First: "220V Cooling Fan" in the intensive care unit of work must be considered noise, and you should try to consider to select large size. Low noise, oil-bearing.
Second: the power supply cooling fan working on the locomotive must consider the temperature rise of the environment, life, vibration should be selected to meet the ball in the case of shock, but in the case of vibration should try to use oil bearing in order to meet the requirements for reliability .
Third: "220V Cooling Fan" in communication cabinets work must consider the supply voltage and the dust in the environment, temperature, service life, then should make full use of ball bearing cooling fans.
Fourth: "220V Cooling Fan" in a clean work environment must take into account the amount of dust, dust produced mainly fan of the Division and the volatile bearing lubricant, then a small amount of oil should be selected ball, while meeting under the circumstances to minimize the amount of wind speed.