PDFWAC 173-173-120
What are the operation and maintenance requirements for meters on pressure systems?
(1) Meters shall be inspected and maintained as specified by the manufacturer.
(2) Meters shall be field or shop calibrated, as specified by the manufacturer. Meters also shall be field or shop calibrated and/or repaired if they are over or under registering. System diagnostics may substitute for physical calibration of nonmechanical meters.