| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a flow rate sensor from being stained and deteriorated in sensor efficiency in a long-time use. SOLUTION: The apparatus is provided with a main conduit 3, a porous orifice plate 5 reducing a flow of a burning gas flowing in the main conduit 3, a branch passage 11 having opening parts 8 at the upstream and downstream side of the porous orifice plate 5 and communicating the opening parts 8 with each other, a microflow sensor 12 set in the branch passage 11, and an orifice plate 13 reducing the flow of the burning gas running in the branch passage 11. Even a minute flow rate of the burning gas such as a town gas, an LPG or the like which often pollutes the interior of a piping with dust and oil mist, etc., can be measured at high response speed with high accuracy. A change with time of the microflow sensor 12 can be effectively prevented.</p> |
