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Air Dampers

For ventilation systems

Our range of Air Dampers break down into three basic categories as follows:


Motorised Dampers

This type is simply used for fitting in to a duct system where it is necessary to close-off the airway when the ventilation plant has stopped, or for use where a fire protection system requires a sealed space into which a fire suppressant gas can be discharged without major loss. The standard type is not gas tight. We can supply a low leakage version that includes blade seals and side gap shim seals. They are fitted with one or more Belimo electric actuators, 240 or 24 volt, with three actuation modes,

power open, spring close

spring open, power close

power open, power close.

The standard construction uses a 2mm pre-galvanised steel welded 200mm deep casing with 50mm un-drilled flanges. The blades are pre-galvanised parallel opening 'Z' sheet steel with zinc plated spindles running in nylon bushes. Where required for gas-tight applications the blades are fitted with seals and the side walls fitted with spring loaded stainless steel shims and using stainless steel spindles running in bronze bushes.

Gravity Flap Dampers

This type is used at the air discharge of a system, whereby the throughput of air blows the blades into the open position. When the airflow stops, they will automatically close to prevent a backflow of air or draught.

The standard construction uses a 2mm pre-galvanised steel welded 200mm deep casing with 50mm un-drilled flanges. The blades are pre-galvanised sheet steel with zinc plated spindles running in nylon bushes.

Fire Dampers


Please follow this link here for fire dampers

This type is used to protect a duct space or area against fire escape. There are two principal types, either the curtain type, which will snap shut upon receiving a signal (then requiring manually resetting), or the motorised type that can be opened or shut by use of an actuator. They normally have a minimum 4 hour fire rating.

Resistance to Airflow


The motorised and fire damper types have a negligible resistance to airflow, as they open fully in the airstream. We can provide actual figures upon request, based upon air velocity. The gravity flap damper has an increased resistance to to its mode of operation and, again, we can provide details of this upon request.

Constructional Specification


All dampers are constructed with a fully welded 2mm thick, galvanised steel outer casing, with integral flanges to facilitate fixing to the builders work opening or connecting ductwork. The blades are manufactured from galvanised steel or aluminium, according to type.

The bearings in which the blades run, consist of nylon brushes with shoulders into which are housed cadmium or zinc plated stub spindles (stainless steel spindles are used when the louvre or damper has only periodic use). The blade spindles are linked with zinc coated link arms and bars. Stainless steel side shims can be fitted as an extra between blade edge and casing for improved sealing where minimal leakages are required. Seals can also be fitted to the blades if required and to further improve the sealing properties.

The outer flanges are normally supplied undrilled unless otherwise requested and, where the louvres or dampers are sited externally, weather covers can be fitted over the spindle ends and motors for protection against prevailing weather conditions.

Alternative materials and methods of construction are available and details will be supplied upon request.



All damper types have a galvanised finish but can also be finish painted if required.

Actuator Details.


The dampers are available with a range of actuators, the most common being detailed below.

1 - 240 volt single phase A.C. motor offering powered opening / spring close operation.

2 - As 1, but with spring open/power close operation.

3 - As 1, but with 24 volt DC motor.

4 - As 2, but with 24 volt DC motor.

5 - 24 volt DC operated solenoid which offers snap shut actuation of the louvre or damper by utilising counter balance weights in the linkage mechanism and with this mode of operation being ideally suited for gas retention systems.

6 - Manual operation. An extended spindle with locking knob is fitted where manual operation of the louvre or damper is required.

Pneumatic or gas operated actuators are available where necessary and we would be pleased to submit further details upon request.

Dimensions and Fixing Details


The weatherlouvres and dampers can be supplied in virtually any size although, once the width by height dimensions of 2400mm x 2400mm are exceeded, then multi-section units are employed with connecting mullions.


For further information please contact CES at

Unit 5 Chancers Farm, Fossetts Lane, Fordham,

Colchester, Essex, CO6 3NY


tel 01206 240788


colchester engineering systems
colchester engineering systems
colchester engineering systems
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