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GENERAL INFORMATION

Clinical oxygen can be delivered to oxygen patients by a variety of medical devices described by the following technical and non-technical terms: oxygen concentrators, home oxygen concentrators, oxygen condenser, oxygen maker, portable oxygen concentrators (often described as a POC), liquid oxygen, oxygen generator, oxygen tank, oxygen bottle, and oxygen cylinder.  Use of non-technical terms to describe clinical oxygen sources implies more modes of oxygen delivery than actually exist.  In reality, clinical oxygen can be delivered by only three methods or modes. 

Clinical oxygen is typically delivered by the following modes:  oxygen concentrator (including POC), liquid oxygen, and high pressure oxygen cylinders. 

The terms oxygen maker and oxygen condenser are often used interchangeably when the device being described is an oxygen concentrator. High pressure oxygen cylinder is the correct term for oxygen tank, oxygen bottle, and oxygen cylinder.   Liquid oxygen is a correct term describing the cryogenic fluid form of oxygen, o2, more on that one later.  The device described as an oxygen generator is not used in the clinical setting.  

Liberty Medical rents and sells new and used home oxygen concentrators.

Each oxygen delivery mode has strengths and weaknesses, and represents a compromise of size, weight, and duration.  Advancements in technology have improved the versatility of the three most common delivery modes, oxygen concentrators, high pressure oxygen cylinders and liquid oxygen systems. 

The oxygen concentrator, home oxygen concentrator, and POC are probably the most common oxygen sources used.  These systems come in a wide range of oxygen liter flows and physical sizes to fit most clinical oxygen applications.   As is common with most electrical mechanical devices, the smaller and lighter oxygen concentrators will have lower liter per minute flow capacities. 

Oxygen concentrators gather from the air, or concentrates, oxygen (o2), using a process technically described as pressure swing absorption (PSA).  Briefly, air is moved using a small compressor at low pressures, typically less than 20 PSI, into a vessel containing a catalyst commonly called zeolite which causes the molecules of nitrogen (n2), to stick to (photo) the catalyst but does not affect the molecules of oxygen, which are allowed to pass and are collected and delivered to the oxygen patients.  The catalyst looks and feels much like sand and is contained within a group of  vessels, usually two or more, commonly described as beds or sieve beds.  

You may have been around an oxygen concentrator and noticed a venting sound every now and again.  Often this venting sound will occur at identical intervals of 10 or 15 seconds.  The venting sound is the purging of a sieve bed and is typical to all oxygen concentrators. 

Home oxygen concentrators can be quite large, heavy (often in excess of 50 lbs), noisy , power hungry, and can easily heat a bedroom.  These systems are probably the most common source for home oxygen.  Their durability make them the first choice for home oxygen users.  Powered by any standard 120 volt AC wall outlet, the home oxygen concentrator works well anywhere in the USA.

A better choice:  Liberty Medical has the Respironics EverFlo home oxygen concentrator (photo) available to rent or for sale both new and used.  The same versatility and reliability of home concentrators but smaller, quieter, and less intrusive.  The EverFlo weighs just over 30 lbs, is compact, quiet, and a better choice

The portable oxygen concentrator or POC is a relatively new product incorporating all the best technologies of the PSA home oxygen concentrator with the latest advancements in rechargeable lithium ion battery technology.  (photo) POC such as the Inogen One, Respironics  EverGo ,and SeQual Eclipse 3 all use the lithium rechargeable batteries to allow oxygen patients to gain unprecedented freedom.  With the acceptance of the Inogen One, Respironics EverGo and SeQual Eclipse 3 by the Federal Aviation Administration (FAA), oxygen patients are able to more easily fly anywhere.

High pressure oxygen cylinders preceded oxygen concentrators, POC, and all other forms of home oxygen.  High pressure oxygen cylinders are not FAA approved, and cannot be taken onboard commercial flights. 

Today high pressure oxygen cylinders are the mainstay in ambulatory oxygen. Systems range from the large, 30 inch tall, size E (photo) cylinder to the compact and versatile B (photo) cylinder.  Most steel oxygen cylinders have long ago been retired and replaced with aluminum.  Weights ranging from 15 pounds for an aluminum size E cylinder which holds 680 liters of oxygen when filled to 2,000 PSI down to the 5 pound  B cylinder holding 164 liter of oxygen when filled to 2,000 PSI.  Larger cylinders, size D and E, are typically mounted on two wheel carts for easier mobility.  The smaller cylinders, sizes C and B typically can be carried in a shoulder bag, back pack, or belly pack

Advancements in oxygen regulators, the cylinder top device which controls the oxygen flow out of the cylinder, increase the efficiency of the cylinder system allowing many patients to have increased mobility.  These same advancements became the springboard for the demand controllers used on the Inogen One, Respironics EverGo and SeQual Eclipse 3 POC systems. 

Liberty Medical sells high pressure oxygen cylinder systems using the more advanced Chad Oxymatic 400 series conserving regulators.

Liquid oxygen is not FAA approved and cannot be taken onboard commercial flights. Liquid oxygen is a super cooled form of oxygen.  Through a compression and cooling process, air is caused to liquefy (getting really, really cold), oxygen is separated off and distributed in the liquid form.   Liquid oxygen can be a great source for home oxygen and for ambulatory systems.  Liquid vessels must be kept up-right as they vent oxygen even when turned off. 

Oxygen generators or chemical oxygen generators are the forgotten oxygen source.  Not widely used, nor FAA approved for use by respiratory oxygen patients, these devices were once widely used as a source of emergency oxygen on commercial aircraft.  Chemical oxygen generators are exothermic and can be a fire hazard if not properly handled.