When we do a EFM Calibration or verification, our trained staff follow all manufacturer’s recommended procedures. We the calibration and verification requirements in AER Directive 017 are followed.
We also verify not only the EFM itself, but check the orifice run and inspect the orifice plate and changer if possible. We have found damaged orifice seals, and nicked plates which affect accuracy. For example we found a large error caused by an orifice plate with the wrong size stamped on it which was in service for several years. This was found by routinely checking orifice plate sizes with calipers.