Thesis discusses a measuring system with a capillary leakage standard in which laminar flow
conditions of the measured gas are established. The physical starting points of the functioning
of the capillary leak standard are presented, on the basis of which we will derive the
equation for calculating the calibration constant of the capillary standard. A reference measurement
system is also presented, which measures the mass flow through the flow system.
Measurements were made at pressure drops from 0,4 to 2,4 kPa, on both capillary leakage
standards, which means a range of nitrogen flow rates from 0,04 to 2,4 mg/min. We calculated
the calibration constant that will be used for the inter-laboratory comparison of the
portable leak standard, we also calculated the calibration constant given from values given
on the calibration certificate and compared it with the calibration constant calculated from
the measurements. The deviation of the calibration constant of the larger and smaller capillary
standard is 1,4 % in 1,8 %, the expanded measurement uncertainty of the reference
meter is 0,2 %, the total expanded measurement uncertainty of the measurements performed
in this thesis is 0,38 %.
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