Type 13 double H-rail suspension has great flexibility, making it ideal for high ceilings, larger diameter ducts and frequent laundry.
Exposed exterior hoops are used in conjunction with a double H-rail system. The exposed hoops are made of anodized aluminum and help keep the H-rails from "cheating" toward the center of the duct when there is no airflow. This type of suspension is primarily used for larger ducts that need to be washed on a regular basis, such as in meat processing plants. The H-rails allow the duct to be easily removed and re-installed to reduce the amount of labor and down-time associated with maintenance. Suspension types available with exposed hoops are shown below.