Patent ID: 9562858
Date: 2017-02-07
CPC Classifications: G01N

Claim:
1. A fluid concentration measuring device which measures concentration of a fluid flowing through a resin tube being light-transmissive, at least a portion of the resin tube having a continuous cylindrical tube wall being compressively deformable in a diametrical direction thereof, the device comprising: a light source which supplies light into the tube from a light supply part on a surface of the tube; a light receiving element which receives the light, which has been supplied and passed through the wall of the tube and the fluid inside the tube, at a light receiving part located on an opposite side in a diametrical direction of the tube relative to the light supply part, and outputs a signal indicating an intensity of the light; light path distance setting means which sets a plurality of light path distances between the light supply part and the light receiving part by compressively deforming the portion of the resin tube having the continuous cylindrical tube wall while holding the tube; and fluid concentration output means which, from the light intensity at the light receiving part located at each of the plurality of light path distances, obtains a plurality of relational expressions, which indicate relation between the light intensity and the fluid concentration when the light from the light supply part is received by the light receiving part over each of the light path distances, based on the Beer-Lambert law, and obtains the fluid concentration from the light intensity at the light receiving part based on the relational expressions for the plurality of light path distances and outputs the fluid concentration.