Construction and Operating Principle of Centrifugal Explosion-Proof Fans

Construction and Operating Principle of Centrifugal Explosion-Proof Fans

Centrifugal explosion-proof fans typically consist of an inlet, an impeller, a volute and guide vanes. The structure of a centrifugal explosion-proof fan comprises a component that operates within the air stream, consisting of a rear disc, a hub sandwiched between the discs, and blades mounted on the hub. Air flows along the channels between the blades. At the impeller outlet, the angle between the relative air velocity W2 and the circumferential velocity U2 is known as the blade outlet angle, denoted by β2. Based on the magnitude of the outlet angle β2, centrifugal explosion-proof fans can be classified into forward-curved (β2 > 90°), radial (β2 = 90°) and backward-curved (β2 < 90°) types. Most mining-grade centrifugal explosion-proof fans are backward-curved. There are two types of inlets: single-suction and double-suction. Under identical conditions, the width of the blades (impeller) in a double-suction fan is twice that of a single-suction fan. Centrifugal explosion-proof fans are fitted with a guide vane assembly between the inlet and the impeller (some fans do not have a guide vane assembly) to pre-direct the airflow entering the impeller, thereby achieving performance regulation.