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What is an Oxygen Concentrator and How Does It Work?

If you are new to oxygen therapy, there are likely tons of questions on your mind. It is a treatment prescribed by doctors to patients suffering from various forms of respiratory illnesses. There is about only 21% of oxygen in the ambient air, which may not be enough for people unable to absorb it effectively through their lungs. 

Oxygen concentrator removes nitrogen from ambient air using a simple method that requires no external O2 in the form of liquid and delivers pure oxygen to patients. In this guide, we will cover everything you'd want to know about these machines. Let’s dive in!

What is an Oxygen Concentrator?

It is an automated device that supplies oxygen to a person through a face mask or a nasal cannula. The stationary units run on electricity, and portable devices are battery-operated, often rechargeable. The main components of a typical O2 concentrator are an air compressor, filters, tubes, and mask or nasal cannula. 

Brief history

The element O2 was discovered by Carl Wilhelm Scheele, a Swedish chemist, in 1772. In 1885, a pneumonia patient was treated using oxygen therapy for the first time under Dr. George Holtzapple. These devices were huge and bulky back then. Now you can get one as small as a coffee mug. Oxygen therapy use in the medical industry rapidly grew during World War II.

Regular maintenance involves

It is recommended to place these devices somewhere with good ventilation. Keeping it and the surrounding air clean is mandatory for proper functioning. The sieve beds inside these concentrators that filter nitrogen can harden if they are not used for a long time. Whether you are on oxygen therapy or not, if you own a device, make sure to run it for at least 10 to 12 hours every month. 

Why is it important?

There are various gases in the air, of which the primary ones are nitrogen and oxygen. Others include carbon dioxide, hydrogen, and neon. Our body cells require oxygen for producing energy. Lack of oxygen can cause overall organ failure—people with blood oxygen levels of 60 mmHg or less need supplemental supply. 

Who needs oxygen therapy? 

An average person breathes about ten times per minute. When we breathe, the air goes into our lungs, where the oxygen is absorbed while the carbon dioxide is released as we exhale. Asthma, pneumonia, COPD, and emphysema are common illnesses that disrupt our bodies' oxygen supply. But a person can have difficulty breathing for a wide array of reasons. Even panic attacks and anxiety can hinder the process. When there is a shortage of O2, your body goes into a state of hypoxemia and fails to function properly. In such circumstances, a supplemental supply of oxygen becomes necessary. 

Are they for patients with severe illnesses only?

Not all patients are required to have life-threatening conditions to use O2 concentrators. For example, some suffer from sleep apnea, a sleeping disorder that causes abnormal breathing when you're asleep. It is a condition that affects 25% of men and 10% of women. Although its immediate side effects can be mild, like daytime fatigue, in the long term can lead to life-threatening illnesses, including type 2 diabetes and stroke. 

Oxygen therapy helps patients combat these breathing problems. Doctors check blood oxygen levels to determine if a person needs the treatment. The dosage needs to be prescribed by your doctor. Because too much oxygen can be dangerous (110+ mmHg) as well. 

How do these machines work? 

The machine has a very straightforward process: 

  • Suck in surrounding air

The air compressor in the device pulls in air and compresses it. So it is critical to ensure there is at least room of about six inches all around it for unrestricted airflow. 

  • Compress, purify, and filter it

The compressed air then passes through sieve beds that clean it of nitrogen and other contaminants. As soon as one sieve bed is packed with nitrogen, the machine switches to the other bed. This process is repeated over and over again to maintain a steady release of nitrogen and other gases from the device.

  • Deliver clean oxygen to the user

The remaining gas is pure oxygen (up to 95%) that travels through the hose into the patient's lungs. Face masks and nasal cannula are commonly used to breathe in the purified gas. 

The need for supplementary O2 differs from person to person. For example, sleep apnea patients often take it while they sleep. Some only need it after a heavy physical workout. Doctors test and prescribe patients the required frequency and duration of therapy. 

How are they different from liquid oxygen containers?

