公开(公告)号：US20200018736A1

公开(公告)日：2020-01-16

申请号：US16334848

申请日：2017-09-27

Applicant: FUJIKIN INCORPORATED

Inventor： Masaaki NAGASE ,  Kenji AIKAWA ,  Kaoru HIRATA ,  Takahiro IMAI ,  Tetsuo NARITOMI ,  Tsutomu SHINOHARA ,  Takahiro MATSUDA ,  Kouji NISHINO

IPC: G01N33/00 ,  G01F1/36 ,  G05D7/06

Abstract: A method for detecting the concentration of a specified gas contained in a mixed gas includes, in a pressure-type flow rate control device including a restriction portion, an upstream valve provided upstream of the restriction portion, and a pressure sensor for measuring the pressure between the restriction portion and the upstream valve, a step of flowing the mixed gas from the upstream side of the upstream valve in a state in which the pressure on the downstream side of the restriction portion is lower than the pressure on the upstream side of the restriction portion, a step of determining with a pressure sensor pressure drop characteristics occurring after the upstream valve is changed from an open to a closed state, and a step of determining the concentration of the specified gas in the mixed gas based on the pressure drop characteristics.