The O2 fail-safe activates at what O2 pressure?

The O2 fail-safe activates at what O2 pressure?

• A. 25 psig
• B. 15 psig
• C. 50 psig
• D. 10 psig

Answer: (A)

The main idea is that oxygen safety on anesthesia machines is pressure-triggered. The O2 fail-safe monitors the oxygen supply line pressure, and when that pressure falls to a preset threshold, the machine automatically reduces the flow of other gases (notably nitrous oxide) to prevent delivering a hypoxic mixture. That threshold is about 25 psig, so the fail-safe activates when O2 pressure drops to roughly 25 pounds per square inch gauge. In practice, the pipeline is around 50 psig, and as it falls toward 25 psig the system trims back non-oxygen gas flow and may alert you; if pressure continues to fall, it further limits gases to protect the patient. The other numbers listed aren’t used as the trigger in standard machines: 50 psig is the typical supply pressure, while 10 or 15 psig would be too low for a safe, practical threshold.

The main idea is that oxygen safety on anesthesia machines is pressure-triggered. The O2 fail-safe monitors the oxygen supply line pressure, and when that pressure falls to a preset threshold, the machine automatically reduces the flow of other gases (notably nitrous oxide) to prevent delivering a hypoxic mixture. That threshold is about 25 psig, so the fail-safe activates when O2 pressure drops to roughly 25 pounds per square inch gauge. In practice, the pipeline is around 50 psig, and as it falls toward 25 psig the system trims back non-oxygen gas flow and may alert you; if pressure continues to fall, it further limits gases to protect the patient. The other numbers listed aren’t used as the trigger in standard machines: 50 psig is the typical supply pressure, while 10 or 15 psig would be too low for a safe, practical threshold.