| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and inexpensive gas meter with a waterproof structure. SOLUTION: A vent channel with a labyrinth structure for carrying out ventilation between the outside and inside of a case 10 is made up of a front face of the case 10 which has an aperture 11b, and a rear face of a front cover 20 opposite to the front face. The labyrinth structure R is made up by engaging a recess 11d which is formed by a projection 11c disposed in the front face making up the vent channel, with a projection 27 disposed in the rear face of the front cover 20 opposite to the front face. COPYRIGHT: (C)2005,JPO&NCIPI
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