Chapter 5: Exhaust Systems, Mechanical Code
If individual units on a loop are in separate enclosed spaces, each unit must be sized to actual AWT for that unit. Talk Page Testing of Hot and Cold Mixing Dampers Each system that uses hot and cold mixing should be subject to the test so that a leakage factor can be determined.
Blank covers may be used for appearance if the capacity if not needed. Talk Page Pumps There are three pumps usually associated with an absorption system. It has been determined that when a hood is applied to any given outlet, the backpressure created by the hood causes the air to back up slightly. However, the air moving along a duct wall loses speed because of friction; consequently, the velocity in the center of the duct will always be greater assuming no special turbulent motion.
Make a final check of all pump and equipment data, and record. In general, for large flows at low heads, lower speed pumps 1,150 rpm or even 850 rpm will be most efficient.