We recently presented and tested a model for a dynamic gravimetric standard for steady water flows. In the range 10 kg/s to 60 kg/s, the difference between the dynamic standard and NIST's static primary standard was 0.015 % with a standard deviation of 0.033 %, Here, we extend the model for the dynamic gravimetric standard to account for unsteady flows and we account for the different response times of the dynamic standard and an electromagnetic flow meter (EMF). After these improvements, we measured water flows with diverse time dependences during 100 s collection intervals. These flows averaged 12 kg/s; however, the flows ramped or stepped up or down 5 kg/s. When integrated over the collection interval, the difference between the dynamic standard and a statically-calibrated EMF was 0.008 % with a standard deviation of 0.012 %. This agreement justifies the further study of the dynamic standard, particularly at higher flows where the mechanical simplicity of a dynamic standard might reduce the cost of accurate measurements.
Proceedings Title: Measurement Science Conference
Conference Dates: March 23-27, 2009
Conference Location: Anaheim, CA
Pub Type: Conferences
flow measurement, primary standard, dynamic gravitational method, flow metrology