OHAUS SD Series, Service Manual

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CHAPTER 4 TESTING
4.8 Linearity Test
This test is used to determine the linearity of the unit throughout its operating range.
The masses used to perform this test can be utility masses.
NOTE:
The scale must pass the Repeatability and Off Center Load tests, and be calibrated,
before the Linearity Test may be performed.
TABLE 4-2. LINEARITY TEST MASSES
Capacity & Readability
SD35 SD75 / SD75L SD200 / SD200L
Reference Mass 10 kg / 20 lb 25 kg / 50 lb 50 kg / 100 lb
Load 1 10 kg / 20 lb 10 kg / 20 lb 50 kg / 100 lb
Load 2 20 kg / 40 lb 25 kg / 50 lb 100 kg / 200 lb
Load 3
25 kg / 50 lb 50 kg / 100 lb 150 kg / 300 lb
NOTE:
All masses are nominal values. Be certain to use the same reference mass throughout
the procedure.
1. Place the reference mass on the Scale, record the weight and remove.
2. Place Load 1 on the Scale and press ON/ZERO Off .
3. Place the reference mass on the Scale, record the weight and remove.
4. Place Load 2 on the Scale and press ON/ZERO Off .
5. Place the reference mass on the Scale, record the weight and remove.
6. Place Load 3 on the Scale and press ON/ZERO Off .
7. Place the reference mass on the Scale and record the weight.
8. The difference in the weights of the test mass should be within the tolerance in the
relevant Specification Table in Chapter 1. If not, calibrate (see Section 1.8) and
repeat the test.
9. If the Scale remains out of tolerance, the base may need to be replaced.
Ohaus Corporation www.ohaus.com 4-6 SD Series Scales Service Manual