Thermo Scientific APEX 100 User Manual page 304

Testing a Gravity-Feed System
When testing a gravity-feed system it is important to test both the sensitivity of the
detector and the response of the reject valve. To accomplish this a metal test sample
must be inserted at or near the zero velocity point of the product. Also a means for
retrieving the test sample after it goes through the system should be incorporated in
case the reject device fails to operate.
Test Procedures for Gravity-Feed and Rx Systems
A complete and thorough test of the metal detector system must be done upon initial
installation and whenever a major component of the system has been changed or
altered. A complete check of the metal detector must include the reject device. Any test
procedure designed for your application should take into account the following.
Pass the Product Through the Detector's Centerline
The metal detector's least sensitive point in the aperture is along the centerline of the
opening. Any testing should be done so that the test sample passes approximately
through the centerline of the opening. If the test sample is run at the side of the product
tube or between the product tube and the detector, this will produce a larger signal than
through the centerline.
Page 304 Thermo Scientific APEX User's Guide