Duct Static Working Pressures

As a result of efficient nozzle design, Twa MAC Beams optimize air turnover within the space, and require less primary air. Also known as "induction diffusers", Twa MAC Beams can create a higher induction effect and consequently a greater total capacity with duct static pressures in the range of (0.5"-1"w.c); without generating excessive noise (NC18-NC26). Some manufacturers prefer lower operating static pressures, because their nozzle design requires too much primary air and their beams generate too much noise to justify their use at higher pressures. However, the superior capacity benefit of a high induction ratio is lost at these lower duct static pressures.

Twa MAC Beams can operate with as little as 0.3" w.c. and can yield up to a 6:1 induction ratio. This allows the ventilation system to provide the least amount of outside air processing for the highest secondary cooling/heating capacity. Although fan energy is increased slightly, the increase in beam capacity generally offsets the effect.

Secondary cooling capacity of a 2'x4' Twa MAC Beam at 18 degrees F approach. Next...