In this type of valve, the sealing element resembles a large rubber doughnut that is mechanically squeezed inward to seal on either pipe (drill collars, drillpipe, casing, or tubing) or the openhole.

• 这种类型的阀门，其密封部件象一个大橡胶炸圈饼，机械地向内挤压，以密封管柱（钻铤、钻杆、套管或油管）或裸眼。