Design Step 3 - Determine Capacity, Size and Speed

In order to determine the size and speed of a screw conveyor, it is first necessary to establish the material code number and design capacity. In Step #2 you identified the material code number, the following will illustrate how this code number determines the cross-sectional load of the conveyor that should be used. For applications where special types of screws are required; such as short pitch screw, cut flights, cut and folded flights and ribbon flights, a design capacity must first be calculated. The design capacity is found by mulitplying the required capacity by one or more of the capacity factors that are involved. See Table C, Table D, Table E and Table F for capacity factors.

Design Capacity Calculation:

     Design Capacity = Required Capacity x Capacity Factor(s)

Speed of Conveyor (rpms)

     Speed = Design capacity / 1 rpm capacity

The "1 rpm capacity" and the "maximum recommended speed" can be obtained from Table H

Table C:      Maximum Lump Size

Table D:     Flight Factor

Table E:     Pitch Factor

Table F:     Ribbon Factor

Table H:      Conveyor Size and Speed