Duct lining replacement

Why replace internal linings in a duct system?

• Often these linings (generally fibreglass) can be 25 or 30 years old, and have accumulated dust and dirt in the thickness of the lining - impossible to clean effectively.
• The facing on the fibreglass lining may have broken down, allowing the fibreglass to be exposed to the airflow causing delaminating of the fibres and for them to become airborne.
• In some instances the linings may have become damp which then provided the ideal conditions for the growth of fungi.
• If there has been a fire the linings will be impregnated with smoke and soot products.

What qualities would be required in a replacement lining?

• Because the original linings were installed to either prevent noise transmission or as a thermal insulator, then the replacement lining needs to have at least the same acoustic and thermal properties.
• The new lining needs to be flexible as it must now be installed through access openings in formed ducts.
• The lining should be fire and chemical resistant.
• The lining should have a surface suitable for future cleaning without damaging the lining.

Are there any other issues to be aware of?

• With the increasing questions about the possible adverse health aspects of fibreglass, Clean Air Management recommends that replacement linings should be a fibre-free product.
• It is important to keep the ducts under negative pressure while the old linings are removed to ensure full containment of the old fibreglass fibres.