An oxygen E cylinder contains 625 liters. Approximately 560 liters are deliverable. If the total gas consumption is 7 L/min, how long will the supply last?

An oxygen E cylinder contains 625 liters. Approximately 560 liters are deliverable. If the total gas consumption is 7 L/min, how long will the supply last?

• A. 60 min
• B. 80 min
• C. 100 min
• D. 120 min

Answer: (B)

The amount of time the oxygen will last is found by dividing the usable gas volume by the flow rate. Here, about 560 liters are deliverable, and the consumption is 7 liters per minute. So the duration is 560 ÷ 7 = 80 minutes. Note that using the total cylinder volume (625 liters) would give a longer time, but not all of that gas is deliverable due to pressure and regulator considerations; the usable amount is the correct value to use for this calculation.

The amount of time the oxygen will last is found by dividing the usable gas volume by the flow rate. Here, about 560 liters are deliverable, and the consumption is 7 liters per minute. So the duration is 560 ÷ 7 = 80 minutes.

Note that using the total cylinder volume (625 liters) would give a longer time, but not all of that gas is deliverable due to pressure and regulator considerations; the usable amount is the correct value to use for this calculation.