类型21机械密封是初始设备制造商的工业标准。
The Type-21 mechanical seal is the industry standard for original equipment manufacturers.
标准“21型”机械式密封，有利于降低更换成本。
Mechanical seals are standard "Type 21" design for low replacement cost.
标准“21型”机械式密封，有利于降低更换成本。
Mechanical seals are standard "Type 21" design for low replacement cost.
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