| 摘要 |
PURPOSE: To make it possible to select a material useful with respect to a thermal expansion coefficient with no need of taking account of corrosion protection, by making a corrosion-resisting cover surrounding the sleeves a gas-tight closing at the narcotic gas penetrating flow passage and by supporting the sleeves at the ends of the formed sides with the sleeve supports of the cover. CONSTITUTION: The formed bodies 9, 10 are sealed to a cover 14 by O-ring packings 12, 13. The simply-formed cover 14 to get a contact with a corrosive gas can easily be made to a corrosion protection, for instance, by the Ni-plating. Since the formed bodies 9, 10 forming a throttle gap 8 have no relation with the thermal compensation due to forming the throttle gap 8 to be met to the fluctuating temperature, the material for the formed bodies 9, 10 can be selected by taking account of the high corrosion protection and accurate productivity only. For the rods 15 being connected only at the ends opposite to the formed bodies 9, 10 with each other, brass can advantageously be used as a material of high thermal expansion coefficient, because the longitudinal expansion can sufficiently be used for exactly-variable gap width 9 due to simply being contact- supported by the sleeve supporters 20.
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