Calibration and verification

Calibration compares a meter's reading with a reference of known accuracy, such as a test bench with a measuring tank, and records the error at set flow rates; any adjustment is a separate step. Verification checks that those errors fall within the maximum permissible error, and ends in a pass or a fail.

A calibration certificate tells you how far off a meter was; a verification tells you whether it met the standard. Ask which one a test report shows before relying on it.