Please specify separately coupling sets for iron valve extensions. 请单独说明用于铸铁阀门阀杆加长部件的连接装置。
The resiliency of the seal allows the valve body and disc to contract or expand, without the risk of jamming due to temperature fluctuations. 密封的弹性使得阀门阀体和阀瓣能够接触或扩张，避免了由于温度波动而产生堵塞的危险。
