Thermo Scientific APEX 100 User Manual page 296

Conveyor Separation
If there is a separate conveyor for the metal detector system, be certain this conveyor
does not make contact with the in-feed and discharge conveyors. Fastening them with a
non-metallic material is the recommended method, as shown below.
Loop Effects and Roller Isolation
Besides observing rules for metal-free areas, precautions must be taken to prevent the
occurrence of loop effects. A loop effect is caused by an electrical loop in the conveyor,
making intermittent contact.
Loop effect is caused by an electrical loop in the conveyor, making intermittent contact.
This loop, when closed, can produce large electromagnetic fields. When the loop opens,
the field collapses very rapidly, causing the detector's field to be disturbed. This results
in false detection.
The following can cause loops.
• Rollers whose bearings make an intermittent connection.
• Any metal that crosses the conveyor frame and is not securely fastened—such as
the transfer plate, loose cross members, electrical conduit, and retracting-reject
or flap-gate reject devices.
Page 296 Thermo Scientific APEX User's Guide