# Screw Pump Sizing

1. Oct 12, 2012

### hmvyoral

Does anyone know where i can get the calculations for sizing an inverted screw pump. Inverted being that there is no screw but the fins art attached to the inside of a pipe and the pipe is rotating. I am moving any where from 150 to 400 lbs of dry powder per minute, depending on the amount of powder being produced. I dont have the exact length yet, hence why i just need the formulas. The idea is to find the diameter, fin height, spiral patern, and speed. If anyone knows where i can get the calculations i would apreciate the help.

2. Oct 13, 2012

### Staff: Mentor

Use the equations for a regular screw pump. It doesn't matter whether the screw is rotating and the casing is stationary or the casing is rotating and the screw is stationary.

3. Oct 15, 2012

### hmvyoral

I would like to use the equations for a screw pump, but i am unable to find any online. I had figured that everything would be the same because all i did was eliminiate the screw shaft and put the fins on the wall of the casing. If you know where i can get some calculations i would apreiciated it.

4. Oct 16, 2012

### Staff: Mentor

Try looking in the Polymer Processing literature in the area of extrusion. They use screw pumps (extruders) to compact and melt granular and powdery solids as part of producing a polymer melt. Look under the names of Bernhardt, Tadmor, Tadmor and Klein, and Osswald. In order to design a screw pump for a granular material, you need to have some idea of the rheological behavior of the granular material on a scale somewhat larger than the particle size. I'm not sure how much work has been done in this area, since I haven't followed it. But consider looking under the subject of Deformational Behavior of Granular Materials. In a screw pump, kinetic friction on the granular bed is also important. I hope this is helpful.

5. Oct 19, 2012

### hmvyoral

Thank you, I will start looking into that. I will let you know if i find anything.