Oxygen Tank Duration

Oxygen tank duration calculation approximates how much time is left in an oxygen tank based on oxygen flow settings.

Duration of Flow = Oxygen Tank Conversion Factor * Remaining Tank Pressure (psi) / Continuous Flow Rate (L/min)

Oxygen Cylinder Conversion Factors

• D Tank = 0.16
• E Tank = 0.28
• G Tank = 2.41
• H/K Tank = 3.14
• M tank = 1.56

Duration of Flow

Oxygen Duration Exam Questions

1. A size D cylinder of oxygen has a remaining pressure of 1200 psi. The patient’s flow rate is 3 L/min. When will the tank be completely empty?

A. 45 min
B. 1 hour 19 min
C. 1 hour 5 min
D. 1 hour 30 min

Answer: C.

2. A size G cylinder of oxygen has a remaining pressure of 2000 psi. The patient’s flow rate is 10 L/min. When will the tank be completely empty?

A. 10 hours 10 min
B. 9 hours 8 min
C. 8 hours 2 min
D. 5 hours

Answer: C.

3. Correctly match the Oxygen cylinder conversion factor to correct tank size.

A. D tank = 3.14,  E tank = 0.28, G tank = 2.41, H tank =  0.16
B. D tank = 0.16,  E tank = 0.28, G tank = 2.41, H tank = 3.14
C. D tank = 0.28, E tank = 0.16, G tank = 3.14, H tank = 2.41
D. D tank = 0.16, E tank = 2.41, G tank = 0.28, H tank = 3.14

Answer: B.

4. A patient states his E tank cylinder only lasted 1 hour at a flow rate of 2LPM. What psi of oxygen was in his tank?

A. 1000 psi
B. 378 psi
C. 429 psi
D. 1240 psi

Answer: C.

Liquid Oxygen Duration Test Questions:

• Duration: Oxygen remaining in liquid O₂ cylinder in min
• Capacity: Liquid O₂ in cylinder in L
• Factor to convert liquid to gaseous O₂
• Reading on cylinder (example 0.33)
• Flow: O₂ flow rate L/min

1. The liquid capacity of a home liquid oxygen system is 40 Litres. The home care patient uses the system for 8 hours during sleep at a flow of 3 L/min. How many days with the home oxygen system last?

A. 24 days
B. 29 days 
C. 42 days 
D. 12 days

Answer: A.

2. If the capacity of a liquid oxygen cylinder in 4.0 L and the reading on the gauge is ⅓ full. How long with the liquid oxygen last if the flow is at 2 L/min.

A. 567 min
B. 766 min
C. 340 min
D. 102 min

Answer: A.