Balanced bellows seals may be required instead of conventional type due to process fluid considerations. Pilot operated valves are acceptable in place of bellows type for clean services.是什么意思_Balanced bellows seals may be required instead of conventional type due to process fluid considerations. Pilot operated valves are acceptable in place of bellows type for clean services.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句