danger confined space entry by permit only gas tester atmosphere pen and red danger tape placing on permit book

and atmosphere authorized background beware caution changing closed conditioner confine confined construction control danger defocused detector door emissions engineering environment equipment exhausting exit exploration flow geologist hands hanging health hole industrial industry inhale inside inspecting inspector machine machinery manhole occupational permit picture placing protection reduce restricted risk safe safety scientist security space sticker symbol test tester testing tunnel uniqueness ventilate ventilation warning worker working workplace