Calculating Oxygen Cylinder Duration

Planning Oxygen Usage

Determining How Long Your Oxygen Cylinder Will Last

Using the Cylinder Duration Formula

Estimating Oxygen Supply Time

• Step 1: Cylinder Pressure
• Locate the cylinder pressure (psi).
• Subtract a residual pressure of 200 psi to account for errors.
• Step 2: Cylinder Constant
• Refer to the cylinder constant values:
• "D" cylinder: Constant = 0.16
• "E" size: Constant = 0.28
• "M" size: Constant = 1.56
• "G" size: Constant = 2.41
• "H" and "K" size: Constant = 3.14
• Choose the constant based on your cylinder size.
• Step 3: Flow Rate
• Determine the flow rate in litres per minute.
• Typically, regulators provide a maximum of 15 litres per minute.
• Specialist applications may have higher flow rates (e.g., scuba diving, 25 litres per minute).
• Adjust the flow rate as needed (e.g., 6 litres per minute for a nasal cannula).
• Step 4: Calculate Duration
• Use the formula: (Tank pressure - Residual pressure) x Cylinder constant / Flow rate
• Calculate the time in minutes that the cylinder will last.

Example Calculation

Estimating Duration for a "D" Cylinder at 15 Litres Per Minute

• Step 1: (2000 psi - 200 psi) = 1800 psi
• Step 2: Cylinder Constant for "D" size = 0.16
• Step 3: Flow rate = 15 litres per minute
• Step 4: (1800 psi x 0.16) / 15 litres per minute = 19.2 minutes
• Estimated Duration: Approximately 19 minutes (rounded down)

Use this formula to calculate the duration of your oxygen cylinder based on your specific parameters.