Radial fan casings made from extrusion - blown plastics pref with vacuum assistance

摘要

Cylindrical casings developed in a spiral to provide a tangential exhaust outlet are more easily formed by (vacuum assisted) blow moulding than by fabrication from sheet materials. Pref. at least one casing and wall is moulded integrally with the casing - normally the second end is also formed but cut off to allow the fan rotor and/or a (detachable) end cover to be fitted.