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Abstract and Manuscript Management System - Abstract Detail |
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| Speaker: | Anil Agarwal |
| Title: | Characterization of a 100 MPa Controlled Clearance Pressure Balance |
| Topic Group: | Pressure I |
| E-mail: | anil.agarwal@nrc.ca |
| Co-Authors: | |
| Abstract: |
We have recently acquired a 100 MPa operated controlled-clearance pressure balance to be used as a primary pressure standard. In a controlled-clearance pressure balance, a suitable pressure independent of the system pressure can be applied to the outside of the cylinder to control the elastic distortion of the piston-cylinder assembly under high system pressure. To be able to use this device as a pressure standard, it is necessary to first characterize it independently, without comparing it with another standard. In this paper, we will present some of the results of the characterization of this balance using the Heydemann-Welch method. The pressure generated by a controlled-clearance pressure balance at the reference level, using the Heydemann-Welch model, is given as: Here, mi is the mass of the weights loaded on the Piston, is the corresponding density of the mass material, ?a is the density of ambient air, gl is the local acceleration due to gravity, ? is the surface tension of the working fluid, C is the circumference of the piston, Ao is the effective area of the piston-cylinder assembly at zero pressure and some reference temperature tref , ? is the pressure distortion coefficient, Pi is the nominal measured pressure, ?p and ?c are the thermal expansion coefficients of the Piston and Cylinder materials respectively, t is the temperature of the piston-cylinder assembly measured during the operation, pj is the jacket pressure applied to the outside of the cylinder, and pz and d are modeling parameters. The characterization of the pressure balance involves the determination of the pz and d parameters. The undistorted area A0 of the piston-cylinder assembly is determined dimensional measurements. A precision co-ordinate measuring machine (CMM) will be used to determine the diameters of the piston and cylinder at a number of cross sections over the entire engagement length. |
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