Oxygen Tank Duration
Calculate how long an oxygen tank lasts based on tank size, pressure in PSIG, and flow rate in L/min. Free O2 duration calculator with comparison charts.
About This Calculator
The Oxygen Tank Duration Calculator estimates how long an oxygen cylinder will last based on its size, internal pressure, and the prescribed flow rate. This tool is essential for healthcare facilities, home oxygen therapy patients, respiratory therapists, emergency medical services (EMS), and anyone needing to plan oxygen usage for medical or industrial applications.
The calculation uses the standard formula: Tank Duration (minutes) = PSIG × Conversion Factor / Flow Rate. Each tank size has a specific conversion factor derived from its gas capacity. For example, a size E tank (680 L capacity) has a conversion factor of 0.28, a size D tank (340 L) has 0.16, and a size K tank (7100 L) has 3.55. Simply multiply the tank pressure in PSIG by the conversion factor, then divide by the flow rate in L/min to get the duration in minutes.
Regional Notes
India: Medical oxygen cylinders in India follow the same international sizing standards (B-type ≈ D, D-type ≈ E). Pressure gauges typically read in bar or kg/cm² (1 bar ≈ 14.5 PSIG). Flow meters are calibrated in L/min. Common hospital sizes are D and E cylinders.
US: Oxygen cylinders are regulated by the FDA and DOT. The E cylinder is the most common portable size for home oxygen therapy. Home concentrators typically deliver 1-5 L/min continuous flow. Always consult a respiratory therapist for appropriate flow settings.
UK: The NHS provides oxygen cylinders in sizes C, D, E, and F for home use. Pressure is typically measured in bar (1 bar ≈ 14.5 PSI). Flow rates are prescribed in L/min by a respiratory consultant or GP. Always follow your clinician's prescribed flow rate.
Frequently Asked Questions
How does the oxygen tank duration calculator work?
The oxygen tank duration calculator uses the formula: Duration (minutes) = PSIG × Conversion Factor / Flow Rate. Select your tank size, enter the pressure in PSIG and the flow rate in L/min, and the calculator instantly shows how long the oxygen will last.
What is the oxygen tank duration formula?
The formula is Tank Duration = PSIG × Conversion Factor / Flow Rate. The conversion factor depends on tank size: C (0.085), D (0.16), E (0.28), F (0.68), M (1.56), G (1.7), H (3.14), J (3.4), and K (3.55).
What tank sizes are available for oxygen cylinders?
Common oxygen tank sizes are C (170 L), D (340 L), E (680 L), F (1360 L), M (3200 L), G (4100 L), H (6600 L), J (6800 L), and K (7100 L). Each size has a specific conversion factor used in the duration formula.
How long does a size E oxygen tank last at 3 L/min?
A size E oxygen tank (680 L capacity, conversion factor 0.28) at 5500 PSIG and 3 L/min flow rate lasts approximately 513 minutes or about 8.6 hours.
Is oxygen tank duration the same as flow rate?
No. Oxygen tank duration is the total time the oxygen in the tank lasts based on size, pressure, and flow rate. Flow rate is the speed at which oxygen flows from the tank measured in liters per minute (L/min).
How can I calculate oxygen tank duration manually?
To calculate manually: 1) Note the tank size and find its conversion factor from a chart. 2) Multiply the conversion factor by the pressure in PSIG. 3) Divide the result by the flow rate in L/min. The answer is the duration in minutes.
What pressure units can I use?
This calculator uses PSIG (pounds per square inch gauge). Most medical oxygen gauges in the US display PSIG, while India and the UK often display in bar (1 bar ≈ 14.5 PSI). Convert bar to PSIG by multiplying by 14.5 before entering the value.
Why are conversion factors different for each tank size?
Conversion factors account for the tank's gas capacity at standard pressure. Larger tanks store more gas at the same pressure, so they have a higher conversion factor, resulting in longer duration. The factor is derived from the tank's water capacity and service pressure.