Revised HVAC cleaning procedures distribution, January 2003

NYC 9/11 Public Portal Document

Encapsulant coatings shall be for specific use in ventilation systems and applied per manufacturer's instructions including safety instructions. Encapsulant coatings shall be applied directly to the interior porous surfaces of AC/ventilation system components by hand brushing, rolling, or troweling, or via spray system, with a maximum distance of 24" from the spray discharge tip to the surface being treated. Encapsulant coatings may not be fogged into the system. A continuous film thickness should be achieved in treated areas, as per manufacturer's instructions. Encapsulants shall be water-based, with low VOC (volatile organic compound) emissions, and meet NFPA smoke development and flame spread requirements for ventilation system products. Encapsulant coatings shall be applied in accordance with applicable federal, state, or local regulations regarding the use of such products and MSDS copies for any encapsulant products used in the AC/ventilation system shall be available on-site.

Areas of damaged interior AC/ventilation system fan unit or duct insulation that is abraded or delaminated such that application of an encapsulant coating would be inappropriate as determined by the NADCA-certified ASCS should be removed in consultation with building management. Replacement of such insulation with an appropriate material shall be the responsibility of building management.

Procedures

1. Identify the system to be cleaned including outside air intake, fan unit, supply ducts and return ducts if appropriate.

2. Determine how the system will be segregated for cleaning; typically the fan unit will be cleaned separately from the ductwork unless the ductwork consists of very short runs on the same floor. As a general procedure, cleaning work should follow the ventilation system air flow. Cleaning should start at the outside air intake or return ducts, proceed to the air handling unit, and then proceed through the supply side of the air distribution system to the supply air diffusers.

3. Lock out and tag out the fan unit. Note that the NYFD needs to be contacted to determine permitting procedures if there are in-duct smoke detectors as these need to be disabled for duct cleaning.

4. Attach a local capture, HEPA filtered, Air Filtration Device (AFD) or vacuum collection system to the lowest opening of a riser or the fiirthest point of a horizontal duct, to place the system under negative pressure. Sufficient negative pressure shall be maintained to prevent the dispersion of dust outside of the duct. Isolation/zone pillows shall be used as necessary to isolate sections of the system, so that sufficient negative pressure is maintained in each work zone.

5. Exhaust the AFD or vacuum collection system to the outdoors through a window. If no window is available, a stairwell may be appropriate. Alternately, two AFD’s or vacuum collection systems may be connected in series so that a second unit filters the exhaust air from the first. Another method of ensuring that air contaminants do not leak through an air cleaning device is through in-place leak testing of the filtration component using DOP testing.

6. Cover all open supply air grilles, supply diffusers, and return air grilles located in the affected ductwork using fire-retardant polyethylene sheeting or bags and duct tape.

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