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

Pressure-sensitive tape labeled UL181 is considered the appropriate choice for a closure system for fibrous glass ductboard due to its specific design and testing for applications in HVAC duct systems. UL181 is a standard that ensures the tape can withstand the conditions related to air ducts, such as varying temperatures, moisture, and airflow pressure. This tape is formulated to create a reliable and durable seal, effectively minimizing air leaks, which is crucial for maintaining system efficiency and performance.

In contrast, masking tape and electrical tape do not have the same specifications and durability required for duct sealing applications. Masking tape is primarily designed for temporary adhesion in painting and crafting, while electrical tape is intended for insulating electrical wires rather than for sealing ductwork. While duct tape may appear to be a suitable alternative due to its strong adhesive properties, it often lacks the necessary testing and certification for use in HVAC systems, which can lead to potential failures in sealing integrity over time. Thus, pressure-sensitive tape labeled UL181 is the reliable choice for ensuring proper closure of fibrous glass ductboard.