OHAUS DISCOVERY BALANCE, Руководство по обслуживанию

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CHAPTER 4 TESTING
4.2.2 Adjusting Off Center Load
6. Adjust as shown until the reading is two to three times the the specifications in
Table 1-2. Then re-test as shown in Section 4.2.1.
6.1. Use small adjustments, no more than a quarter-turn at a time.
6.2. As you get close to the tolerance you have to reduce the amount of the turn.
7. Work front-to-back first, then side-to-side.
8. This process is complete when all four edges of the Pan are within tolerance
specifications.
4.2.3 Repeatability Test
Repeatability is a word used in balance specifications meaning the Standard Deviation of a set
of similar weight readings. To determine whether a balance meets the calculated Standard
Deviation value in the Specification Table 1-2, perform the following test:
1. Tare the balance. The reading on the display should be 0g.
2. Select a mass weighing near the maximum capacity of the balance and place the
mass on the center of the Pan. Observe and record the reading.
3. Remove the mass. Reading should return to 0g ± 1 count.
4. Repeat the test for ten readings. If the standard deviation of the readings is within
the specifications in Table 1-2 (Discovery Balance Model Specifications, page 1-3),
the balance passes the Repeatability Test.
4.2.2 Remediation
If the deviation for any set of readings (using the same mass placed on the center of the Pan) is
greater than the specifications in Table 1-2, the balance does not meet the Repeatability Test
specification. Inspect and correct the following areas:
1. Check for mechanical obstructions. Any foreign object touching any part of the
moving Pan can cause a balance to fail the Repeatability Test specification. Inspect
and correct if necessary.
2. An error in the Off-Center Load Test can affect the results of the Repeatability Test.
Inspect and correct if necessary. See Section 4.2.3 - Off-Center Load Test.
3. Foreign material or debris located in the balance between the Pan, and the Draft
Shield Bottom can cause the balance to fail the test.
4. Environmental influences such as vibrations, drafts or a non-level surface can also
cause failures.
Ohaus Corporation www.ohaus.com 4-4 Discovery Balance Service Manual