Issue link: https://hi.iaq.net/i/650541
IAQA 18th Annual Meeting & Indoor Environment and Energy Expo (IE3) The views and opinions herein are those of the volunteer authors and may not reflect the views and opinions of IAQA. The information is offered in good faith and believed to be reliable but it is provided without warranty, expressed or implied, as to the merchantability, fitness for a particular purpose or any other matter. ACR, The NADCA Standard provides guidance on the following: Determining the need to clean Developing a clear scope of work & understanding of the cleaning project Protecting the safety of building occupants and prevention of cross-contamination during cleaning Proper cleaning procedures; and Quantifiable methods for verifying cleanliness at the end of the project. There are key cleaning requirements that HVAC system cleaning professionals must follow in order to clean to in accordance with ACR and other key industry standards. A. Cleaning to a Visibly Clean Standard According to ACR, The NADCA Standard, cleaning methods shall achieve a minimum level of visibly clean or the specified level of cleanliness verification defined in the scope of work. The scope of work outlines which components are to be included in the cleaning and which will not be included.An interior surface is considered visibly clean when it is free from "non-adhered" substances and debris. ACR, the NADCA Standard provides three methods for verifying cleanliness for HVAC cleaning projects. The three methods are 1) Visual Inspection, 2) Surface Comparison Test, and 3) NADCA Vacuum Test. The NADCA Vacuum Test provides a quantifiable method for verifying the level of cleanliness when visual inspection and surface comparison testing results are inconclusive or in dispute. B. Using Source Removal NADCA recommends source removal for proper HVAC system cleaning. "Source Removal" refers to the mechanical cleaning of system components to remove dirt and debris. Source removal methods employ vacuum units, compressed air, mechanical and hand brushes, and other tools to loosen dirt and debris and convey it to a containment device for proper disposal.Source removal requires two key elements to be effective. The first element is a means of agitating the dust and debris within the HVAC system. The second element is the extraction of contaminants from the HVAC system. Removal methods must be capable of removing the foreign material to the levels specified within industry standard. According to ACR, the NADCA Standard, all vacuum devices exhausting air inside the building shall be equipped with HEPA filters(minimum: 99.97% collection efficiency for 0.3-micron size).Vacuum devices exhausting air outside the facility shall be equipped with particulate collection including adequate filtration to contain debris removed from the HVAC system. Such devices shall exhaust in a manner that will not allow contaminants to re-enter the facility. C. Maintaining Negative Duct Pressurization Prior to and throughout the duration of the cleaning process, the HVAC system and associated air duct shall be kept at an appropriate negative pressure differential relative to the indoor non-work area. This negative pressure differential shall be maintained between the portion of the HVAC duct system being cleaned and surrounding indoor occupant spaces.Appropriate negative pressure implies enough negative pressure to satisfactorily prevent debris from entering the occupied space or leaving the contained area. D. Following Industry Standards for Creating and Closing Service Openings ACR, The NADCA Standard provides minimum requirements for service openings. Service openings shall not degrade the structural, thermal, or functional integrity of the system; shall not hinder, restrict, or alter the airflow within the air duct and shall not be made in flexible ductwork. Service openings shall be created in a