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Oxygen Concentrator:-Type, Application, Working Mechanism, Maintenance

An oxygen concentrator is a part of an oxygen delivery system that is used to extract and supply oxygen gas directly from the environment. This is possible with the help of the zeolite tower controlled by the solenoid valve. 

It is similar to an oxygen cylinder with some differences.

Oxygen Concentrator Vs Oxygen Cylinder

Oxygen Concentrator Oxygen Cylinder
Needs ac supply for operation Does not need any power supply
Weight ranges from about 5 to 50 kg Weight ranges up to 50 kg or more
It has got low oxygen pressure. So, the flow rate is also low compared to an oxygen cylinder. It has got high oxygen pressure. So, the flow rate is also high.
Works for 24 hrs. No need for refilling Needs to refill the cylinder once it is empty.
Has got a wheel in it. Thus, it easier to transport from one room to another Does not have a wheel in it. Thus, it is not easy for transportation (Steel-type)

If you need oxygen for a few days, you may buy only an oxygen cylinder. Else buying an oxygen concentrator will be more economical for you.

If you need to use an oxygen concentrator you will have to buy an oxygen cylinder for a backup. You may need the oxygen cylinder in case of the 

  • power failure in your house
  • malfunctioning of the concentrator

Household Oxygen Concentrator Vs Portable Oxygen Concentrator

Household Oxygen Concentrator

Portable Oxygen Concentrator

Normally weighs from 20- 24 kg

Normally weighs around 6 kg

Cheaper

Quite expensive

Has got wheels at the base. Thus you can move it easily from one room to another

Can even be carried on like a bag while going outside

Flowrate can range up to 10 liters/min (based on the models)

Flowrate can range up to 5 liters/min (based on models)

Single or dual patients (based on models)

For single patient

Operates on AC 220 Volt with no battery backup

Operates on AC 220V and can have battery backup

Delivers around 90% – 96% oxygen purity

Delivers around 38% -90% oxygen purity

Applications of Portable Oxygen Concentrator

  • While going outside for shopping, traveling, etc.
  • Mental worker and student recover energy
  • Pregnant women
  • Oxygen cocktail making

Who needs an Oxygen Concentrator?

It is mainly needed for COPD and hypoxia patients.

Handling of the Oxygen Concentrator

  • The oxygen concentrator produces a high amount of oxygen. Oxygen helps in rapid burning. So, you should not place the machine near the fire/ kitchen. Similarly, smoking, use of petroleum products, lubricants, grease, etc, should not be allowed near the machine.
  • Operate the machine in an open space. Maintain a gap of at least 2 feet between the machine and the wall of the room.
  • Place the machine on the floor. Do not place it on top of the table, bed, etc. Else, the machine might fall due to the vibration created by the compressor of the machine. 
  • Keep the machine in a clean environment. This will increase the life span of the machine.
  • Clean the humidifier bottle with clean water. I recommend you not to use tap or filtered water in the bottle. Instead of that, you can buy distilled water from the market. 
  • In the case of any problem with the machine, consult with the service engineer. Do not open the machine on your own.

Components of the Oxygen Concentrator

  • Compressor
  • Sieve Bed (Zeolite Tower)
  • Filters
  • Tubes
  • Four-Way Directional Valve (Solenoid Valve)
  • Cooling Fans
  • Pressure Sensor and Pressure Regulator
  • Accumulator Tank (Oxygen Tank)
  • Flow Meter (Rotameter)

Working Mechanism 

Block Diagram of Oxygen Concentrator

First of all, air from the atmosphere goes inside the compressor through the filters. The piston inside the compressor will pressurize the incoming air and sends it to the four-way directional valve. This pressurized air will release heat. So to cool it down, a cooling fan is used. Through the valve pressurized air goes to one of the sieve beds. The sieve bed consists of zeolite powder which allows oxygen to pass through it. The pressure in the sieve bed is analyzed by the circuit board. When certain pressure is reached, the circuit board allows four-way directional valves (solenoid valve) to change the direction of airflow. Now the air goes to the other sieve bed for filtration. While this process is going on, the other sieve bed will depressurize and gases such as nitrogen and water vapor will release back to the atmosphere. You need two sieve beds so that they can supply oxygen continuously.

Filtered dry oxygen will then accumulate in the accumulator tank. It consists of a dial pressure gauze and a pressure sensor. The pressure sensor is used for safety purposes i.e. when the oxygen reservoir becomes full then the air compressor stops working. From the accumulator tank, some amount of oxygen goes through the circuit board to check its purity. A major portion of the oxygen goes through the rotameter. It helps to regulate the amount of oxygen output. Then it comes out of the machine at a controlled rate through a humidifier.

