C. Doctor india is an iso 9001: 2000 certified company manufacturing centrifugal fans, axial fans, jet fans, shell & tube heat exchangers, finned tube coolers & heaters, steam coil air preheaters etc. Doctaire bag filters are designed to control air pollution in the industries where dust is generated during manufacturing process. Doctaire bag filters are designed for high degree of dust separation, constantly adopting them to the latest technological standard. All designs are completely enclosed in a steel structure body.