Types of Axial Flow Fans
Textile Humidification Fans
Types of Axial FLow Fans

1200 mm dia fan for Textile Mill Humidifiers against technical specifications provided by ATIRA, Ahmedabad.

Raw Materials - The necessary raw materials for the fan impellers include glass fibre in various forms like chopped strand mat, roving, woven roving, cloth surface mat and resin (vinyl ester & polyester), catalysts, accelerator, hardener, pigments, surface treatment agents etc. All the raw materials are available indigenously.

FRP Blades - The process called Resin Transfer Moulding (RTM) has been used to fabricate these fan blades. This is a low-pressure, closed mould semi-mechanized process.
 
The fibre reinforcement, which may be pre-shaped is placed in the required arrangement in the cavity of a closed mould and a liquid resin of low viscosity is injected under pressure into the cavity, which is subsequently cured. After curing, the material is cooled in the atmospheric temperature and is subsequently placed in the electrically heated oven for post curing, if necessary. The main potential advantages of RTM can be summarized as the capability of rapid manufacture of large, complex, high-performance structures with good surface finish on both sides.

The Hub - The hub consists of four main parts viz. cast iron bush, aluminum block, supporting plates and hardware items such as nuts & bolts. The cast iron bush and aluminum blocks are manufactured by sand moulding and machined as per the required drawings. The four components are then assembled together and tested for static & dynamic balancing.

Fan Assembly - Apart from optimally designed impellers, an axial flow fan also comprises other critical components such as fan hub, support plates, fasteners, bushes for fixing the drive shaft etc. The FRP fan blades and the hub are assembled together & are again subjected to static & dynamic balance test and inspected at various stages as per the quality assurance plan. FRP fans provide substantial energy savings as compared to conventional aluminum and MS fans thereby reducing initial equipment & operational cost.
The project on development of FRP Axial Flow Fans was launched in September 1998. All the development activities encompassing designing the fans, selection of raw materials, stabilizing fabrication procedure & finally performance testing of four fans were completed by December 1999. The fifth fan for radiator cooling application for diesel locomotives for Indian railways was successfully performance tested in January 2000.

Apart from optimally designed impellers, an axial flow fan also comprises other critical components such as fan hub, support plates, fasteners, bushes for fixing the drive shaft etc. The FRP fan blades and the hub are assembled together & are again subjected to static & dynamic balance test and inspected at various stages as per the quality assurance plan. FRP fans provide substantial energy savings as compared to conventional aluminum and MS fans thereby reducing initial equipment & operational cost.

All the development activities encompassing designing the fans, selection of raw materials, stabilizing fabrication procedure & finally performance testing of four fans were completed by December 1999.

Five fans as mentioned above have been developed successfully under the project. The performance evaluation of all the five types of fans established an efficiency differential of around 25% over conventional fans with aluminum impellers. The air heat exchanger fan, fabricated by Resin Transfer Moulding (RTM) technique, tested at the refinery of Indian Oil Corporation (IOC) Ltd., Panipat with over 30% energy saving as compared to existing fans imported from overseas suppliers. RDSO fan has also been fabricated by RTM and tested as per ANSI/AMCA with improved performance.