OXYGEN CYLINDERS - How Long Do They last

Anyone who uses an oxygen cylinder should be aware of its basic characteristics, so as to be able to use it correctly.

This is specially true of oxygen therapy patients who must make sure of their blood oxygenation.

It is also important that you know, both for normal oxygen therapy and for emergencies, how much oxygen is stored in your cylinder and how long the supply will last.

How To Calculate The Duration Of Our Tanks

The consumption of O2

First of all you need to know how much oxygen should be administered as per your prescription, in other words your oxygen flow rate.

This obviously has to be based on the oxygen flow prescription, which in turn should be according to the doctor´s instructions.

That flow, how much oxygen per minute, measured as liters per minute, will be the starting point for your calculation.

Next is the size of the cylinder.

These are identified by letters: A, B, C, D and E. A being the smallest and so on.

The more popular sizes are B and E Cylinders.

To complicate matters there is also another set of names to identify cylinder sizes. These start with the letter M, which refers to "medical" oxygen use. The M is followed by a number that indicates the cubic feet. So an M6 cylinder is a medical oxygen cylinder that can store 6 cubic feet.

So what? you may ask, and I couldn't agree more.

So to make this simpler, after all you only want to find out how much oxygen you have left, the following is a table to help you calculate how much oxygen you have left at a constant flow rate:

The important parts of this table for you are the Size and the Factor. Note: The last column shows how long oxygen will last when the cylinder is full (2200 psi) at a constant flow rate of 1 liter per minute.

  As an example, suppose you have an E cylinder, that has a psi of 1800 and your flow rate (constant) is 3.

 The factor for E cylinders is 0.28. Psi is 1800 and your Flow rate is 3.

a. Multiply 1800 (your Psi) by 0.28 (x factor for E cylinder) and you get: 504
b. Divide 504 by your flow rate: 3, and you get: 168
c. You have 168 minutes of oxygen left (2 hours 46 minutes).

The formula: PSI x Factor / Flow Rate = Minutes of oxygen left.

 

• Oxygen cylinder sizes.
• How much oxygen is stored in the cylinder - (The pressurized oxygen capacity of an aluminum cylinder and a composite one will differ). 
• • How much oxygen is left in the cylinder.
  • The flow rate, and if you have continuous flow or pulse flow delivery.

If you use an oxygen regulator, whether pulse or pneumatic, the oxygen will last much longer as you are not wasting oxygen as happens with a continuous flow (the oxygen is still delivered when you exhale).

Aluminum oxygen Cylinders and Composite Oxygen Cylinders.

Oxygen cylinders are either aluminum or composite. The difference from the point of view of the user is the amount of compressed oxygen they hold.

Carbon-composite cylinders are lighter that aluminum cylinders which make carrying and mobility easier for patients on supplemental oxygen and can hold up to 30% more oxygen. As oxygen gas is compressed into the cylinder this pressure, known as psi (pounds per square inch) is the guiding figure to how much oxygen is stored. Aluminum tanks are generally compressed up to 2200 psi; composite cylinders to 3000 psi.