Because high pressure air is relatively costly, it usually is less expensive to use a blower if the air requirements are continuous. However, for occasional use or where excess compressed air is already available, Air-Ductors are initially less costly and very easy to install.
The Selection Table shows the approximate volume of lowpressure air (1 psig) that various sizes of Air-Ductors will deliver. It also shows the high-pressure air orifice size to be used with various inlet air pressures. When operating at capacities shown and 1 psig delivery pressure, about 25 – 35% of the total delivered air will be high-pressure air (measured on a free basis). See pages 2 and 3 for capacity of high-pressure air orifices. At lower delivery pressures, the ratio of high-pressure air will be less than indicated above.
Air-Ductors are particularly useful for supplying the combustion air requirements of a single Flomixer or group of burners. No valves or blast gates should be used between the Air-Ductor and the Mixer or Mixers it is supplying. If volume controls, either manual or automatic, are required, they should be placed in the high-pressure air supply.
Air-Ductor Assemblies include Hijector, valve, gauge (0 – 30 psig standard), and expanding coupling on outlet end of Hijector, which determines the outlet pipe size to use.