又称监测井，是地浸系统中用于监测地下流体动态的钻孔。主要用来观察地下流体的水位和铀的浸出情况，监测溶浸范围，监视地下水的污染状况等。对于一个采用地浸法浸出的井场，一般应在浸出区、井场边界和沿地下水流方向布置一定数量的监测孔。
n. sightglass
炉墙上设有人孔门、观察孔和测量孔。
Manhole, observation hole and measure hole are set on the wall.
用于油位计、观察孔等的材料，好使用天然玻璃或聚酰胺材料。
For the oil level gauge, observation hole and the best use of natural materials, glass or polyamide materials.
焊接熔观察孔针(3)设置在管件本体上，方便检测焊接进程，控制焊接质量。
The molten observation hole needle (3) is arranged on the pipe fitting body so that a welding progress can be conveniently detected, and the welding quality can be controlled.
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