Needle detector has very high demand to the working environment. To make sure the equipment works correctly, the magnetic source should be away from the equipment. Motor, transformer, magnetic card, mobile may disturb the working of needle detector. Secondly, the needle detector should work on the flat and stable surface.
In the on-site management:
（1）check the equipment’s sensitivity. Before use each time, the operator must examine the sensitivity with the examination card at least three times by different angles. Only when the examinations pass can the needle detection starts.
（2）If the needle detector gives warning to the subject, contact the equipment manager and find out the impurity. If the equipment doesn’t give warning after five times’ detection, the manager should write down ”needle reminding but no problem by further detection” in the record.
（3）If the subject can’t pass the needle detector by several times and no impurities can be found, the subject should be marked as abandoned.
（4）The packaged box of the subjects that pass the needle detector should be stamped with date and needle detector operator’s name. The operator takes responsible for it.
（5）When the counter of the needle detector is on, the tested subjects should be placed within 30cm distance. In order that the counting is correct, even if there is no needle, the alarm will warn. The reason why the subject can pass when the alarm warns is the distance between the subjects is too narrow. What’s more, if the distance is less than 10cm, two subjects may be counted as one and the alarm will not warn. So the operator must pay special attention to this distance. If the counter is off, the distance alarm will not work. If it warns, it means needle mixes, so the belt will stop and reverse.
