First set operations environment: within the rated voltage, room temperature 25 ℃ or so, relative humidity 15% ~ 65% RH hydraulic bearing professional work environment assessment: low accuracy expected life: 40000 hours, the total for 1666. 7 days, which is about 4. 5 years careful description: oil layer of fan is mainly containing oil, belongs to the sliding friction. Once the oil cost after the cooling effect is very poor, speed significantly reduced, and noise. This fan is a relatively short life, and its price is proportional to the money, but a new generation of hydraulic bearing oil after the filling technology, utilizing life has larger ascension, basically can be more than 3 w hours, once can satisfy most application needs. Double ball bearing professional evaluation: high precision expected life: 50000 hours, the total is 2084 days, about 5. 7 years of meticulous desciption: bearing and shaft relative motion as point contact, less friction, adopt internal ball bearing under adhere to implement positioning with smooth oil rotary motion; Fan in any fixed direction, the double ball fan advantages are long life, anti-aging performance is good, audit high speed fan, double ball bearing defect is the formation of the high, and the noise is bigger under the same degree of speed.