Screw / Auger Conveyor Capacity
Volumetric capacity (ft^3/hr) from diameter, shaft, pitch, RPM, and trough loading, and mass rate from a bulk density.
Example
You enter
- Screw diameter (in) 9
- Shaft / pipe diameter (in) 2.5
- Pitch (in) 9
- Screw speed (RPM) 40
- Trough loading fraction (CEMA class) 0.3
- Bulk density (lb/ft³, optional) 45
You get
- Volumetric capacity 220.2 ft^3/hr
- Mass rate (lb/hr) 9907.06
Checked against published worked examples from: CEMA Screw Conveyor standard (Book No. 350).
Details, formula, and sources
ScopePer the CEMA Screw Conveyor standard (Book No. 350); loading fractions user-supplied per CEMA class.
Formula or tableQ (ft^3/hr) = (pi/4)(D^2 - d^2) x pitch x RPM x loading x 60, all in feet; mass rate = Q x bulk density.
Source and editionCEMA Screw Conveyor standard (Book No. 350) capacity method, by name.
Free accessCEMA-published; the swept-volume capacity relation is public. CEMA and the manufacturer govern.
What governsEstimate. AHJ and licensed professional govern.
API field namesscrew_diameter_in, shaft_diameter_in, pitch_in, rpm, loading_fraction, bulk_density_lb_ft3, capacity_ft3_hr, mass_rate_lb_hr
- Loading fraction per the CEMA material class (light ~30-45%, heavy/abrasive lower); user-suppliedCEMA Book No. 350