Primary stop valve

The utility model relates to the technical field of mechanical sealing, and provides a first-stage stop valve which comprises a valve body, a second-stage stop valve, a first stop valve body, a second stop valve body, a third stop valve body and a fourth stop valve body, and the first stop valve body is provided with a first channel and a second channel which are intersected and communicated with each other and is suitable for being sleeved on a stirring shaft through the first channel; the stopping mechanism is arranged in the second channel in a sealed mode and comprises two holding assemblies, and the two holding assemblies are oppositely arranged on the two radial sides of the stirring shaft so as to hold and seal or loosen the stirring shaft. The sealing device has the characteristics of convenience in use, good sealing performance and the like. 本实用新型涉及机械密封技术领域，提供了一种一级截止阀，包括：阀体，所述阀体设有相交且连通的第一通道和第二通道，所述阀体适于经所述第一通道套设于搅拌轴；截止机构，所述截止机构密封设置于所述第二通道内，包括两个抱紧组件，所述两个抱紧组件相对设置于所述搅拌轴径向的两侧，以抱紧密封或松开所述搅拌轴。本实用新型具有使用方便、密封性