Pneumatic conveying electrostatic charging

There was no significant damage to equipment in the fire tests, and it was demonstrated that a Jet Airmix mixer may safely handle the mixing of RP formulations on a routine basis. Since a high risk of fire is always associated with any method of transfer of RP, a pneumatic conveying system [dynamic air, two phase positive pressure transfer system was evaluated to load RP into the Jet Airmix mixer. Electrostatic charge measurements were minimal and indicated the system was satisfactory to load the blender. 

Enstad, G.G., Electrostatic Charging of Powders by Pneumatic Conveying, Chr. Michelsen Inst. Report Ref. CMI no. 78001-1, April 14, 1978. 

The capacity of pneumatic-conveying systems depends on several factors besides the characteristics of the solids, such as the diameter of the conveyor line, the length of the line, and the energy of the conveying air. In fact, some materials (e.g., sulfur) build up an electrostatic charge and may cause explosion risks. 

Cartwright P. Singh P, Bailey A. et al. Electrostatic charging characteristics of polyethylene powder during pneumatic conveying. IEEE Trans Ind Appl 1985 l(A-2I) 541-6. 

After first having to deal with the hazards of electrostatic generation in pneumatic conveying and their adverse effects on electronics, these phenomena can be channeled into a useful tool for measurement. The charges generated in the conveying operation can be measured at two distinct points, and these signals can be cross-correlated to provide a measure of the particle velocities. In fact, one can use a coil as an antenna... 

Gajewski A. Measuring the charging tendency of polystyrene particles in pneumatic conveyance. Journal of Electrostatics 23 55-66, 1989. 

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