Liquid level may drop but as minimum water column of 28 inches (1.0 PSI) (6.89 kPa) or greater should be maintained when the check module is operating correctly.是什么意思_Liquid level may drop but as minimum water column of 28 inches (1.0 PSI) (6.89 kPa) or greater should be maintained when the check module is operating correctly.在线翻译_英语_读音_用法_例句