This document describes the Water Flow Calibration Facility (WFCF) at the National Institute of Standards and Technology (NIST). This facility has three parallel pipelines with diameters of 100, 200 and 400 mm and three weighing systems with capacities of 1100 kg, 3700 kg and 22500 kg. Part of the WFCF which includes a 3700 kg collection tank and a 100 mm pipeline (for the sake of simplicity hereafter referred to as WFCF 3700/100) is now complete and operated by Fluid Metrology Group. The WFCF 3700/100 is used to provide water flowmeter calibration services as reported in  for the Calibration Service ID Number 18020C. The WFCF 3700/100 uses the static gravimetric method  and an error free uni-directional diverter and collection/bypass (CB) unit to perform water flowmeter calibrations between 40 L/min and 1600 L/min. It measures flow by weighing the water in the 3700 kg tank during a measured time interval [ISO 4185]. The expanded uncertainty of the flow measurement is 0.033 % when a full tank is weighed (k = 2 or approximately 95 % confidence level).
Citation: Special Publication (NIST SP) - 250-73Report Number:
NIST Pub Series: Special Publication (NIST SP)
Pub Type: NIST Pubs
calibration, correlated uncertainty, diverter, flow, flowmeter, mass calibration, meter, uncertainty, water flow standard