The installation position of three types of air filters?

Air filter is a kind of absorption and intercept air dust and suspended solids from the device, its volume is very small. Can be applied to large air flow ventilation system, pharmacy, hospital, food, clean room, such as air filtration system, filter has big filter area, large dust content, low resistance, long service life, wide applicable scope, etc. So where is the three different kinds of air filter installation? one Coarse efficiency filters should be installed in the fresh air after chukou air handling unit, or fresh air and return air mixing section, before the air preheater, to prevent the preheater surface dust, reduce the heat transfer effect. 2. In the blower chukou positive pressure setup efficient filter, prevent untreated air into the air handling unit, pollution of the clean air filter through. 3. Clean room air supply outlet filter set * * * * * * and guarantee level 3 filtered clean air will no longer be pollution.