Outdoor airvolume5/2/2023 ![]() ![]() Hurricane louvers are designed to be used in locations subjected to extreme weather conditions from hurricanes or tropical storms where the louvers may be subjected to high-velocity debris. Other parts of the country, especially throughout the South where hurricanes are common, may require hurricane louvers or wind-driven rain louvers. With these considerations implemented in the design, rarely are there rain intrusion or water leakage problems in outdoor air intake systems. As an extra measure of precaution and good practice, the first 10 feet of outdoor air duct beyond the plenum should be sloped back toward the plenum and sealed watertight. The outdoor air plenum should be provided with a bottom sloping to the outdoors or provided with a drain to relieve any splashing water that makes its way through the louver. Looking at a typical water penetration rated stationary louver with drainable blades, it is found that the required air velocity for the beginning point of water penetration can typically be above 900 fpm through the free area, so a commonly used selection point of 500 fpm is relatively conservative with respect to water penetration. Louvers are typically selected at a maximum of 500 feet per minute airflow velocity through the louver free area. Selection of louvers in the Midwest, for example, is usually based on preventing water penetration through the louver due to rain falling on its face. Once a louver has been tested and the accuracy of its ratings proven, the manufacturer can display the test results, along with an image of the AMCA seal that corresponds to the testing in its literature. ![]() These tests are conducted at an AMCA-accredited laboratory. Most recently published in 2015, ANSI/AMCA Standard 500-L is the standard to which louvers are tested and its test protocols are what the AMCA certified rating program uses to certify a louver’s performance.ĪNSI/AMCA Standard 500-L covers five testing protocols: pressure drop, airflow leakage, water penetration, wind-driven rain penetration and wind-driven sand penetration. ANSI/AMCA Standard 500-L: Laboratory Methods of Testing Louvers for Rating defines test procedures for certifying louvers. Air handling louvers are designed to protect air-intake openings from the infiltration of unwanted water while allowing air to pass into the system, with different louver models offering different levels of performance. ![]()
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