• Mashine Dezign & Mfg

Rotary Air Lock Feeders

Rotary air lock feeders (RAFs) are used to feed material at a controlled rate (metering) while maintaining an air lock between the up and down stream. Feeders used for metering do not require an air lock, whereas feeders operating under differential pressures have very close tolerances between the rotor and stator, which effectively maintain the air lock. The RAF design centres around characteristics of material handled and its application requirements, depending on which, various configurations and combinations are possible. The rotor can be open, closed, semi-closed with deep pockets, scalloped, flex tips (adjustable) and other different styles depending upon the application. The body can be 'drop through' (inlet and outlet openings inline), 'blow through' (provided with pipe connections for pneumatic conveying application), 'offset' or 'side entry' (with offset inlet and outlet opening centres). Air leakage rates of different models vary according to the application (pressure differentials, temperature, flow resistance etc.) And RAFs can be designed to suitably meet the flow leakage criteria of process requirements. The material of construction can be mild steel, carbon steel, stainless steel in combination with various other ferrous/non-ferrous metals. The body/rotor can also be provided special coatings/lining such as hard-chrome/tungsten carbide, etc., and with internally fitted sleeves/liners of special materials (for high abrasion, corrosion applications). Various options such as body vent, seal air-purging, material deflectors, special shaped flanges to match preceeding and succeeding equipments, direct drive, flame proof versions, sheared inlet, etc, can be provided. Apart from theoretical calculations, the RAF design involves several permutations and combinations in every stage keeping into view application and process parameters. RAFs are custom-built to suit a variety of requirements including high pressure and temperature applications.