The grooves for double Oring seals are machined in the stem sheath of protective plastic for redundant stem leakage protection in conjunction with both the upper and lower bushings.

• 双重O形环密封槽经过机加工嵌入在保护塑料的阀杆护层内，防止多余的阀杆泄漏进入上部和下部衬套地连接位置中。