CHAPTER 4 - TESTING
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26
Pioneer PJX Series Service Manual
4.4
PERFORMANCE TESTS
Accurate performance of the Pioneer PJX Series balances is determined by a series of four
performance tests. The displayed readings are compared with the tolerances listed in Tables 1-1.
Tolerance values are expressed in counts. A one-count difference is shown in the last digit on the
balance display.
The following performance tests are used to evaluate balance operation before and after repairs.
The balance must meet the requirements specified in each test as well as the specifications listed in
Table 1-1. Before proceeding with the following tests, the balance should be warmed up (60
minutes) and calibrated. (See
Appendix A
)
4.4.1
Precision Test
The Precision Test is a quick test that measures the deviation of a limited number of weight
readings. If the balance passes the precision test than the following tests should be performed.
Note:
This is a reference test for approved models (OIML and NTEP). It is not a required test but it
can be used to determine if the balance is working properly.
1. The reading on the display should be 0g.
2. Select a mass weighing near the maximum capacity of the balance, and place it on the center
of the Pan. Observe and record the reading.
3. Remove the mass. The reading should return to 0g ± 1d.
4. Repeat this test three times. The readings should be within ± 1d. If so, the balance passes the
Precision Test.
If the deviation for any set of readings (using the same mass placed on the center of the Pan) is
greater than 1d, the balance does not meet the precision specification. Inspect and correct the
following areas:
-
Check for mechanical obstructions. Any foreign object touching any part of the moving
assemblies will cause a balance to fail the Precision Test. Inspect and correct as necessary.
-
If the balance does not meet specifications, move it to a suitable location, ensure that it is
level, and try again. If it still does not meet specifications, perform a service calibration, and try
again. (See
Appendix B
for Service Calibration)
-
If the balance does not pass this test, the Load Cell may need to be replaced.
4.4.2
Repeatability Test (non-approved models)
The repeatability specification is defined as the Standard Deviation value derived from a set of
weight readings. This test uses more weight data than the Precision Test and will allow for
occasional weight deviations due to testing variations.
Note: The required method for approved models (OIML and NTEP) is shown in the following
section.
Requirements:
•
To perform this test a single mass must be used for all readings.
•
The test mass should be approximately ½ of the capacity of the instrument.
•
Wear gloves when handling the mass.
Set Up:
Before starting a repeatability test, set up the instrument as follows.
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