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.