For proper operation, the speed settings must be the same. When the fans are operated at different speeds, problems occur. For example, when the exhaust is on high and the intake is on low, a partial vacuum is caused and it will be difficult to open watertight doors to gain entry to the space. Fans used in Navy ships in conjunction with supply and exhaust systems are divided into two general classes-axial flow and centrifugal. Most fans in duct systems are of the axial-flow type because they generally require less space for installation.
Centrifugal fans are generally preferred for exhaust systems that handle explosive or hot gases.
The motors of these fans, being outside the air stream, cannot ignite the explosive gases. The drive motors for centrifugal fans are subject to overheating to a lesser degree than are motors of vane-axial fans. Integrated Publishing's Official Web Page Click here for a current index of everything on this web site. All Rights Reserved.