603.6.2 Air connectors.
MC § 603.6.2
Air connectors are limited-use, flexible air ducts that are required to conform to other provisions applicable to air ducts and shall meet the following requirements: 1. Air connectors shall conform to the requirements for Class 0 or Class 1 connectors when tested and approved in accordance with UL 181.
2.Class 0 or Class 1 air connectors shall not be used for ducts containing air at temperatures in excess of 250°F (121.1°C).
3.Air connector runs shall not exceed 14 feet (4267.2 mm) in length.
4.Air connectors shall not penetrate any rated wall, partition, or shaft that is required to have a fire-resistance rating of 1 hour or more.
5.Air connectors shall not pass through floors.
