Sterlco SF1000 Gravimetric Additive Feeder - Manual (Page 31)

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Appendix A: Load cell protection device
1. The load cell is a delicate element, very sensitive to extreme mechanical vibration and
shocks. In order to prevent any damage that might be caused by such vibrations or shocks, a
special mechanical device, as described below, protects the load cell.
2. The protection device (see fig. A), is actually a “movement limiter,” comprised of a base
(1) and a stopper with a hole (2), attached to the load cell. Inside the hole there is a limiting
pin (3) which, while in "locked position", prevents any undesired movement of the load cell
during transportation. The limiter is fastened to its base by nuts (4) and locking washers (5)
which prevent release of the nuts.
3. When the unit leaves the factory, the protecting device is its "locked position" (safe state)
in order to prevent any damage to the load cell during the transportation and installation.
4. After installation, before starting to operate the feeder, you should release the limiter
from its "locked position" to "unlocked position" (work state). Rotate the limiting pin one half
turn - the pin will then drawn back from its locking position by its spring to its unlocked
position, allowing a clearance of 0.5mm (0.02") around it. The clearance ensures enough
space for normal movement of the load cell during regular weighing operation, yet it limits
and prevents any extreme irregular displacement that might cause damage to the load cell.
5. The limiting pin in its "unlocked" position is fixed in the center of the stopper's hole,
ensuring the minimum clearance required for the normal movement of the load cell during
operation. If for some reason there is a displacement from the center, it might interfere with
the regular operation of the load cell, and cause incorrect weighing results. In this case, the
nuts and its locking washers should be released, and the limiter should be readjusted in the
center of the hole and fastened again with the nuts and locking washers. It is recommended
that you use a measuring device to ensure the min. 0.5mm clearance all around.
6. It is required to relock the safety device each time that the Sterling SF-1000 is
dismantled from the injection or extrusion machine and being moved to another
location or machine.
Note that there is no guarantee for the load cell for any mechanical damage, or
damage caused by an overload.