CHAPTER 4 – FINAL TESTING
MB90 MB120 Series Service Manual
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Ohaus Corporation www.ohaus.com
CHAPTER 4 – FINAL TESTING
4.1 Final tesing
Before servicing the MB90 or MB120 Moisture Analyzer, an operational test and various
performance tests should be done to determine if the unit meets specifications. Turn the
Moisture Analyzer on and allow it warm up for at least one hour before performing these tests.
NOTE:
Make sure the test area is free from drafts and the surface the Analyzer rests on
is level and vibration-free. An ASTM Class 1, or OIML Class E2 Tolerance mass
should be used for the performance tests and adjustments.
4.2 Operational Test
Check the Analyzer’s voltage rating, and plug the Power Cord into a suitable power source.
4.3 LCD Display Test
Turn the Moisture Analyzer on, and ensure the LCD are display normal with no missing
segment.
4.4 Performance Tests
Accurate performance is determined by a series of three performance tests: Precision, Off-
Center Load and Centered Load. The displayed readings are compared with the tolerances
listed in Table 4-1. Before starting the performance tests, level the Moisture Analyzer.
TABLE 4-1. TYPES OF PERFORMANCE TESTS & TOLERANCES
PERFORMANCE TEST
Tolerance: MB90
Tolerance: MB120
Precision (Std Deviation)
±0.2g
±0.2g
Repeatability (Std Dev)
0.18% (3g sample)
0.05% (10g sample)
0.05% (3g sample)
0.015% (10g sample)
Note: Ideal test sample e.g. 5% +/-1% NaCI solution is required for moisture repeatability test.
The following performance tests are used to evaluate the Moisture Analyzer operation before
and after repairs. Each Moisture Analyzer tested must meet the requirements specified in each
test as well as the specifications listed in Table 1-1. A Moisture Analyzer which passes each of
these three tests meets the manufacturing specifications.
