An toànCâu 331 / 360
Testing a sewer manhole, the meter shows the flammable gas reading as a percentage of the Lower Explosive Limit (LEL). Below what LEL reading does Cal/OSHA generally consider the flammable atmosphere acceptable for entry?
a.Below 50% of the LEL
b.Below 10% of the LEL
c.Below 90% of the LEL
d.Any reading is fine if oxygen is normal
Giải thích
Under Title 8 §5157, a flammable atmosphere is acceptable for entry only when combustible gas or vapor is below 10% of the Lower Explosive Limit. The LEL is the lowest concentration that can ignite, so the 10% margin provides a large safety buffer against explosion. Sewers can accumulate methane from decomposing waste, so continuous monitoring is essential.
Trích dẫn luật: Cal/OSHA Title 8 §5157Luyện miễn phí toàn bộ 360 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A plumber must enter a municipal sewer manhole to clear a blockage. Under Cal/OSHA §5157, why is this classified as a permit-required confined space?
- Before entering a sewer vault, a plumber lowers a multi-gas meter to test the atmosphere. In what order must the atmosphere be tested?
- A plumber's gas meter reads the oxygen level inside a sewer vault. What is the acceptable oxygen range for safe entry under Cal/OSHA?
- During a permit-required confined space entry into a sewer, Cal/OSHA requires an attendant. What is the attendant's primary role?
- A plumber notices a rotten-egg smell while opening a sewer cleanout, then the smell fades. What toxic gas is this most likely, and why is the fading smell dangerous?
- The atmosphere in a sewer vault tests as oxygen-deficient. Before any worker enters, what is the required corrective action?
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