Patent ID: 9140631
Filing Date: 2015-09-22
Classification: G01N,Y10T

Abstract:
1. A method of measuring characteristics of a critical orifice type constant flow rate instrument applied to a dilution mechanism constructed in a manner that each of a plurality of dilution units is constructed such that a confluence is provided at an intermediate portion of a main flow passage connecting between an input terminal and an output terminal for leading input gas and a diluent gas flow passage provided with a flow rate controller is connected to the confluence so that diluent gas of a prescribed flow rate having a predetermined dilution ratio is introduced to the main flow passage and the plurality of dilution units are connected in series and at least one of the dilution units is provided with a branch point at the intermediate portion of the main flow passage so that a derivation flow passage provided with the critical orifice type constant flow rate instrument is connected to the branch point so as to derive the gas of a constant flow rate from the main flow passage, the method comprising: based on selective operation of a valving arrangement of the dilution mechanism, flowing the diluent gas from the diluent gas flow passage in the corresponding one dilution unit and the diluent gas from the diluent gas flow passages in one or more other dilution units to a derivation flow passage of one of the dilution units such that the total flow rate thereof is equal to the constant flow rate and that the flow rate of the diluent gas from the corresponding one dilution unit is equal to the prescribed flow rate; and measuring the flow rate characteristics of the corresponding critical orifice type constant flow rate instrument based on at least an upstream side pressure of the critical orifice type constant flow rate instrument in the corresponding derivation flow passage at this time.