本文讨论了识别密闭空间中可能存在的危险，准确识别危险，管理危险，以及正确的进入程序。论文提到了进入受限空间前需要检测的四种主要危险，包括氧气、碳氢化合物、一氧化碳和硫化氢。讨论了测量空气中气体的仪器、进入过程的工具和设备，以及呼吸器的适当培训。

This paper discusses recognizing hazards that may be present in a confined space, identifying exactly what they are, managing them, and proper entry procedures. The paper mentions four primary hazards to test for before entering a confined space which include oxygen, hydrocarbons, carbon monoxide and hydrogen sulfide. Instruments that measure gasses in the air, entry process tools and equipment, and proper training for respirators are all discussed.