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Title: Primary Calibration Of Gas Flows With A WEIGHT/TIME Method
Author: R. E. Harris, J. E. Johnson
Source: 1990 International Symposium on Fluid Flow Measurement
Year Published: 1990
Abstract: A primary calibration facility for gas flows has been developed which incorporates the fundamental variables of weight and time for estimation of mass flow rates. The facility is a pressurized closed loop system capable of rapidly directing gas that has flown through a metering section into a receiver tank. After a specified time interval, flow diverted into the tank is redirected into the loop where normal closed loop flow operations continue. Pressure within the loop is maintained during the diversion process by supplying makeup gas. The mass of gas collected is determined by a gyroscopic weight scale capable of resolving 2.5 grams with a tare weight of 2000 Kilograms. Significant testing and tuning was conducted to minimize disturbances in upstream flow conditions over the complete mass flow rate range of the calibration facility. Data are presented to indicate the stability in upstream conditions which can be achieved in the flow loop. The equations for estimating mass rates using the weight tank system are presented and combined with estimates of the expected uncertainty. Finally, preliminary data comparing the measured flow rates obtained using the weight tank system and those from a four element nozzle bank are presented.