Weathering By Dan Rau SENIOR ENGINEERING MANAGER, RUSKIN the Storm with AMCA 550 L ouvers protect air intake and exhaust openings in buildings and equipment from the infiltration of rain. Water that passes the outer shell of the building can damage interior building finishes and can also result in mold growth. Louvers come with many varieties of components to help collect rain water and funnel it to the outside of the building shell. Air Movement and Control Association (AMCA) International, the trade association for louver manufacturers, offers a certified ratings program that uses various ANSI-accredited AMCA test standards to determine the ability of louvers to eliminate water from the incoming air stream. In 2007, AMCA published Standard 550 Test Method for High Velocity Wind Driven Rain Resistant Louvers to rate water performance in hurricane-type events. AMCA 550 was adopted by the International Mechanical Code and Florida Mechanical Code as the performance standard for louvers in hurricane prone areas. To help ensure building protection and code compliance, this article describes ANSI/AMCA 550 and when it is required. Louver Water Tests – Overview Most louvers are rated to ANSI/ AMCA 500L for still-air water penetration. This test evaluates when water will be pulled into a louver by system intake velocities. ANSI/AMCA 500L also establishes procedures for a wind-driven rain tests, which subject louvers to system-intake velocities in combination with wind velocities of 29 mph with a rainfall rate of 3-in./hr, or, Figure 1 – AMCA 550 test setup. Image courtesy of AMCA International. Hood Deflector 610 mm (2 ft) Min. Lintel or CMU Water Spray Nozzles Louver 610 mm (2 ft) Min. Plastic Film (typical 3 sides) Wind and Water CMU 3.05 m (10 ft) Maximum Channel Bucket 3.36 m (11 ft) Maximum Wind Generator Discharge Plane w w w. a m c a . o r g AMCA I n t e r nat i o na l inmotion Fa l l 2 0 1 3 13http://WWW.AMCA.ORG