BS EN 12101-8: Smoke and heat control systems. Smoke control dampers

BS EN 12101-8 specifies the design, manufacture, and testing of smoke control dampers - mechanical components that automatically close to prevent smoke spreading through ductwork and across fire-rated boundaries during a fire.

Part of the BS EN 12101 standard family.

How Smoke Dampers Work

A typical smoke control damper consists of:

1. Blade and Frame - A sealed frame containing a moving blade that pivots or slides to close the damper opening
2. Actuator - A motorised actuator (or thermally-activated component) that moves the blade to open or closed position
3. Spring Assembly - A mechanical spring that returns the blade to its fail-safe position if power is lost
4. Limit Switches - Switches that detect fully open or fully closed position and report back to the control panel

Classification System

BS EN 12101-8 classifies smoke dampers across four dimensions: leakage, temperature, velocity, and orientation. Every certified damper carries a classification string that defines its performance in each category.

Leakage Classification - The 1000 Pa Change

Leakage classification defines how much smoke passes through a closed damper, tested at a reference pressure. BS 9991/BS 9999 (2024 editions) now reference testing at 1000 Pa (previously 500 Pa), making the test significantly more demanding and the classifications directly comparable at realistic system pressures.

Leakage is measured in m³/h per m² of damper face area and classified as follows:

E class is the most stringent and is specified where leakage must be minimised to protect escape routes. For most UK smoke control schemes involving protected stairwells or AOV systems, E class is the appropriate specification.

The move to 1000 Pa testing under BS 9991:2024 means that older products certified under 500 Pa testing may not achieve the same classification. BS 9999:2017 has not been updated to mirror this change, but non-residential specifications often follow the same test pressure basis. When re-specifying or replacing dampers, always confirm the test pressure used for certification.

Temperature Classification

Temperature classification defines the fire resistance performance - how long the damper maintains integrity at elevated temperatures. Classifications follow the format [temperature]°C / [duration] minutes:

For most UK residential and commercial buildings, 200°C/60 min is the standard specification. Higher-rise buildings or those with extended evacuation strategies may require 200°C/120 min.

Velocity Classification

The velocity class defines the maximum airflow velocity the damper can handle while maintaining its leakage classification:

Velocity class must be matched to the ductwork design - a damper installed in a duct with higher velocity than its class rating will not maintain its certified leakage performance.

Orientation Classification

Dampers are classified for the installation orientations in which their certified performance is valid:

• H - Horizontal blade, vertical duct installation
• V - Vertical blade, horizontal duct installation
• B - Both orientations certified

Using a damper in an orientation not covered by its certification invalidates the compliance declaration. Always confirm orientation classification at the design stage.

Reading a Classification String

A fully classified damper might be described as:

E 120 / 200°C / 60 min / v10 / B

This means: leakage class E (≤ 120 m³/h·m² at 1000 Pa) / 200°C fire resistance / 60 minute duration / up to 10 m/s velocity / certified for both orientations.

The classification string must appear on the product’s Declaration of Performance and CE marking documentation.

Key Requirements

Fire Performance

Dampers must be tested in a furnace to demonstrate structural stability and sealing during fire exposure to the declared temperature and duration.

Actuation Reliability

Whether motor-driven or thermally-activated, the damper must open and close reliably without jamming. The standard includes endurance tests - typically 500–1000 cycles - to verify reliability across the service life.

Fail-Safe Operation

If power is lost or the actuator fails, the damper must move to its fail-safe position. For most smoke control applications this is open to allow smoke to continue escaping. For dampers in mechanical extract ductwork, fail-safe may be closed to prevent reverse flow.

Manual Override

A manual override on the damper body must allow fire service personnel to manually reposition the damper if the actuator fails.

Specification Checklist

When specifying smoke dampers under BS EN 12101-8, confirm:

• Leakage class - E, S, C or AA, tested at 1000 Pa
• Temperature and duration - e.g. 200°C/60 min
• Velocity class - matched to ductwork design airspeed
• Orientation - H, V or B, matched to installation
• Size - duct cross-section in mm
• Actuation type - motorised or thermally-activated
• Fail-safe position - open or closed
• CE marking and Declaration of Performance confirming all classifications

Installation Requirements

1. Mount the damper square and level in the ductwork
2. Confirm installation orientation matches the certified orientation class
3. Wire actuator and limit switches to the control panel
4. Confirm the blade moves freely without binding
5. Ensure manual override is unobstructed and accessible
6. Label clearly with function, classification, and actuation method

Building control will inspect dampers during construction and request a commissioning certificate confirming correct operation and limit switch feedback to the control panel.

Related Products

• Smoke and Natural Dampers

Related Standards

• BS EN 12101-3 - Extract fans that dampers are paired with
• BS EN 12101-6 - Pressure differential systems using dampers
• BS EN 12101-10 - Emergency power for damper actuators
• Approved Document B & Building Safety Act - UK regulatory context

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