COPD Oxygen Therapy Systems: Container/Storage & Delivery Systems
Stationary Systems continued...
Another stationary system is a reservoir for liquid oxygen. Liquid oxygen is gas condensed into a liquid state by extreme cold. Liquid systems have a large reservoir tank. This tank is filled by the oxygen supplier once or twice a month. These systems require no electricity. They have very few moving parts. They require little maintenance or repair. When dealing with liquid oxygen, caution must be exercised to prevent spills. Liquid oxygen is very cold. It can injure the skin instantly upon contact.
A typical liquid oxygen reservoir weighs 124 pounds when filled. It contains 31 liters, or 73 pounds, of liquid. This amount of liquid oxygen is the same as 24,950 liters of oxygen in the gas form. At a flow rate of two liters per minute, this amount of oxygen would last 208 hours, or eight days. Liquid systems constantly lose oxygen through evaporation, even when not in use. So they are suitable for regular use at home, or for filling up portable units. They are not suitable as an emergency back-up system. Newer units are now available that reduce the amount of oxygen lost into the air. These new systems also have improvements in size and stability. Many of these systems have built-in pulsed delivery or conserving devices.
Compressed gas oxygen in large tanks or cylinders is another example of a stationary system.
Large steel or aluminum tanks are heavy. They cannot be moved easily. They must be safely secured to prevent them from falling over. They are not appropriate for someone who requires continuous flow oxygen. This is because of the volume required to meet a continuous need and the high cost.
This system is better suited as a back-up system for a concentrator.
Oxygen concentrators were once thought of only for patients who were homebound and inactive. Newer and lighter-weight models have been developed for portable use. They have electrical connections for cars. They are also outfitted with battery packs. There are even newer concentrators that fill portable cylinders at home, provide accessibility and convenience. This type of concentrator compresses oxygen to fill the cylinders. And it also provides continuous-flow oxygen for breathing.
Small portable liquid oxygen units can be easily filled from the large liquid reservoirs using a direct link between the two. A small portable unit that has a conserving device can allow you to spend longer periods away from home. This will promote a more active lifestyle. This combo of a portable unit/conserving device also can serve as a base reservoir that can be filled less often.
Compressed gas in smaller cylinders can provide portability as well.
Below is the approximate time a cylinder would last at a rate of two liters per minute without a conserving device. If a conserving device is used, these time frames would be extended:
- E-cylinder: up to five hours
- D-cylinder: up to three hours
- M9: up to two hours
- M6: up to one hour