US 12,449,353 B2
NDIR gas measuring device for detecting presence of gas other than measurement target gas
Cheol Woo Nam, Daegu (KR); Byung Yul Moon, Daegu (KR); Eung Yul Kim, Daegu (KR); Jae Hwan Kim, Daegu (KR); Chun Ho Shin, Daegu (KR); Kwang Hun Park, Daegu (KR); Myun Gu Choi, Daegu (KR); Chang Hwang Choi, Daegu (KR); Yong Geol Kim, Daegu (KR); and Jae Min Jeon, Daegu (KR)
Assigned to SESUNG INC., Daegu (KR)
Filed by SESUNG INC., Daegu (KR)
Filed on Sep. 8, 2023, as Appl. No. 18/244,045.
Claims priority of application No. 10-2022-0128594 (KR), filed on Oct. 7, 2022.
Prior Publication US 2024/0118196 A1, Apr. 11, 2024
Int. Cl. G01N 21/3504 (2014.01); G01N 21/03 (2006.01); G01N 21/05 (2006.01)
CPC G01N 21/3504 (2013.01) [G01N 21/05 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A non-dispersive infrared gas measuring device comprising:
a gas cell;
an infrared light source configured to measure absorbance by a sample gas inside the gas cell and radiate infrared light into the gas cell; and
a measuring unit configured to measure an amount of light absorbed at a specific wavelength by the sample gas when the radiated infrared light passes through the sample gas filling the gas cell,
wherein, in the gas cell, in order to increase absorbance by the sample gas, the infrared light emitted from the infrared light source is repeatedly reflected laterally by mirrors provided at both end portions of the gas cell and then reaches the measuring unit, five optical band-pass filters configured to measure measurement target gases of interest are provided at a front end portion of the measuring unit, and optical five broad band-pass filters, which have different optical wavelength bands of 3 μm to 13 μm (A), 4 μm to 13 μm (B), 5 μm to 13 μm (C), 7 μm to 13 μm (D), and 8.5 μm to 13 μm (E) which overlap each other from a longest wavelength to a shortest wavelength of the infrared light source, are provided to identify whether there is a gas other than the measurement target gases of interest so that magnitudes of signals of broadband optical band-pass filters which are closest to each other are compared to calculate a magnitude of absorbance generated in a non-overlapping region, a greater magnitude of the absorbance in the non-overlapping region indicates that other gases are present, the magnitude of the absorbance is compared with a magnitude of absorbance for each wavelength band according to types of the other gases to select a type of gas with a large absorption signal as a candidate gas included in the sample gas, and an absorption ratio is checked according to various combinations of the broadband optical band-pass filters excluding overlapping parts in other regions to virtually combine changes in absorbance according to a concentration of a mixed gas and accurately measure a type and concentration of gas from an NDIR measurement signal of the measured sample gas.