Smoke Introduction

When a fire breaks out in a building the life safety threat is twofold.

Firstly, there is the fire itself and the hot smoke generated in the immediate vicinity.

Secondly, there is the smoke remote to the fire which, if unchecked, spreads rapidly threatening people and property some distance from the fire.

This ‘remote smoke’ is now agreed to be the major contributor toward fatalities and serious injury in structural fires. Hence, there is a growing need for adequate smoke control systems in buildings where deemed appropriate.

Design Needs

Building regulations require large building volumes to be sub-divided into smaller compartments or areas bounded by building elements which resist the spread of fire and smoke. Building a fire resistant wall is a relatively simple task. More complex is providing fire and smoke protection for the doorways which have to be formed if a building is to function.

Doors must have gaps between the leaves and the frame and between the bottom of the door and the floor. These gaps allow doors to be opened and closed easily and accommodate normal building movement. However, if left unsealed they will allow the passage of smoke, fire and sound.

The Lorient solution is to fit an appropriate sealing system which, when properly located and secured, can help in prevent the passage of smoke from one compartment to the next.

The Role of Smoke Doors

Smoke Doors assemblies are designed to improve life safety in buildings by limiting the spread of smoke through door openings and ensuring egress paths remain un-obscured and tenable.

Typical applications include:

Lift lobbies: where smoke doors are utilised to create a refuge and keep the lobby area free of smoke in the advsnt of fire.
Hospitals: where immobility of patients necessitates extended evacuation times and greater levels of protection through smoke compartmentation.
Hotel or multi residential: unit entry type doors, where tenability in the common escape corridor is vital.

Smoke Temperature Classifications

Door perimeter sealing systems will vary depending on the design temperature at which they are required to contain smoke. Smoke is typically defined in three (3) categories:

Ambient Smoke: (or cold smoke) is smoke at a relatively cool temperature. This smoke is quite remote from the source of the fire and has little or no buoyancy.

Medium Temperature Smoke: is defined as smoke at 200ºC. The Building Code of Australia currently requires smoke doors to resist the passage of smoke at 200ºC for 30 minutes. Research has shown that medium temperature smoke is encountered adjacent to the room of fire origin and may also represent the conditions within a room of fire origin during a sprinkler controlled fire scenario.

Hot Smoke: is defined as smoke at temperatures in excess of 600ºC. Typically hot smoke is associated with a fully developed fire scenario in the room of fire origin.

Current Australian Smoke Door Regulations

Defined, a smoke door is a door assembly (including a door, frame, wall fixings, hardware & smoke seals) that restricts the passage of smoke through door openings. Currently a smoke door assembly must meet the ‘deemed to satisfy’ provisions of Specification C3.4 of the Building Code of Australia (BCA), unless otherwise specified.

Specification C3.4 requires that “Smoke doors must be constructed so that smoke will not pass*¹ from one side of the doorway to the other” and provides the following “deemed to satisfy” guidance:

A smoke door of one or two leaves satisfies Clause 3.1 if it is constructed as follows:

(a) The leaves are side-hung to swing—

(i) in the direction of egress; or

(ii) in both directions.

(b)

(i) The leaves are capable of resisting smoke at 200°C for 30 minutes.

(ii) Solid-core leaves*² at least 35 mm thick satisfy (i).

(d) (i) The leaves are normally in the closed position; or

(ii) (A) The leaves are closed automatically with the automatic closing operation initiated by smoke detectors, installed in accordance with the relevant provisions of AS1670.1, located on each side of the doorway not more than 1.5 m horizontal distance from the doorway; and

(B) in the event of power failure to the door, the leaves fail-safe in the closed position.

(e) The leaves return to the fully closed position after each manual opening.

(f) Any glazing incorporated in the door complies with AS1288.

(g) (i) If a glazed panel is capable of being mistaken for an unobstructed exit, the presence of the glass must be identified by opaque construction.

(ii) An opaque mid-height band, mid-rail or crash bar satisfies (i).

* Unfortunately this specification creates some confusion, particularly with regard to:

¹ the perceived zero smoke leakage requirement

² the “solid core” door construction, which remains undefined

³ the requirement for the smoke seals to be fitted to the door leaf (leaves) to comply.

Performance Based Soliutions

The Building Code of Australia allows provision for the use of “ Performance Based Alternate Solutions”.

The introduction of two important Australian Standards has allowed fire engineers and building practitioners to specify smoke doors with quantifiable levels of performance with the knowledge that installed assemblies will meet their building design requirements. They are:

AS6905:2007– Smoke Doors

AS1530.7:2007– Smoke control assemblies –Ambient and medium temperature leakage test procedure.

AS6905 covers the specification, construction, installation and identification of smoke doors. The standard requires that assemblies are tested in accordance with the conditions detailed in AS1530.7, and most importantly it defines the maximum allowable smoke leakage rates for single and double door assemblies at prescribed temperature and pressure differentials.

SECTION 2 DESIGN REQUIREMENTS

2.4 Leakage Performance For Smoke Doors

(a) Single leaf smoke doors—40m³/h at medium temperature conditions (25m³/h corrected to Standard Reference Conditions¹), at a pressure differential of 25 Pa after exposure at 200ºC for at least 30 min when subjected to a test in accordance with AS1530.7.

(b) Double leaf smoke doors—65m³/h at medium temperature conditions (40m³/h corrected to Standard Reference Conditions¹), at a pressure differential of 25 Pa after exposure at 200ºC for at least 30 min when subjected to a test in accordance with AS1530.7.

¹ The Standard Reference Conditions are defined as the temperature of 293.15 K (20ºC) and the pressure of 101,325 Pa.

AS1530.7 is a test method that allows the measurement of smoke leakage from one side of a door assembly to the other under elevated temperature test conditions.
The test methodology involves fitting a full size door assembly, including all essential hardware, to an approved test chamber in which temperature and pressure conditions are controlled. Ordinary air is used in the chamber, simulating the carrier gases of real smoke. Pressures are applied and resulting “leakages” through the test assembly are measured to determine its effectiveness as a barrier to resist smoke. Measurements are taken at pre-determined periods that provide data to align with the BCA deemed to satisfy regime of 30 minutes exposure at 200°C.

Lorient Smoke Sealing Solutions

Whether ‘Performance Tested’ or BCA compliant, Lorient can offer a variety of door sealing systems to suit a variety of applications.

Performance Tested Solutions – tested to AS1530.7 with proven medium temperature smoke leakage rates across various pressures, as per the leakage rate guidelines set out in AS6905.

These systems incorporate a complete tested door assembly, including a proprietary door and selected performance door seals, combining to cater for door movement and provide the best leakage rates possible within the specified parameters.

‘Deemed to Satisfy’ BCA Solutions– for applications with NO Fire-Engineered specification, designed to meet the provisions set out in Specification C3.4 of the Building Code of Australia.

The sealing components utilized for these applications are generally extruded silicone, or materials with a proven temperature resistance above 200ºC, fitted to the door leaf (leaves).

Lorient Australia have performed numerous ambient & medium temperature tests with door companies on a variety of Proprietary² doors.

Together with a detailed knowledge of fire & smoke containment, we can confidently offer the performance tested and recommended ‘deemed to satisfy’ solutions to various smoke door applications.

For further information on the smoke performance of the Lorient range of door sealing solutions, please feel free to contact our Technical Department for advice.

² Please contact Lorient Australia for detailed information on relevant tested Proprietary door systems.