Valves shall have glass-filled PTFE seals for positive shut-off and extended service-life and FPM seals for maximum protection against external leakage.

• 这种阀门应该配置玻璃填充聚四氟乙烯密封，关闭更加灵活，使用寿命更长，FPM密封能够更好的防止外泄漏。