Performance Tests; Precision Test; Tolerances - Precision Models; Tolerances - Analytical Models - OHAUS PA64 Service Manual

CHAPTER 4 TESTING
Performance Tests – Precision and Analytical Balances
4.4
Accurate performance of the Pioneer balances is determined by a series of four performance
tests. The displayed readings are compared with the tolerances listed in Tables 4-2 and 4-3.
Tolerance values are expressed in counts. A one-count difference is shown in the last digit on
the balance display.
Performance Test
Precision (counts)
Off Center Load (mg)
Repeatability (mg)
Linearity (mg)
TABLE 4-3. TOLERANCES – ANALYTICAL MODELS
Performance Test
Precision (counts)
Off Center Load (mg)
Repeatability (mg)
Linearity (mg)
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 Tables 1-1 – 1-4.
Before proceeding with the following tests, the balance should be warmed up for
at least five minutes, and calibrated. (See Appendix A.)
4.4.1 Precision Test – Precision and Analytical Balances
The Precision Test measures the Standard Deviation of a set of similar weight readings, which
should match the specification for each model, listed in Tolerance Tables 4-1 and 4-2.
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 it on
the center of the Pan. Observe and record the reading.
3. Remove the mass. The reading should return to 0g ±1 count.
4. Repeat this test three times. The reading should be within ±1 count of the reading
recorded. If so, the balance passes the Precision Test.
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TABLE 4-2. TOLERANCES – PRECISION MODELS
150g 210g 310g
±1 ±1 ±1
±2 ±2 ±2
±1 ±1 ±1
±2 ±2 ±2
TOLERANCE – COUNTS
410g 510g
±1 ±1
±3 ±30
±1 ±10
±2 ±20
TOLERANCE – COUNTS
65g 110g
±1 ±1
±0.2 ±0.2
±0.1 ±0.1
±0.2 ±0.2
NOTE:
4-2 Pioneer™ Balances Service Manual
1500g 2100g 3100g
±1 ±1 ±1
±30 ±30 ±30
±10 ±10 ±10
±20 ±20 ±20
210g
±1
±0.3
±0.1
±0.3
4100g
±1
±40
±10
±40