This document discusses the procedures for submitting a flow meter for calibration, gives the readily available pipe sizes and flanges suitable for flow meter calibration, documents the format of a standard NIST calibration report, and states the normal range of data collected for a calibration. In addition, this document describes the theory, principle of operation, and uncertainty of the 26 m3 PVTt primary flow standard covering the flow range from 200 L/min to 77000 L/min. Details concerning the two smaller PVTt flow standards can be found in the following reference.