Patent ID: 6964190

Claim:
In a particulate matter concentration measuring apparatus for measuring a concentration of particulate matter in a sample gas collected in a collecting region formed on a collecting member, the collecting region being formed by drawing the sample gas through a cross-sectional area of the collecting member from one face side to the other face side, the improvement comprising: the collecting member is a filter tape, the filter tape includes a porous film made of a fluorine resin for trapping particulate matter in the collecting region, the filter tape includes a reinforcing layer of a non-woven fabric on the porous film, the reinforcing layer allows the transmission of the sample gas; and a supporting means for supporting the filter tape in the collecting region, the supporting means having a plurality of exhaust holes for discharging the sample gas passing through the filter tape and supporting the filter tape against being deformed in the collecting region, the support means having at least four exhaust holes, the exhaust holes being disposed with approximately circular symmetry around a predetermined central position, wherein the supporting means includes a first clamping means and a second clamping means which move together to securely hold the filter tape at a time of collecting the particulate matter while permitting the passage of the sample gas through the filter tape, the first clamping means and second clamping means being moved apart so as to release the filter tape at a time of moving the filter tape.