Which of these tapes is acceptable as a closure system for fibrous glass duct board?

The correct choice of tape as a closure system for fibrous glass duct board is pressure-sensitive tape labeled UL181. This is because UL181 is a standard that outlines the performance criteria for the tapes used in sealing and joining duct systems. Tapes that are labeled UL181 have been tested and certified for various qualities, including adherence, durability, and resistance to the conditions typically encountered within HVAC systems. This ensures that they provide a reliable and effective seal, which is critical in maintaining the efficiency and safety of the duct system.

Other types of tape, such as electrical tape, duct tape, and masking tape, do not meet the rigorous standards outlined by UL181. They may not provide the needed adhesion or resistance to temperature and humidity that is essential for proper sealing in duct systems. Using a tape that does not meet these requirements can lead to leaks, reduced efficiency, and potential health issues from air quality problems. Thus, pressure-sensitive tape labeled UL181 is the only appropriate choice for ensuring the integrity and performance of fibrous glass duct board installations.