Vern E. Bean, Pedro I. Espina, John D. Wright, J F. Houser, Sherry D. Sheckels, Aaron N. Johnson
NIST provides calibration services for metal volume provers for liquid volumes from 4 L to 7600 L using gravimetric and volumetric methods. This document describes the procedures and methods of calculation used in the calibration service. The covered methods are: the direct weighing of neck scale and slicker plate provers, the pre-weighed water method, the weigh tank method, and three variations of the volume transfer method. We also describe methods for calibration of neck scales on volume provers. Sample uncertainty analyses are provided for three gravimetric calibrations and one volume transfer calibration. Typical uncertainties for neck scale provers are 0.015 % + 0.003 gal or 0.015% + 0.012 L (about 0.3 % for a 1 gal (3.8 L) volume prover and 0.02 % for a 100 gal (380 L) prover).