Arizona Instrument COMPUTRAC MAX 4000, User Manual

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10.2. Sodium Tartrate Test
The (Factory) TARTRATE test verifies the heater and force balance operation. Sodium
tartrate dihydrate is a chemical with a known moisture content that releases moisture at
temperatures greater than 120 ºC.
Because of its consistent moisture content, sodium tartrate is used as a standard in
moisture measurement using oven or titration methods. To obtain consistently reliable
results, use a high quality or reagent grade (ACS certified) granular sodium tartrate. Sift
the sodium tartrate through a #20 sieve to obtain a more uniform size and produce better
results. Lumps in sodium tartrate usually indicate moisture absorption that will yield
inconsistent results. Discard the larger chunks, or pestle them through the sieve and
return them to the bottle.
Sodium tartrate (AZI P/N: 800-0037) is available from AZI consumable parts sales.
See section
7.1 Performing a Test on page 36 and select (Factory) TARTRATE as the
Test Program to perform the TARTRATE test. The Test Program is factory configured to
use approximately 8 grams of sample and run at 150 °C. Test Results should be within
a range of ±0.1 of the assayed value on the label of the chemical. Sodium tartrate
assayed moistures typically range from 15.61 - 15.71.
Discard the first test result of the day for stability reasons.
If desired, perform the sodium tartrate test multiple times to determine the instrument’s
repeatability. This is a more critical verification of the instrument’s performance. Perform
five tests and then compute the mean, standard deviation, and relative standard deviation
(See section
8.2 Test Results on page 55 ).
If the results are out of tolerance, then:
•
Check for bent or dirty sample pans; use new/clean sample pans for each test.
•
Carefully clean the chamber interior (See section 11.1 Heat Chamber on page 95 ).
•
Check the balance shaft for debris (See section 11.2 Balance Shaft Check on page
96 ).
•
Clean the heater and check the temperature sensor (See section 11.3 Heater
Cleaning on page 96 ).
•
If a Temperature Calibration Kit is available, temperature calibrate the system (See
section 8.3.2 Temperature Calibration on page 63 ).
After performing the above suggestions, repeat the sodium tartrate test again, and
analyze the results. If the results are still out of tolerance, call AZI Customer Service for
assistance.