Duct cleaning sample specification

Specialist

The duct cleaning is to be carried out by a firm specialising in this type of work and who can demonstrate previous successful projects of this nature. All work is to be carried out to USEPA and NADCA recommendations.

USEPA - United States Environmental Protection Agency

NADCA - National Air Duct Cleaners Association Inc (US).

Source removal

All existing air conditioning and ventilation ducts are to be internally cleaned by the source removal method, which is to remove all dust, dirt and other pollutants from the airway. During duct cleaning a negative pressure must be maintained at all times on the duct system by the connection of a vacuum collection unit which will prevent the migration of dust, dirt and contaminants into the building.

In conjunction with the negative pressure unit, source removal is to be accomplished by gen­tle, well controlled brushing of all internal duct surfaces.

Sanitizing

On completion of the source removal, all interior duct surfaces are to be washed with a deter­gent / disinfectant, and then all ducts are to be fogged with an approved biocide.

Air changes

On completion of duct cleaning, the ventilation system is to be run for at least 8 air changes before occupancy.

Duct components

The duct cleaning is to include all duct mounted components such as turning vanes, dampers, fans, silencers, grilles and diffusers, but does not include the repair of faulty componentry which should be brought to the attention of the engineer.

Air handling unit

Each AHU is to be thoroughly cleaned, and is to include all interior surfaces, coils, condensate trays, fan and drive.

Duct mounted coils

If only moderately dirty then these should be thoroughly vacuum cleaned. Clogged coils should be sprayed with an approved non-toxic chemical to loosen dirt and then all dirt and moisture vacuumed clean. Coils should be properly rinsed and dried.

Fibreglass linings

These are to be lightly vacuumed only without damaging the facing of the lining. Where minor delaminating of the lining is found, this is to be repaired by the application of a suitable bind­ing agent. Where delaminating is severe the engineer is to be advised.

Where the fibreglass lining is cut for access etc, then the raw edges are to be sealed with a binder to prevent delaminating.

HEPA filters

All vacuuming equipment is to incorporate HEPA filters.

Access panels

Quick release, pressed steel, insulated access panels are to be installed by the duct cleaning contractor where required and their location subsequently shown on the as built documenta­tion.

Validation testing

Immediately following completion of the duct cleaning work a NADCA vacuum test is to be performed on each system cleaned to validate the duct cleaning work.

Report

On completion of the duct cleaning work a maintenance report shall be submitted detailing areas cleaned and any chemicals used.

Encapsulation

Duct cleaning which relies only on a high velocity airflow through the ducts will not be per- miffed. Likewise the use of sealants to encapsulate dirt in the ducts will not be permitted. The system fan or AHU is not to be used during the cleaning, or as an air movement device for the cleaning process.