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Gravity Metal Detector System—Operator Setup Manual

3.4.3 Delay & Duration

In Gravity applications the reject valve timing is very critical in ensuring contaminant rejection. Reject Delay is the
number of seconds from the moment of detection before the reject device activates. Reject Duration is the number of
seconds for which the reject device will be activated.

If the Gravity system has been supplied complete from Fortress, then the reject timing as well as reject confirmation
settings (if equipped) have already been set and tested. The reject operation should be tested after installation to
confirm that it is operating correctly and the settings adjusted if required.

Test routine: In order to test the reject system timing and operation you will need to drop test samples from the same
point that product will normally start its freefall. You will also need a method to recover these samples if they are not
successfully rejected. If the system is equipped with a test sample retrieval drawer, then the drawer should be manu‐
ally put into the test position below the reject valve. The test retrieval drawer is designed to capture the test samples
in the event that they are not rejected. Prior to performing a drop test, the test samples should be tested on the rails
of the drawer to be sure that they are of the correct size that will not allow them to pass through the drawer but small
enough that the drawer can still be pulled out to retrieve the test samples.

NOTE: For most Gravity applications, the Delay should be set to zero to ensure a fast reject
response time. The Duration can be adjusted based on trial but is typically 0.5 seconds
or less.

Diagram of Reject Delay and Duration is shown below:

Delay & Duration Timing Diagram

Reject Delay Timer
(wait before the Reject Device is activated)

Metal Detected

Reject Duration Timer
(Reject Device enabled pulse) Time

0 Seconds

Reject Adjustment Procedure:
Follow these steps in order to correct the reject accuracy:

1. From the Main Menu press the MENU key once to get to the Reject Menu.

Reject Setup

Del: 0.00 Dur: 0.00

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