Blade and louver assemblies for air-control dampers
Air-control damper components — blade motion and frame interfaces
Order the blade assembly against the damper it will fit. Specify the blade movement, axle supports and drive connection together, then check the assembly through its required travel in the receiving frame.
Moving blades, axles, crank arms, connecting linkage and bearings for air-control dampers, including assemblies supplied with a frame. Fixed weather louvers, automotive grille shutters and liquid-service valve trim have different requirements. Actuators and complete rated damper units require separately defined supply and performance boundaries.
Show how each blade turns and where its axle is supported
Greenheck distinguishes parallel action, with the blades rotating in the same direction, from opposed action, with adjacent blades rotating in opposite directions. Specify the required action on the assembly drawing so the crank arms and connecting linkage produce it. [1]
Greenheck’s catalogue shows formed-sheet and airfoil blade constructions, together with model-dependent bearing options. Use the receiving damper’s approved construction and bill of materials when ordering a replacement or subassembly. [1]
Record opening dimensions, axle spacing and mounting datums from the assembly drawing. State whether a frame, seals, drive shaft and linkage are included, or identify the existing parts to which the new assembly must fit.
Assembly feature
Detail to define on the interface drawing
Blades or louvers
Profile, span, section thickness, material and finish; show the blade layout and any differing blade widths or closure pieces.
Arm orientation, connection geometry and the travel envelope for the selected parallel or opposed action.
Bearings or bushings
Fit to the axle and receiving frame, retention, permitted movement and the specified environmental conditions.
02
Keep sealing contacts and linkage clearance intact in the installed frame
Greenheck identifies blade seals and jamb seals as different contacts in a low-leakage damper, and describes linkages concealed in the frame on its control dampers. Check the blade edges, blade ends and hidden linkage space as separate interfaces. [1]
Its installation manual warns that twisting, racking or misaligning the frame can increase leakage and operating torque. It also requires mounting screws to clear the blade linkage and directs handling through the frame or sleeve instead of the moving parts. [2]
Check the full blade sweep, end clearances and linkage motion after the frame is secured in the receiving opening. Include access for inspection and servicing, and protect the mechanism from construction debris and paint deposits. [2]
Specify any leakage acceptance for the complete assembled damper, with its test pressure, area basis, flow direction and seal configuration. A replacement blade’s dimensions or finish alone do not establish the assembled unit’s leakage performance.
List the temperatures and contaminants that affect blades, bearings and seals. Any fire, smoke or environmental-protection requirement needs evidence for the applicable complete assembly and its installation.
03
Select the operator from the assembled damper’s torque and control requirements
Belimo’s actuator-selection questions include damper area, blade action, seals, manufacturer torque, air velocity and static pressure. It also asks whether the actuator can couple directly to the shaft or requires additional linkage and mounting hardware. [3]
Give the operator supplier the drive-end drawing, direction of rotation, required end positions and mounting orientation. Agree the torque requirement under the actual air duty, including seal engagement and the linkage arrangement.
Define operating time, control signal, supply and any fail-safe action for the actuator being ordered. Include position indication or proof-of-position accessories if required by the control task. [3]
At handover, observe all blades through the complete commanded stroke and check the agreed end positions. Record any binding or incomplete travel and the actual operating conditions used for the functional test.
Keep the blade assembly’s mechanical movement record with the complete damper and actuator identification. Record its mass and lifting provisions with the installation details.
04
Air-damper blade assembly drawing notes
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Receiving damper: [model, frame/opening drawing, mounting orientation and supply boundary]
Blade field: [parallel/opposed action, profiles, spans, thicknesses, layout and materials/finish]
Axles and supports: [cross-sections, attachment, bearing locations, fits and retention]
Linkage: [crank arms, connecting members, drive end and unobstructed travel envelope]
Sealing: [blade/jamb contacts and complete-damper leakage test conditions]
Air duty: [velocity, pressure difference, temperature and contamination]
Operator interface: [torque requirement, end positions, operating time, control/fail-safe action and position feedback]
Delivery/acceptance: [included frame/seals/drive parts, functional travel test, mass and handling provisions]
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Share this page
Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 23 October 2026
Buyer questions
Do all the blades rotate in the same direction?
That depends on the specified action. Greenheck describes parallel blades turning in the same direction and opposed blades with adjacent blades turning in opposite directions. Show the required action and linkage geometry on the drawing. [1]
Can actuator torque be chosen from the blade area alone?
Belimo’s selection questions also address blade action, seals, the damper manufacturer’s torque requirement, airflow conditions and shaft coupling. Supply those details with the blade area when selecting the operator. [3]
Sources and evidence scope
Sources checked 2026-10-23T12:05:50+08:00. Greenheck documents complete control dampers and their moving parts and installation interfaces. Belimo addresses actuator selection; its guidance does not assign a universal rating to a blade subassembly.
