Packing: PTFE or graphite packing protected from freezing by a column of insulating gas.填料：通过绝缘气体柱防止PTFE或石墨填料冻结凝固。
Packing: Teflon or graphite packing protected from low temperatures by a column of insulating gas.填料：通过保温绝缘气体来保护聚四氟乙烯或石墨免受低温影响。