Mechanical Smoke Control, Management and Ventilation System

A smoke control system controls the flow of smoke in a building in the event of a fire. It keeps smoke from spreading throughout the building and gives the building's occupants a clear evacuation route, and prevents further damage to the building's interior.

Smoke control systems (or smoke management systems) are mechanical systems that control the movement of smoke during a fire. Most are intended to protect occupants while they are evacuating or being sheltered in place.

Based on MS 1780:2005 - Smoke Control System Using Natural (Displacement) Or Powered (Extraction) Ventilation Design concepts :

Smoke obscures visibility and can also contribute to fatalities in a fire incident. It is, therefore, increasingly realised that occupant safety in a fire could be greatly improved by providing an efficient smoke extraction system. Moreover, such systems can limit property damage, both directly by reducing the spread of smoke and indirectly by providing better visibility and thus easier access to the seat of the fire for firefighters.

Smoke extraction is one of the tools, which the fire safety engineer may use to ensure adequate fire safety within a building. As such, it should not be considered in isolation but as an integral part of the total package of fire safety measures designed for the building. Thus the need for smoke extraction in any building should be designed in conjunction with the means of escape, compartmentation and active suppression systems.

Smoke extraction should be considered under the following circumstances:

a) Smoke extraction for life safety

Smoke extraction for life safety purposes is of benefit in buildings where means of escape to open-air cannot be achieved within a short period of time and in which the means of escape could be severely contaminated with smoke and become impassable.

Examples include shopping malls, atrium buildings and high rise buildings with phased evacuation, i.e. when a proportion of the occupants are expected to stay in the building throughout the duration or part of the duration of the fire.

b) Smoke extraction for firefighter access

Smoke extraction for fire fighter's access is desirable when:

i) fire brigade access is difficult, e.g. basements and high rise buildings; or

ii) rapid attack on fire is necessary to reduce fire spread and property damage, e.g. high-value warehouses.

In buildings where smoke clearance by natural means may be difficult (e.g. basements, windowless buildings and buildings without openable windows), a powered smoke purging/dilution system is required.

NFPA 5000 requires smoke control systems for underground buildings, smoke-protected assembly occupancies and atria, and smokeproof enclosures for high-rise buildings.

A licensed fire protection engineer (or equivalent) should be responsible for the commissioning who has an in-depth knowledge of the system's intended design and can anticipate failure modes that can be addressed at the time of commissioning. 2. Properly monitor all smoke control system devices and control points.

A fire/Smoke Zone is a space-separated from all other spaces by floors, horizontal exits, or smoke barrIers.

Design goals behind installing smoke control or management systems are to provide a secure environment for occupants and firefighters. Allow tenants a safe environment for escape. Allow a safe environment to facilitate fire department operations.

Smoke Spill fans are designed to control the smoke movement during a fire and must conform to strict standards as detailed in AS1668. These fans must be capable of withstanding high temperatures for short periods.

Smoke extraction systems, designed to effectively remove smoke, heat, and combustion products from the areas affected by fire, and at the same time proportionally supplement the system's output with external compensating air, play a vital role in the maintenance of the fire safety of buildings, escape routes, staircases, etc. Sections of fire ventilation ducts are additionally used to collect and discharge other harmful and toxic extinguishing gases escaping fire areas, as well as in pressure booster systems used to control the air causing overpressure, which is released after exceeding the pressure limit.

The stair pressurisation system is another vital component of a building's fire safety infrastructure. This installation increases the air pressure in a stairwell and makes sure the smoke from rooms does not enter the enclosed area when the doors are closed.

Defining Smoke Control and Smoke Management

A Smoke Control System can be defined as an engineered electro-mechanical system that uses mechanical fans and dampers in cooperation with electronic monitoring and controls to produce pressure differences across smoke barriers that inhibit or facilitate smoke movement. A smoke-control system is used to achieve one or more of the following design objectives:

1. Inhibit smoke from entering stairwells, means of egress, areas of refuge, elevator shafts, or similar areas

2. Maintain a tenable environment in places of refuge and means of escape during the minimum required evacuation time

3. Inhibit the migration of smoke from the smoke zone

4. Provide conditions outside the fire zone that enable emergency response personnel to conduct search-and-rescue operations and to locate and control the fire

5. Contribute to the protection of life and the reduction of property loss

A Smoke Management System can be defined as an engineered mechanical system that, based on its intended purpose, uses mechanical fans, dampers and other methods to remove smoke from a facility under post-fire condition. A smoke management system is applied to one or more of the following intended uses:

1. Roof hatch ventilation for smoke removal in high atrium spaces

2. Smoke exhaust fans in parking garages

3. Pressurisation fans in stairwells and elevator shafts

Understanding the Smoke Control design and installation process can be difficult with challenges at each phase of the project. These systems are generally code mandated based on occupancy type, architectural construction methods, occupancy loads, and other factors. With no single entity or trade being solely responsible for the entire solution, the interdependency across all professional engineering and installation trades is critical for a successful project.