这种空压机气缸中基本上不含油，其活塞环和填料一般为聚四氟乙烯。

This kind of air compressor cylinder basically does not include any oil content in, the piston ring and packing is commonly ptfe.

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回填料采用机械运输，夯实采用蛙式夯机或立式夯机进行夯压，允许的情况下采用碾压机进行压实。

The backfill shall be transported with machine and rammed with a frog rammer or a vertical rammer, or rammed with a roller in case of allowable situation.

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回填料采用机械运输，夯实采用蛙式夯机或立式夯机进行夯压，允许的情况下采用碾压机进行压实。

The backfill shall be transported with machine and rammed with a frog rammer or a vertical rammer, or rammed with a roller in case of allowable situation.

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