Which of the following statements is true...

🔍 Key Concepts

• Tank atmosphere stratification – how oxygen and other gases can form layers at different heights in a confined space • Indicator limitations and contamination – what can affect the accuracy of an oxygen indicator over time • Safe entry criteria – what oxygen percentage is normally required before entering a confined space

💭 Think About

• Think about whether sampling only from the bottom of a tank will tell you what the air is like at all levels where a person might breathe. • Consider what can cause an oxygen indicator to give a false reading after it has been exposed to certain gases over time. • Recall the typical safe oxygen percentage range for human entry into confined spaces. Is 14% within that accepted safe range?

✅ Before You Answer

• Verify the required safe oxygen range for confined space entry (minimum percentage). • Check whether sampling procedures call for testing at multiple levels (top, middle, bottom) rather than a single point. • Confirm whether manufacturers warn that prolonged exposure to other gases (like CO₂) can affect sensor accuracy.

Which of the following statements is true regarding oxygen indicators?

A gas sample should only be taken from the lowest portion of the tank to test for oxygen.

Prolonged exposure to gases such as CO₂ may affect the accuracy of the indicator.

An oxygen reading of 14% is considered safe for entering.

All of the above.

🔍 Key Concepts

💭 Think About

✅ Before You Answer