RMS-LB 2018 with 12/20 Revisions

ASD (revised 12/20) 27 ANSI/AARST RMS-LB 2018 (with 1220 revisions) Radon Mitigation Standards for Schools and Large Buildings 6.4.12 Horizontal trajectory While it is best practice to avoid horizontal trajectories, 90 degree horizontal exhaust trajectories are permitted if compliant with all other distances required in Section 6.4 and Section 6.4.12.1 or Section 6.4.12.2 . 6.4.12.1 90-Degree Horizontal Discharges If passing the edge of the roof, the point of exhaust for a 90-Degree horizontal discharge shall not be less than 20 feet (7.5 m) above grade nearest to the point of exhaust. The point of exhaust shall comply with Section 6.4.3 Directional spread including for distances above the breathing space where individuals congregate or traverse as stipulated in Section 6.4.7 . Where “T” style rain caps are configured for 90-Degree horizontal discharge in two directions, both discharge trajectories shall meet these requirements. Informative advisory —Exhausts at a 90-degree angle are prone to form icicles during freezing weather that can fall to cause harm to property or individuals. 6.4.12.2 Rain Caps The point of exhaust for diffused horizontal discharges shall not be less than 15 feet (4.6 m) above grade nearest to the point of exhaust and not less than 4 feet (120 cm) above or 15 feet (4.6 m) away from operable openings into the structures, such as windows, skylights and doors. 6.4.13 Increased distances for large capacity systems When the ASD system is designed for larger airflow capacities with duct piping larger than 4-inch (100-mm), distances shall be increased beyond what is required in Section 6.4 to comply with Table 6.4.13 . Table 7.4.13 Pipe ID As in Section 6.4 3”- 4” Pipe (10 cm) Distance Away Distance Away Distance Above, Below or To Side Directional spread As in Section 6.4.3 10 ft (3 m) Straight-line As in Section 6.4.4 20 ft (6 m) Grade, Operable Openings and People Sections 6.4.5, 6.4.6 and 6.4.7 For Larger Pipe ID Increase to Increase to Increase by 6” (15 cm) 12 ft (3.6 m) 25 ft (7.6 m) 2 ft (1.8 m) 8” (20 cm) 18 ft (5.5 m) 30 ft (9 m) 4 ft (2.4 m) 10” (25 cm) 20 ft (6 m) 40 ft (12 m) 6 ft (1.8 m) For pipe larger than 10” (25 cm) Shall be increased to meet or exceed ASHRAE 62.1 2016, Appendix B, Separation of Exhaust Outlets and Outdoor Air Intakes