Reasons for the vibration of the oxygen concentrator

You need to be careful about the noise that your concentrator makes. This is because it will give you an idea about the current situation of your machine.  Some of the reasons could be because of the:

  • Age of your machine
  • Low voltage from the power supply. The compressor will have difficulty operating.
  • Air leakage from the pipes or the solenoid valves.

Maintenance of Oxygen Concentrator

(Factors affecting the output of the oxygen concentrator)

  • Check the output of the concentrator with the help of an oxygen analyzer or you can also use the pulse oximeter.

1. Machine does not operate

If the machine does not turn on, then it can be because of the malfunctioning of the power cord, switch, fuse, or mainboard. If such a problem occurs, then make sure to replace the malfunctioned part.

Generally, you will find 3-5 A fuse. Similarly, the switch will be of 4- pins. You can check the continuity of the switch. But, I recommend you to cross-check it with a new one, instead of fully trusting the multimeter.

2. Filters

You will find two types of air filters in the oxygen concentrator. The outer dust filter filters the dust particles. It also protects the inner HEPA filter. You can clean this filter with soap and water. 

You need to replace the HEPA filter periodically (at least twice a year).

3. Zeolite Tower (Sieve Bed)

Sieve Bed / Zeolite Tower, Oxygen Concentrator
Image Source:-https://cubro.co.nz/products/parts/sieve-bed-assembly-including-valve-module-and-zz0811004

A pair of zeolite towers lies within the concentrator. After continuous use of the concentrator, the effectiveness of the tower keeps on decreasing. Lumps of the zeolite may be formed within the tower. Besides that, there can be leakage at the outer layer of the zeolite tower. So, you to cross-check the zeolite tower in that case.

4. Tubing

There are several flexible tubing inside the concentrator.  Due to the high pressure of air, friction developed within the machine, the tubes may rupture. Thus, in that case, there might be air leakage. So, you need to replace the tubes in that case.

5. Compressor

The compressor may not be working properly. This can be because of 4 main reasons. The capacitor, washer, piston, or the bearing of the compressor may have been damaged. If possible, you can replace these components separately. Else, you need to replace it with a new one.

Compressor, Oxygen Concentrator
The compressor of the Oxygen Concentrator
Washer of the Compressor, Oxygen Concentrator
Washer of the Compressor

The compressor operates at 240 VAC. Similarly, the capacitors might operate at 6 µF, 10 µF, 15 µF, etc. You can directly give an AC supply to the compressor and check it. In the case of the capacitor, I suggest you cross-check it with a new one. 

 

6. Solenoid Valve

Solenoid Valve, Oxygen Concentrator
Solenoid Valve

The solenoid valve operates on a set of zeolite towers. When a certain pressure in the oxygen tank is reached, the valve makes a click sound. After that, the path of the oxygen changes in another direction. After the click sound, the unfiltered gas (eg. nitrogen), returns from the zeolite tower to the valve. Then it goes to the environment.  You can hear a different sound when the unnecessary gases return to the environment.

If the valve does not make a click sound, then you can manually supply 12 VDC to the valve and check it. Similarly, if the output from the compressor does not meet the required air pressure, then the valve may not operate even after making a click sound. So, you may need to cross-check both the compressor and the solenoid valve.

Zeolite( Al2SiO5)

Zeolite, Zeolite Powder 13X
Image Source:- https://www.chemistryworld.com/podcasts/zeolites/4010734.article

Zeolite tower consists of zeolite. It is a naturally occurring, crystalline, microporous compound. Nowadays, these compounds are also synthesized to form a powder.

1. Working Mechanism

It is based on the process of adsorption. When gas or liquid passes through the zeolite surface, smaller-sized molecules pass through the surface while larger-sized molecules are adsorbed by the surface.

2. Zeolite for Adsorption 

Zeolite is the major source of filtration in the oxygen concentrator. The most widely used zeolite for the oxygen concentrator is zeolite 13X. You will find zeolite inside two of the zeolite towers. 

When compressed air is passed through zeolite powder, oxygen passes through it. Other gasses such as nitrogen and argon having higher molecular size get adsorbed by the power.

Life Span

Generally, the life span of zeolite powder is above 2 years (in the case of an oxygen concentrator).

 

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