"AC Fan" is to rely on the effect brought gears, gear lubrication better if the fan, then you can play a good supporting role in the use of fans, but the rotation of the gear will produce a lot of noise, Roots blower per revolution, you need three exhaust suction phenomenon occurs, the process carried out in the exhaust noise produced naturally, so in dealing with Roots blower noise problems still need a little look. Since fuel consumption rotary blower is relatively large, there will be oil and gas produced in the exhaust port, which would generate a lot of pollution, and rotary blowers in the case of lack of oil will produce a lot of wear and tear, this has the effect of wind turbines for use big impact, coupled with rotary blowers in use, the noise is relatively large, so in many cases, users will not choose this type of blower.