When the valve is in the closed position, a sealing at the seat shall be accomplished by the contact between one edge of a securely retained elastomer quad seal and a smooth seat surface.

• 当阀门处于关闭状态，阀座上的密封应该完全由安全加固的合成橡胶方形密封边缘与光滑的阀座表面之间的接触来实现。