How does oxygen concentrator work?

The main component in the air

• Nitrogen – 78%
• Oxygen – 21%
• Other – 1%

How to change the percentage in the air we breathe by using Oxygen Concentrator?

Normal air contains only 21% oxygen we need to either add or remove something from the air to improve the ability of the patient’s lungs to function. The easiest way is to remove the largest element from the mix. If we remove all of the nitrogen we are left with oxygen and small amounts of other elements (primarily argon, an inert gas).

With nitrogen gone (78% of the air we started with) the percentage of oxygen (which was 21%) and ‘other’ (which was 1%) now become:

• Oxygen – 95%
• ‘Other’ – 5%

What this is ultimately stating is that the maximum oxygen concentration we can get by removing nitrogen from the air is around 95%. This is important to note when comparing products. None can give more than this percentage but an inefficient design can surely give less.

Oxygen Therapy for Patients

While the above elements work well for people with normal lung functioning, patients with COPD need a stronger concentration of oxygen when they inhale. There are several ways to accomplish this goal:

• Oxygen Generators (concentrators)
• High pressure oxygen tanks

The source of pure oxygen rely on a regular, steady supply to be delivered to the patient’s home.

Only oxygen concentrators have the capability to create the proper amount of oxygen without outside services.

How Nitrogen is removed from the air

Methods were found that reliably separate specific gas elements. One of these has been adopted for most oxygen concentration systems. PSA (Pressure Swing Adsorption) causes this separation to occur using pressure, as the name implies. Pressure alone doesn’t perform the magic. A special material was also developed to do the hard work. This material is called Zeolite and is actually a microscopic cube with holes on all six sides. Nitrogen molecules chemically bond to its surfaces as they pass through; letting only Oxygen and ‘Other’ elements flow through unimpeded.

The Zeolite is housed in air tight cylinders called ‘sieve beds’. Most oxygen concentrators use two of these ‘beds’ (more on that later). Of course, once the Zeolite has adsorbed its maximum load of Nitrogen molecules it can’t stop the rest of the Nitrogen from passing through.

Oxygen Concentrator

Major Components:

The operation of the entire machine is controlled by a microprocessor. The only (normally) operator settable characteristic is output flow (settings of 1 through 5 ).

Most units include some visual and audible alarms (low oxygen, battery failure, etc.)

PSA Process

The following is a simplistic explanation of the Pressure Swing Adsorption process used in oxygen concentrators:

1. Room air is pulled in through the inlet filter by the inlet side of the compressor.
2. The air is compressed and forced into sieve bed A (‘charge’ cycle)
3. Oxygen is forced through the sieve bed into the Product Tank
4. After several seconds sieve bed A becomes saturated (full) of Nitrogen
5. The switching valves reroute the gas flow:

1. Compressed air is now forced into Sieve Bed B
2. Sieve Bed A inlet (compressor) side is ‘ported’ to atmosphere (the room)
3. A small amount of pure (95%) oxygen from the product tank flows backward into Sieve Bed A
   1.                                                          i.            The combination of pressure drop in Sieve Bed A (we just opened it to atmosphere) and the backflow of pure oxygen cause the Zewolite to release the captured Nitrogen molecules. The Oxygen and Nitrogen remix and enter the room as ‘normal’ air.

The air is compressed and forced into sieve bed B (‘charge’ cycle)

Oxygen is forced through the sieve bed into the Product Tank

After several seconds the cycle repeats with Sieve Bed A