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The Sheet Metal and Air Conditioning Contractors' National Association (SMACNA; pronounced 'Smack'-'Nah') is an international trade association with more than 4,500 contributing contractor members [1] in 103 chapters [2] throughout the United States, Canada, Australia and Brazil. Its headquarters is in Chantilly, Virginia.
Process duct work conveys large volumes of hot, dusty air from processing equipment to mills, baghouses to other process equipment. Process duct work may be round or rectangular. Although round duct work costs more to fabricate than rectangular duct work, it requires fewer stiffeners and is favored in many applications over rectangular ductwork.
Duct leakage testing. A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating, ventilating and air-conditioning (HVAC) ductwork. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow.
Round duct is made using a continuous spiral forming machine which can make round duct in nearly any diameter when using the right forming die and to any length to suit, but the most common stock sizes range evenly from 4" to 24" (10-60 cm) with 6"-12" (15-30 cm) being most commonly used. Stock pipe is usually sold in 10' (300 cm) joints.
Smoke exhaust ductwork, in Europe, is typically protected via passive fire protection means, subject to fire testing (typically to NBN EN 1366-8 [1]) and listing and approval use and compliance. It is used to remove smoke from buildings, ships or offshore structures to enable emergency evacuation as well as improved firefighting.
The ductwork airtightness level is the airflow rate through ductwork leakages divided by the ductwork area. It is recommended to test at least 10% and 10 m 2 of the duct surface including all duct types and a variety of sizes and components. The ductwork surface area is estimated according to EN 14239. [11]
Turning vanes inside of large ductwork. Turning vane close-up. HVAC turning vanes are sheet metal devices inside of mechanical ductwork used to smoothly direct air inside a duct where there is a change in direction, by reducing resistance and turbulence.
Duct leakage testing of forced air heating/cooling systems - both supply (vents) ducts and return ducts can be tested to determine if and how much they leak air. A duct test can be combined with a blower door test to measure the total leakage to outside, measuring effective leakage to the outside of the house only.