What causes fan vibration?
Vibration occurs during fan operation and may have many causes, one of which would be imbalance. Other causes of vibration would include mechanical looseness, coupling misalignment, defective bearings, insufficient flatness of bearing mounting surfaces, rotor cracks, driver vibration and v-belt slippage.
What causes vibration in motor?
Vibration can be caused by one or more factors at any given time, the most common being imbalance, misalignment, wear and looseness. Misalignment /shaft runout – Vibration can result when machine shafts are out of line. Angular misalignment occurs when the axes of (for example) a motor and pump are not parallel.
What causes high axial vibration?
High axial readings generally indicate misalignment. The cause may be external, like coupling misalignment, or internal, like mechanical looseness or a bent shaft. Looseness may include a worn coupling, an oversized bearing housing, or with a sleeve bearing motor, excess bearing-to-shaft clearance.
How does vibration affect a fan?
Most fans are designed to operate below the critical speed, but if a fan is operated above the critical speed, the vibrations that occur while passing through the resonance band can lead to severe damage to bearings, seals, etc.
What is axial vibration?
Axial vibration is a kind of longitudinal shafting vibration which occurs in the crankshaft because of the radial as well as tangential forces.
What does vertical vibration mean?
VERTICAL Vibration (aka Tri-Planar, Vertical Uniform, Straight) How does the platform move? The platform moves straight up and down. Vertical vibration units tend to have platform motion with lower amplitude (about 2 – 4 mm) and often achieve comfortable frequencies (between 20 – 50 Hz).
What is the unit of vibration?
A complete assessment of exposure to vibration requires the measurement of vibration acceleration in meters per second squared (m/s2). Vibration exposure direction is also important and is measured in defined directions. The amount of exposure is determined by measuring acceleration in the units of m/s2.
What causes excessive vibration in a rotating fan?
Rotor Mass Unbalance. Rotor mass unbalance is the most common cause of excessive vibration in most rotating equipment and fans. The primary symptom of rotor mass unbalance is a high 1X vibration level.
What causes a fan to vibrate during a power outage?
Fig. 2. A difference in temperature between the top and bottom of a fan housing during outage or shutdown can be significant. Bowing in the shaft causes vibration on startup. The vibration is quite high at first and then decreases slowly as rotor temperature becomes uniform.
Why is my centrifugal fan making so much noise?
Loose mechanical connections between bearing caps, bearing pedestals or foundations can lead to excessive vibrations levels or exacerbate an existing imbalance problem. Looseness between the rotor shaft and fan shaft can also cause vibration.
What should the vibration level of a fan be?
Standards have been set as to what are acceptable vibration levels for corresponding operating speeds. Other sources that outline acceptable balance and vibration levels for fans include ANSI/AMCA 204-96, Balance Quality and Vibration Levels for Fans; ISO 14694:2003, and Industrial Fans; Specifications for Balance Quality and Vibration Levels.