Centrifugal fans will vibrate during operation, and the vibration frequencies generated according to different situations are different, and the vibration value standards of different specifications of equipment are also different.
1)Centrifugal fans are classified according to the vibration frequency range
According to the vibration frequency range, centrifugal fans can be mainly divided into low frequency vibration, medium frequency vibration and high frequency vibration:
1. Low frequency vibration: f<10Hz (n<600 rpm). In the low frequency range, the vibration intensity is proportional to the displacement.
2. Medium frequency vibration: f=10~1000Hz (n=600~60000 rpm). In the mid-frequency range, the vibration intensity is proportional to the speed
3. High frequency vibration: f>1000Hz (n>60000 rpm). In the high frequency range, the vibration intensity is proportional to the acceleration.
Taking the amplitude as the vibration standard, the amplitude can reflect the magnitude of the vibration amplitude. Taking the vibration speed as the vibration standard, the vibration speed can reflect the magnitude of the energy. Taking the acceleration as the vibration standard, the vibration acceleration can reflect the magnitude of the impact force. For most equipment, a more suitable diagnostic parameter is speed, because it is an ideal parameter to reflect vibration intensity, so many vibration diagnostic standards use the effective value of speed as a discriminant parameter.
2) Standard of vibration value of centrifugal fan
1. Vibration identification specification of general centrifugal fan and axial fan exhaust fan (JBTQ334-87) ≤5.0Mm/s is excellent, ≤6.3mm/s is up to standard.
2. Vibration identification specification for large and medium centrifugal fans and axial fans blower motors (JB/TQ433-85) ≤1.5 mm/s is excellent, ≤2.8 mm/s is acceptable, and ≤4.5 mm/s is weak.
3. The allowable vibration value of the axial flow fan (double vibration amplitude) (mm) is 0.05, the instantaneous speed (mm/s2) is less than or equal to 9.8, and the instantaneous speed specified value table when the motor is running is 39.8 ~ 39.2 is excellent, and 0.12≧39.2 is abnormal.
3)centrifugal fan vibration speed value standard
1. When the bearing vibration speed is effectively displayed: 11mm/s.
2. When displayed with bearing amplitude, it is the following value:
(1) When the synchronous speed of the motor is 3000 rpm: the upper limit allowable value is: 0.1mm (double amplitude);
(2) When the synchronous speed of the motor is 1500 rpm: the upper limit allowable value is: 0.2mm (double amplitude);
(3) When the synchronous speed of the motor is 1000 rpm: the upper limit allowable value is: 0.31mm (double amplitude);
(4) When the synchronous speed of the motor is 750 rpm: the upper limit allowable value is: 0.4mm (double amplitude);
(5) When the synchronous speed of the motor is 600 rpm: the upper limit allowable value is: 0.5mm (double amplitude);
(6) When the synchronous speed of the motor is 500 rpm: the upper limit allowable value is: 0.6mm (double amplitude).
It can be seen from the above introduction that the vibration classification of centrifugal fans can be mainly divided into low-frequency vibration, medium-frequency vibration and high-frequency vibration according to the vibration frequency range.