In contrast, O2 Cylinders have a limited volume of oxygen compressed into a cylindrical container. If a patient uses liquid oxygen cylinders, they will need to refill or replace them once they run out. Thus, to avoid the risk of running out of oxygen, patients would have to store extra cylinders in their homes. These are bulky and take up a lot of space. There is also a higher risk of fire due to leaks in these containers. 

Why are they a better alternative to other devices? 

Patients using concentrators feel much safer and at ease because of its efficient and risk-free process of delivering oxygen. From one end, the ambient air enters the device and passes through filters and the compressor to reach the switch valve, which divides the air supply between the two sieve beds. Once the filtration process is complete, pure oxygen is supplied to the patient through the flowmeter while the remaining gases are pushed out of the device through the release valves. 

Types of Concentrators Available

Continuous Flow (CF) and Pulse Dose (PD) are the two main types of Oxygen Concentrators (OC). 

Continuous flow (CF)

CF provides the user with an uninterrupted oxygen supply. The amount of O2 needed per minute can be set in liters. The machine requires sufficient power to supply oxygen continuously in large quantities. That's why mostly this type of OCs are stationary. They are made to be used at homes. You can use regular wall sockets to power them. 

Pulse dose (PD)

In contrast, the PD type is a portable device. It is battery operated thus can't supply O2 continuously. Some models are as small as a can of soda. They work in conjunction with the breaths you take. Meaning, when you breathe in, they supply oxygen then stops while you exhale. This process also reduces wastage. Since doctors prescribe the amount of supplementary O2 needed, you can set the supply per minute on PD devices and use various settings. 

Which ones are quieter?

All concentrators make some noise. But since the technology has advanced, these devices are significantly quieter now than they used to be. We use decibels to measure their noise levels which can range anywhere from thirty-one to sixty decibels. 

Advantages of Using Stationary Machines

  • Unlimited oxygen supply 

As the device powers from a wall socket, there is no limit to how long you can use it. Patients who need continuous O2 supply can rely on these devices more confidently. 

  • Safer 

Stationary units are typically installed in a specific space, and as you don't move around with them as much, there are fewer chances of leakages. Also, you are unlikely to be close to a flame or heat source when the unit is set in a safe place. 

  • Low maintenance cost

Despite the upfront cost, in the long term, you save more money with these devices. They run on electricity, so you do not have to replace batteries. Also, as they stay in a place, there is lesser wear and accidental damages to the device. 


  • Can be noisy

As these units are slightly bigger and provide continuous oxygen supply, the air compressor in these devices tends to be bigger and can produce more noise than its portable counterparts.  

  • Can be a problem if there is a power outage 

Running on electricity sounds more reliable, but a power outage can be a problem. Thus you should make additional backup arrangements if the patient dependency on these devices is high. 

Advantages of portable machines 

  • Easy to carry around

To most people, the freedom to move around and be anywhere they want means a lot. The mobile O2 concentrators allow people with respiratory illnesses to carry on with their routines without sitting down for therapy. 

They are easy to move around the home. You can also wear these lightweight devices and take them with you when you go out for a walk or shop. Portable ones for home use often come with wheels and weigh about twenty pounds. The wearable ones can weigh less than five pounds and can be easily carried in a backpack. 

  • Lesser oxygen wastage

These units use the pulse dose technology, which means it only pumps oxygen into the nasal cannula when you breathe in. Thus no O2 is wasted while you exhale. Continuous flow devices provide a non-stop oxygen supply and don't stop pumping oxygen even while exhaling. 

  • Ideal for traveling 

Taking a flight with an O2 concentrator used to be a hassle for patients. These mobile units enable them to travel with ease. Like their other portable devices, they could carry around the travel concentrators anywhere they go. 

  • Easy to use in public 

These devices are well-designed and modern-looking, which means using them in public places is more manageable than traditional ones. They can be carried around in travel cases and are very comfortable and discreet to use. 


  • Lower flow rates

Since they are battery-operated, these units cannot match the oxygen supply of stationary ones running on electricity. Patients who require a continuous flow of O2 find immobile devices more suitable for everyday therapy. 

