| 摘要 |
<p>A valve apparatus for solving a problem relating to fugitive emissions from sliding stem valves provides a valve body and a vertically extending, vertically slideable stem member that actuates a valving member between open flow and closed flow positions. The stem extends at generally right angles to the overall direction of flow through the valve body. A laterally extending valve bonnet is affixed in a sealable fashion to the valve body and forms a fluid tight seal over the valve stem. The end portion of the stem removed from the valving member carries a large magnetically moved piston which closely approximates the internal diameter of the bonnet. An external, preferable annular magnetic member slides between open flow and closed flow positions on the outside of the bonnet, its magnetic field sliding with the internal piston in order to open and close the valve. A valve position indicator or transmitter either indicates or transmits the position of the valving member at all times.</p> |
