On the Dead Volume of a Standard Small Volume Prover |
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| Maria H. Farias, Marcos V. B. Ramos, Sandro R. Santoro |
- Abstract:
- The calibration procedures of compact provers, which are used as standards to calibrate volumetric meters, are well known. However, the reduction of uncertainty of measurement in a prover calibration or when using a prover as standard depends on several factors, among them, the way of controlling some quantities, the kind of valves in the hydraulic circuit and how they are operated, the kind of liquid totalizer in calibration etc. In general, position sensors installed close to the initial and final ends of the cylinder ruler of the prover indicate the useful displacement along the tube. Such sensors limit the dead volume in the cylinder ends, which is not defined by the equipment user. On the other hand, if these dead regions, which are affected by the dynamics of the prover operation were evaluated by the user, the result could be different from that indicated by the supplier. The present work discusses that matter and, based on experimental data, analyzes the useful length for the cylinder of a small prover (09 L) which belongs to Inmetro (the Brazilian National Metrology Institute). A system for controlling and acquiring data has been created and adapted to the prover, and it is able to score pulses in two distinct counters, improving the equipment resolution. Besides making possible to investigate the size of dead spaces of the cylinder, such system could eliminated sensors at the final and initial positions of the tube ruler. The prover was calibrated by gravimetric water draw method under multiple samples along the cylinder length and using the two distinct pulses counters.
- Keywords:
- Compact prover, Volumetric meters, Flow rate, Dead volume
- Download:
- IMEKO-TC9-2010-075.pdf
- DOI:
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