HVAC Duct Construction Standards Metal and Flexible • Third Edition iii FOREWORD This Third Edition of the SMACNA commercial metal and flexible duct construction standards is another in a long line dating from the 1950s. A quick overview of the changes is provided in the front of this manual.
Standard McGill AirFlow single-wall flat oval duct and fittings are available in the dimensions shown in Table 5. 2. Some standard lengths of UNI-SEAL, flat oval duct are only available in 6-foot lengths; longer lengths are available on special order. Standard lengths of longitudinal seam duct are 5 and 6 feet.
Sizes: See table on back for available sizes. Contact CertainTeed for availability and minimum order quantities. INSTALLATION All duct liners must be installed in accordance with the requirements of the NAIMA Fibrous Glass Duct Liner Standards or SMACNA HVAC Duct Con struction Standards and the project speci˜ cation.
The system is 100% OSA, dual-duct and has approx 16,500 cfm at 60 deg supply air to the space. The new system will supply 20,000 cfm and possibly 52-54 deg air range. At that cfm, the lab will have about 1.5 cfm/SF and the duct velocity will be approx 4000 FPM. This is like a dust collection system.
Information Required for Duct Construction 1. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system. 2. The types of fittings to be used based on the designer's calculations of fitting losses (i.e., square versus 45 ° entry taps, conical versus straight taps, etc.).
3. High Velocity Duct Systems: High-velocity (HV) duct systems are characterized by air velocities in the range of 2500 to 3500 fpm. Low-velocity ductwork design is very important for energy efficiency in air distribution systems. Low-velocity design will lead to larger duct sizes, but it may be worth since, doubling of duct diameter