CHAPTER 4 TESTINGOhaus Corporation www.ohaus.com 4-2 Pioneer™ Balances Service Manual4.4 Performance Tests – Precision and Analytical BalancesAccurate performance of the Pioneer balances is determined by a series of four performancetests. 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 onthe balance display.TABLE 4-2. TOLERANCES – PRECISION MODELSPerformance Test TOLERANCE – COUNTS150g 210g 310g 410g 510g 1500g 2100g 3100g 4100gPrecision (counts) ±1 ±1 ±1 ±1 ±1 ±1 ±1 ±1 ±1Off Center Load (mg) ±2 ±2 ±2 ±3 ±30 ±30 ±30 ±30 ±40Repeatability (mg) ±1 ±1 ±1 ±1 ±10 ±10 ±10 ±10 ±10Linearity (mg) ±2 ±2 ±2 ±2 ±20 ±20 ±20 ±20 ±40TABLE 4-3. TOLERANCES – ANALYTICAL MODELSPerformance Test TOLERANCE – COUNTS65g 110g 210gPrecision (counts) ±1 ±1 ±1Off Center Load (mg) ±0.2 ±0.2 ±0.3Repeatability (mg) ±0.1 ±0.1 ±0.1Linearity (mg) ±0.2 ±0.2 ±0.3NOTE:The following performance tests are used to evaluate balance operation beforeand after repairs. The balance must meet the requirements specified in each testas well as the specifications listed in Tables 1-1 – 1-4.Before proceeding with the following tests, the balance should be warmed up forat least five minutes, and calibrated. (See Appendix A.)4.4.1 Precision Test – Precision and Analytical BalancesThe Precision Test measures the Standard Deviation of a set of similar weight readings, whichshould 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 onthe 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 readingrecorded. If so, the balance passes the Precision Test.
