7.3. Selection of Ending Criteria
The decision of which ending criteria to use is application dependent. Best results are typically given with PREDICTION or RATE, rather than TIME. Experiment with your particular sample to determine which criterion is best for your product. See Ending Criteria on page 26.
For PREDICTION, the MAX 5000XL uses a sample dependent test to automatically end a test. The test, called the reliability criterion, is equal to the "actual moisture loss" at a given moment divided by the end point predicted by the microprocessor times 100. The ending ratio can be set to a value from 00 to 99 depending on the user's desire to balance speed and accuracy. The smaller the number, the sooner each test will end. A value of 99 means the actual moisture loss must exceed 99% of the predicted end point.
For RATE, the MAX 5000XL ends the test when the sample weight loss rate has fallen below a preset percentage value. This is useful for samples that do not conform to the standard exponential drying model but will show a consistent moisture rate loss at some point in the process. The parameter may be set for values from 0.0010% to 9.9999% loss rate.
For TIME, the MAX 5000XL ends the test after a preset time of up to 120 minutes has past. This is sometimes useful for diagnostic and research purposes.
Use “TEMP THEN …” to prevent a test from ending before the test temperature has been obtained. This can be helpful for ashing, which takes a while to reach the final temperature, and for testing ultra low moisture samples, which don’t readily release moisture at the beginning of the test.
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