Particularly suited to waste gas ducts on bagasse or black liquor plants or where gas contains fibrous particulate which could get caught up on butterfly or louvre damper blades.

These are primarily intended as fan inlet control dampers where, by introducing swirl into the inlet of the fan in the direction of rotation, the fan curve is changed as the damper moves, thus maintaining operation at an efficient point on the fan curve and eliminating the possibility of stalling at low volumes. The dampers can be designed to suit overhung impellers or impellers with through shafts and can be built for double inlet fans and operated by a single drive mechanism. Materials of construction and drive configurations are selected and designed to suit the application and customer requirements

The variations possible for these dampers are virtually infinite. All types can be manufactured as either “open / close” or as control dampers, and in the case of diverter dampers, the blades may be linked and operated by a single actuator or they may be operated individually. Dilution dampers could be of the flap type round or rectangular, and with resilient seats or rectangular louver construction with special seal arrangement to reduce indraught air leakage. Swing dampers provide a means of keeping the blade out of the gas stream when in the open position and are particularly suitable for cases where the gas stream contains abrasive particulate. Materials of construction and drive configurations are selected and designed to suit the application and customer requirements.

Louver Dampers can be manufactured circular or rectangular, and in a variety of configurations. Generally, multi-blade louver dampers are used as control dampers – or as isolation dampers in rectangular or square ducts of a large cross sectional area, where use of a single blade would be impractical. Due to the multiple blade arrangement, sealing efficiencies are lower than in single blade butterfly dampers. However, by placing two louver dampers adjacent to each other and purging the cavity between the two sets of blades when closed, with air at a higher pressure than the system pressure, total isolation of process gas may be achieved. When used as control dampers, the blades are normally arranged to counter rotate, this provides very good control characteristics through the…

These can be manufactured circular or rectangular, in a variety of configurations to suit a multitude of applications. Although mainly used for isolation, they can be used for control. Sealing arrangements range from “swing through” for control only to stainless steel flexible blade seals for isolation efficiencies greater than 99% sealing efficiency. Bearings can be mounted inboard or outboard, depending on the application, and will generally be of the maintenance free type. Dampers can be manufactured in a variety of materials and can be supplied with refractory lining if required. Applications range from simple isolation dampers at ambient temperatures with manual lever arm operation to control dampers at temperatures as high as 2000°C (water cooled casing and blade). Actuation can be arranged to suit customers…