Characterisation of a System that Measures Gas Samples Using a Mass Flow Meter.

摘要

Preparatory work for a gravimetrical in situ calibration procedure A calibration method has been prepared for a new constructed gas cylinder filling station based on a mass flow measurement technique. The construction is located at AGA Gas AB special gas factory in Lidingo, Stockholm, Sweden. Several investigations have been performed on the system and different parameters such as pressure, gas density, and amount of added gas has been analyzed. The calibration method gave a total measurement uncertainty of + or = 281 mg for Nitrogen, + or = 368 mg for Argon and + or = 162 mg for Helium. The principal results of the investigations are: (1) The mass flow meter error is not proportional to the amount of filled gas. (2) The gas filling system is almost always filling over the nominal value, which bothering leads to deviations from the nominal concentration in a gas mixture. (3) A low flow rate causes larger mass flow meter errors. (4) The deviation from the nominally set value increases with line (input) pressure. (5) The mass flow meter error depends on the gas density.