OHAUS Valor 1000W, Service Manual

Page: 29 / 44

CHAPTER 4 TESTING
Valor
™ 1000W Series Service Manual
4-5 Ohaus Corporation www.ohaus.com
4.6.3 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 Precision and Repeatability Tests, and be calibrated before
the Linearity Test may be performed.
TABLE 4-3. LINEARITY TEST MASSES
Capacity (g)
3000 x .5g 6000 x 1g 15000 x 2g 30000 x 10g
Reference Wt. 1000 1500 4000 8000
Load 1 500 1500 3000 6000
Load 2 1500 3000 9000 15000
Load 3 2000 4500 11000 22000
NOTE:
All masses are nominal values. Use the same reference mass throughout the procedure.
1. Place the test mass on the Scale, record the weight and remove.
2. Place Load 1 on the Scale and press ON/ >O/T< .
3. Place the test mass on the Scale, record the weight and remove.
4. Place Load 2 on the Scale and press ON/ >O/T< .
5. Place the test mass on the Scale, record the weight and remove.
6. Place Load 3 on the Scale and press ON/ >O/T< .
7. Place the test mass on the Scale and record the weight.
8. The difference in the weights of the test mass should be within ±2 d, as specified in
the Tables 1-1 and 1-2. If not, calibrate (see Appendix A.1) and repeat the test.
9. If the Scale remains out of tolerance, the Load Cell may need to be replaced.
4.4.4 Off-Center Load Test
The Off-Center Load Test is used to determine whether displayed weight values are affected by
moving the sample to different areas of the Pan.
1. Place half of the
scale’s capacity in the center of the Pan.
2. Note the reading.
3. Move the mass halfway (between the center and the edge) to the front of the Pan.
Note any differences in the displayed weight reading.
4. Repeat the test for the back, left, and right position of the Pan.
5. Maximum allowable change in displayed weight readings for each of the four
positions can be found in Tables 1-1 and 1-2 (Specifications, page 1-2 and 1-3).
If this maximum is exceeded, follow procedures in Section 4.4.5, Adjusting Off
Center Load.