Sensors Midwest 2017

Most mechanical and evaporative heat rejection equipment in an HVAC system has an induced-draft configuration typically including one or more axial fans mounted at the top of a steel structure. The fans move outdoor air through the equipment in order to expedite the heat transfer process. Because axial fans are large-diameter propeller fans with long blades, their stable performance is easily influenced by mechanical or environmental imbalance, damaged or worn gears and damaged shaft/coupling. When not at a stable operating level, the fans tend to vibrate at increased amplitude. Vibration monitoring is essential to provide signals for early warning or provide shutdown when vibration levels exceed a predetermined threshold.