater than, 60 min.

[edit] Managing the installation

Ensuring effective fire damping requires careful design, specification and installation, with care taken to ensure penetrations are properly formed and dampers are properly sealed. Systems should be inspected and tested regularly and this requires that proper access is provided in the building design.

The principal designer and principal contractor have a role in ensuring the proper design and installation of fire dampers, and installations will be subject to approval under the Building Regulations.

BS999 provides guidance on the regular testing of the fire and smoke dampers, which should generally be tested once per year.