  • Batteries need to be recharged or replaced

Like with all mobile devices, with portable concentrators, there is an additional cost of spare batteries. On the other hand, using rechargeable batteries solves the problem, but the device will be unavailable for use while it is on charge. 

Challenges of using these devices

Whether you use a portable device or a stationary one, oxygen is highly flammable, and some precautions need to be taken. 

  • Burning cigarettes or other flame sources, like stoves, must be kept away from the device. 
  • Installing additional fire alarms around the house is also recommended. 
  • Oxygen overdose can lead to problems, such as muscle twitching, dizziness, and nausea. It can also cause free radicals overproduction in the lungs that can destroy tissues inside. 
  • It can take some time to get used to sleeping with a mask or nasal cannula strapped to your face.
  • Lack of understanding of oxygen and not treating it like a drug increases the likelihood of misuse. 

Benefits of using these devices 

  • Makes you feel better.

When people are feeling oxygen-deprived, they tend to experience symptoms like dizziness or lightheadedness. Breathing O2 at normal pressure can help to alleviate the symptoms of oxygen deprivation. Up to 15 hrs of therapy per day can improve how you feel and go about your daily chores with more energy. 

  • Helps you sleep better

Patients with respiratory illnesses cannot get a good night's sleep because of their condition. Getting O2 therapy during sleep means providing your body with a continuous oxygen supply throughout the night. You're able to rest appropriately and don't feel tired the next day. 

  • Stay in a good mood

When your body is unable to get proper sleep at night, it struggles to function correctly. The common side effects are drowsiness, feeling agitated, annoyed, and frustrated. Oxygen therapy helps patients with sleep disorders fully relax and recover during sleep, enabling them to feel more active and alert. Thus they stay in a happy mood all day long. 

  • More energy 

If you ever wonder why after doing everything right, you still feel tired all the time, chances are your body isn't getting the oxygen supply it needs to keep you fresh and active. People who use these machines to overcome O2 shortages in their blood experience a drastic improvement in their energy levels. They can focus better, stay alert, and as the dullness disappears, they feel motivated and active throughout the day. 

Do you have to own one or can you rent it? 

These concentrators are not the most affordable devices and can cost up to twenty-five hundred USD. Some people in need of oxygen therapy might wonder if they can rent one instead. 

Why should you own a new one?

It is true, owning the device means a high upfront cost, but there are benefits too. Making monthly payments can be stressful. Also, if you're going to be needing the device for the long-term, renting might turn out to be even more expensive. 

The good news is that most vendors offer an installment option. You don't have to pay a hefty check upfront. Plus, the money you pay in installments isn't just for using the device. You'll own the equipment once all payments have been made. 

Brand new devices are also safer than used ones. There are fewer chances of leaks and malfunctioning. They come with a warranty too. And often, you get accessories for free, which is an added value. 

How to rent one?

O2 concentrators can be rented as durable medical equipment (DME) under Medicare Part B if you want to rent one. You can consult with your doctor about renting options. 

Typically, the initial three years' rental cost would be about twenty percent of the total cost. After three years, the equipment supplier should continue to provide service and maintenance for the next five years at no additional charge. If you need oxygen therapy for longer, after completing these five years, you will have the option to stick with your current supplier or switch to another for the new thirty six-month rent cycle. 

Getting a second-hand concentrator 

Do not get a used device from an unreliable source. Before you agree to take the device, you want to ensure the machine works correctly. O2 devices need to deliver the right amount of oxygen to patients as prescribed by their doctors. That's why just because it turns on and appears to run doesn't signify it is delivering oxygen at purity levels you need. 

If you're planning on getting a used one, look for an established company with a good reputation and certified technicians on board. Doing so will allow you to ensure the used device is carefully tested and repaired and won't cause any unnecessary problems. Ideally, choose one that comes with a warranty. 

How to choose the right one? 

  • Portability

The portability factor is essential if you're using the machine to travel or use it in the office. If you're going to be lugging the device around with you all day, you want to make sure that it's not too heavy or bulky.

  • Durability

You do not want it to break down on you when you need it the most. The device's quality can determine durability, so you want to make sure you find a concentrator of high quality.

