Page 956 - Flipbook_SolidDesignSoutheast2020

2.4. Sensitivity

The theoretical sensitivity of a given metal detector is determined by the
aperture size; the smaller the aperture, the smaller the piece of metal that
can be detected. The smaller dimension of rectangular apertures is used
to calculate the sensitivity, although the length also contributes.
Metal Size
To maximize sensitivity a detector the smallest size aperture should be
selected. However there are some exceptions:
 Metalized Film
 Oxygen Scavengers Aperture Size
 Highly Conductive product (large blocks of cheese)
Figure 5

Product effect, metal free area, type and orientation of contaminant and
other factors can affect the practical sensitivity in any application.

The position in the aperture also affects the sensitivity (see figure 6).
The centerline axis is the least sensitive point and therefore this is where
3
performance testing should take place. As metal gets closer to the sides
(and coils), the signal it generates gets larger, making it easier to detect. 1 2

Regular testing of the detector should be done so that the test sphere
passes close to the center of the aperture. If this is not easily done, then a
consistent position should be used so that the test results will be consistent Figure 6
(see figure 7).

Signal Size

1 2 3
Position in Aperture

Figure 7

51 Grand Marshall Drive | Toronto, ON | M1B 5N6 | Canada | Tel: 888.220.8737 / 416.754.2898 | www.fortresstechnology.com
Copyright © 2014 Fortress Technology Inc. All rights reserved. The information, designs and artwork contained in this document are confidential and may not be
disseminated, distributed or copied without written consent from Fortress Technology Inc. Specifications, designs, features and technology subject to change without notice. Page 4