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R9 Laboratory SOP 815
BALANCE CALIBRATION AND MAINTENANCE
Summary
Precision weighing equipment is used throughout the EPA Region 9 laboratory to prepare reagents, standards, and samples for analysis. The precision and accuracy of all the data generated by the laboratory rely on these balances (analytical and top loader). Systems are in place to maintain and monitor all the balances so that the precision and accuracy of all measurements associated with each balance can be demonstrated. All balances are serviced by a certified technician annually and whenever performance indicates repair is necessary. In addition, prior to each use balance performance must be demonstrated by determining the weight of a series of calibration weights. Calibration weights themselves are verified on a quarterly basis against a set of NIST Class S weights which are in turn certified every three years.
The procedures described in this SOP apply to all balances employed by ESAT for all analytical mass determinations. Balances at the Region 9 laboratory are maintained and repaired by the EPA. Balances used by FASP are the responsibility of ESAT and will be maintained and repaired by ICF Kaiser under the ESAT contract. All procedures regarding the daily use of balances apply equally to FASP and the Region 9 laboratory.