  • Type

Typically, these devices come in two different oxygen delivery modes: pulse dose and continuous flow. Pulse dose concentrators are recommended for patients who need supplemental oxygen for short periods. Continuous flow concentrators are for those who need oxygen therapy at home while sitting or sleeping.  

  • Flow rate

A concentrator's flow rate measures how many liters of oxygen it can deliver per minute. It's essential to consider the flow rate to ensure the patient receives the right amount as prescribed by the doctor. 

  • Power consumption 

These devices come in many different sizes and shapes, and they all have varying power consumption levels. While some are more powerful than others, it's important to remember that power consumption impacts your oxygen supply. Also, the more power it consumes, the higher the cost of operation will be.

  • Weight

As a general rule, the lighter the concentrator, the easier it will be to transport. If it features a carrying handle or some other type of grip, it can be easily lifted and moved from one place to another. 

  • Noise

The two main factors that affect a concentrator's noise levels are the fan's size and the compressor. A larger fan and compressor will usually mean a louder device. There are quieter machines available, but they can be more expensive than the loud ones. It's also important to consider the location where you'll be using it. 

Are these devices long-lasting?

Various factors affect the lifespan of O2 concentrators. The hours of usage is an obvious one. But other than that, it would help if you were careful of the room temperature where the device is kept. Additional elements, such as humidity and cleanliness, also play a role in extending or decreasing its lifespan. 

Traveling with an O2 concentrator 

You can only travel with portable concentrators, no tanks or liquid oxygen. All flights in the United States are required by law to allow mobile O2 devices if the patient needs them. Ideally, it would be best to get a written prescription from your doctor before catching your flight. If that's not an option, then talk to the airline before making a booking. Talking to them will also help you become aware of any instructions that need to be followed. 

One of the common questions people ask is how to charge their portable O2 devices on the flight. Carrying extra batteries is essential; you cannot rely on the airline to provide you with a power socket. Also, spare batteries need to be kept in original packaging or separate plastic bags with their terminals insulated. 

Can you use one during pregnancy? 

Yes, you can use a concentrator during pregnancy. However, it's recommended that you consult with your doctor before using one. Every case is different, and you do not want to rely on general advice in such sensitive matters. Your doctor should be able to conduct the tests required to ensure whether you should or shouldn't use O2 concentrators. Also, they need to prescribe the right amount of dosage for you. 

Is oxygen therapy addictive? 

Oxygen therapy is not addictive in the same way that alcohol or cigarettes are. It is not considered a substance, so you cannot abuse it. Additionally, oxygen is an odorless, colorless gas that doesn't trigger a response in the brain the same way that other substances can. 

It has been used for decades in hospitals and clinics, and the beauty of it is that it's an all-natural treatment. Oxygen is derived from the air we breathe, so you're not inhaling anything harmful, or that's going to cause any damage as long as you stick to your doctor's prescription and do not misuse it in any way. 

How to measure your oxygen levels at home?

Measuring your oxygen levels at home with a pulse oximeter is easier than you think. These devices have grown in popularity in recent years because they're portable, cheap, and accurate. It is a small device that clips onto your fingers or earlobes and automatically detects your O2 levels. 

You can use this device on your own to measure your blood O2 levels. For your convenience, the results are displayed on the device in numbers. These numbers are percentages. The standard blood oxygen level is anywhere from ninety to a hundred percent. 

For accurate results, use the device according to its manufacturer's instructions. Also, consult with your doctor about when to check your O2 levels. When you use it on your finger, ensure your hand is warm and relaxed and not lifted above your heart level. Also, stay still while measuring. External elements, like nail polish, can interfere with the calculations, so make sure you remove them before using the device. 


The right oxygen concentrator will help you overcome breathing difficulties with ease. Not only will you be able to breathe normally, but you're going to see a dramatic improvement in your overall health and energy levels. 

When choosing one, there are various features to look out for, such as accuracy in oxygen sensing, flow rate, ease of use, affordability, low maintenance, etc. Keeping your needs in mind will help you determine which features are most important to you. If you're not sure where to start, check out some of the top-rated oxygen concentrators here.