Automated Test Weight Lifter for "M" Style Weigh Belts
More and more weigh feeders are being used in conjunction with statistical process control where performance records are routinely
generated and recorded as required by a customer's quality assurance program. Such a record should contain a "validation of scale
calibration" step to be truly meaningful as a quality assurance tool. Thayer Scale's Automated Test Weight Lifter ("ATWL") provides
a means for automatically applying a known test weight and going through a calibration sequence on computer or push-button
demand to check scale calibration. A "foolproof" self-checking software algorithm in the feeder control instrumentation prevents
erroneous calibration.
CALIBRATION is fast, accurate and reliable
Thayer Scale's test weight calibration method has proven accurate and reliable over
decades of in-plant use. Unlike material sampling, it is always clean, fast and safe.
Unlike electronic signal simulation, it actually tests the performance of critical electro-mechanical components under the full deflection range of the load cell. Adding
the THAYER Automated Test Weight Lifter now makes calibration even easier and
more exact.
Other Methods of Calibration :
Electronic Signal Simulation: Fast, but does not apply load to scale.
Test Chain: Difficult to use, storage can be a problem, time consuming, susceptible
to wear, prone to accidents.
Material Test: Most comprehensive, but very time consuming. Accuracy of calibration
is subject to accuracy of sampling method and accuracy of scale used to weigh
samples.
Thayer Scale's ATWL Features:
- Auto zero calibration check
- Auto span calibration check
- Auto adjustment of zero and span errors
- History of past calibration results stored in instrument for trending and
determination of required calibration interval.
ATWL Benefits:
- Self-storing Test Load can not be misplaced
- Minimizes downtime for calibration checks
- Eliminates risk of injury to personnel
- Assures that correct test load is always applied
- Precisely controls positioning of test load on scale
- Permits full calibration from remote location
- Permits verification of active measurement range
A simple, rugged mechanism holds the test weight above the scale platform during normal feeder operation. Upon demand from the THAYER
instrument, the mechanism lowers the test weight from the storage position
onto the scale platform via a pneumatic air cylinder. For operator supervised
calibration, the operator only touches the YES/NO pushbuttons
on the instrument, which can be placed in a remote location. For automatic
calibration, the THAYER instrumentation is linked to a host computer or
PLC, thereby eliminating the need for operator involvement.
Error findings are automatically logged into the instrument memory and
can be retrieved by the operator at anytime, to review past calibration
results.
Any improper conditions that could invalidate calibration results is detected
by the instrument, which halts calibration and delivers an alarm
massage and diagnosis of the problem to the operator. Calibration has
never been faster, easier or more reliable.
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