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Manufacturers of Air Diffusion Products Since 1969

Pressure Relief Dampers

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Strong, durable and effective

Our multi-leaf pressure relief damper units – Type MLD – swing open when the air pressure exceeds a certain limit to allow air to be discharged.

The pressure relief dampers consist of a single set of horizontal light gauge plastic flaps mounted on stainless steel axles, which pivot about their top edge.

Manufactured in the UK, our pressure relief dampers combine the strength of steel with the durability of plastic.

Benefits of FNW pressure relief dampers:

  • Range of sizes – Type MLD is produced in standard sizes of 50mm increments from 150 x 150mm up to 1000 x 1000mm inclusive
  • Bespoke products available – dampers can be produced in any intermediate size of height or length.
  • Different colours available – black or white
  • Corrosion protection – the damper is manufactured in zinc coated steel and polyester powder coated prior to assembly. Also available in stainless steel for enhanced corrosion protection
  • Accommodating – dampers can be supplied without fixing flanges, with the damper mounted in a channel frame for securing inside the duct or opening
  • Universal – dampers may be fitted in a unit with any return air grille or louvre with the grille casing being extended to accommodate the pivoting flaps
  • Flexible – if dampers are fitted within an internal wall or partition, the spigot depth can be reduced and a matching rear loose flange provided for fitting to the rear of the opening
  • Adaptable for external walls – if fitted to an external wall a cowl or external louvre should be fitted to minimise the effects of wind pressure.

If you’d like to know more about FNW Engineering and our range of British made grilles and air diffusion products then call 01484 861233 or complete our online contact form.

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Made in England


ALL Air diffusion products supplied by FNW are manufactured at our West Yorkshire premises by our skilled staff and engineers.

Contact Us

FNW Engineering Developments Ltd.
New Street

Tel: 01484 861233 Fax: 01484 864928


FNW Engineering Developments Ltd - Tel: 01484 861 233 - Fax: 01484 864 928 - Copyright © FNW Engineering Developments Ltd