Vibration Monitoring for Air Handler Applications

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Monitoring the vibration of rotating components of enclosed air handling units presents a unique challenge for predictive maintenance programs. The air handling units are expected to maintain consistent environmental conditions, such as flow rate, temperature, and humidity, and often to extremely limited tolerances. In many laboratories, manufacturing, and warehousing spaces, small deviations in operating parameters can result in void products. As a result, opening a unit to access the rotating components to collect vibration data, or even to perform a visual inspection, is impractical because of the potential for ambient air to affect conditions or introduce contaminants.

Common faults with air handling units include:
▶ Unbalance
▶ Misalignment between the sheaves
▶ Looseness
▶ Belt resonance defects / worn belts
▶ Worn or damaged sheaves
▶ Bearing defects
▶ Rubbing
▶ Motor electrical, including rotor bar faults

Vibration Monitoring can be used on Air Handlers to:
▶ Reduce or eliminate exposure to safety hazards
▶ Reduce data collection time while increasing repeatability and data accuracy
▶ Collect data on previously inaccessible fan components
▶ Prevent high-cost failures
▶ Help ensure consistent environmental conditions

The first consideration is whether or not Process Monitoring or Dynamic Vibration Analysis is right for your condition monitoring program. Due to access concerns, permanent monitoring is the preferred method for repeatability, human safety, and operational effectiveness.

Process Monitoring requires 4-20mA Loop Power Sensors, which will provide the overall vibration level of the machine so that it can be trended and alarmed using the plant DCS, PLC, or SCADA system. Process monitoring will require permanently mounted loop power sensors that output a 4-20mA signal proportional to velocity or acceleration. Process monitoring will provide an allover understanding of machine health, but cannot provide the same level of detailed diagnostic data as Dynamic Vibration Analysis.

Dynamic Vibration Analysis allows for trended data and machine health diagnostics. However, Dynamic Vibration Sensors can be paired with CTC’s SC300 Series Signal Conditioners to create a hybrid approach for both Process Monitoring and Dynamic Analysis. A Signal Conditioner converts the signal from dynamic sensor into a 4-20mA output, so it can be tended and alarmed using the plant DCS, PLC, or SCADA system but also used for more in-depth predictive maintenance.

Regardless of whether or not a signal conditioner is the right choice for your program, CTC has a variety of accelerometers for use in air handler applications.

LOOP POWER SENSOR OFFERINGS FOR AIR HANDLER APPLICATIONS:
4-20mA monitoring will provide a cost-effective, online process monitoring solution. Our standard LP200 Series and LP300 Series can be permanently mounted for a 4-20mA output proportional to vibration in velocity or acceleration respectively. 

LP200 SERIES	LP300 SERIES
4-20mA Output Proportional to Vibration in Velocity	4-20mA Output Proportional to Vibration in Acceleration

CTC's Loop Power Sensors can be paired with our PMX enclosures to trigger alarm and shutdown.

RELAY AND PROTECTION EQUIPMENT FOR USE WITH LOOP POWER SENSORS:
CTC'S PMX Series Enclosure is a fiberglass, 1-4 channel process control enclosure with display and relay. These enclosures are designed for loop power sensor input and the relays can trigger alarm or shutdown.


GENERAL PURPOSE ACCELEROMETERS:
General Purpose Accelerometers typically meet the needs of air handling units. In limited access areas, like near belt guards, side exit connector accelerometers are typically suggested. CTC's Dynamic Vibration IEPE Ultrasound Sensors also provide an excellent solution for general-purpose monitoring with the ability for high-frequency fault detection. Some of our most popular General Purpose Accelerometers include:

AC102 & AC104	AC292 & AC294	UEB332 & UEA332
Multipurpose Accelerometer, 2 Pin Connector, 100 mV/g, ±10%, ±80 g, Dynamic Range	Premium Compact Accelerometer, 2 Pin Connector, 100 mV/g, ±5%, ±80 g, Dynamic Range	Dynamic Vibration IEPE Ultrasound Sensor, 1/4-28 Mounting, 2 Pin Mini-MIL Connector, 100 mV/g, ±10%, ±50 g, Peak

CABLES & CONNECTORS:
Due to the environment within the air handling unit, the cable connecting the accelerometer to the switch box needs to be robust, chemical resistant, moisture resistant, and reliable in a caustic environment, such as CTC's Premium V Series Viton™ Seal-Tight Boots or A Series Standard MIL-Style Connectors.

V SERIES VITON SEAL-TIGHT BOOT CONNECTORS	A SERIES MIL-STYLE CONNECTORS
V Series is a premium connector offering for the best chemical resistance and an IP69 rating for moisture concerns	A Series MIL-Style Connectors are a general-purpose offering that work in a variety of environments. The A Series comes with stainless steel locking ring and a variety of material options, including Polycarbonate, PPS, and Nylon.

JUNCTION BOXES
Junction Boxes can be used for local measurements or the transmission of data to online vibration monitoring systems. Junction Boxes can also be used for cable reduction purposes or for switched outputs during manual route data collection of the vibration signals. Depending on the environment in which your junction box is mounted, CTC offers the majority of our junction boxes in either fiberglass or stainless steel options.