When to calibrate?

UL calibration requirements stipulate that inspection, measuring and test equipment (including flow meter) must be calibrated at least annually for their intended function and use or whenever the flow meter has been subject to some form of abuse that may affect the measurement device fitness for use.

GOP(good operating practices) also recommends that you calibrate your flow meter every six months if you are using a new meter or one located in an hostile environment until you get an accurate "footprint" of the meter and then switch to yearly calibrations. Also, it is strongly recommended for companies requiring FDA approval to calibrate their flow meter on shorter calibration schedule in order to investigate early minor deviation from the standards.