Oxygen Therapy Delivery Systems

Many respiratory diseases require special equipment for treatment and therapy. With everything from asthma inhalers to oxygen concentrators, the list of equipment can be intimidating. We'll help you navigate through it.

Overview of Oxygen Equipment/Delivery Systems

The human body needs oxygen to survive; this is certainly no secret. Unfortunately, some people’s bodies lack the ability to take in the oxygen they require. This issue can be seriously debilitating, if not life-threatening. Thankfully, advances in medical technology have provided people a number of oxygen therapy systems to meet a variety of needs. The three main types of supplemental oxygen therapy delivery systems include: Compressed Oxygen Cylinders, Oxygen Concentrators (Portable and Stationary), and Liquid Oxygen. Choosing an oxygen therapy system may seem overwhelming at first, but picking the right one can make life exponentially easier.

Feature Comparison of Supplemental Oxygen Therapy Delivery Systems
Compressed Oxygen Compressed Oxygen Cylinders Delivery Systems
Stationary Concentrators Stationary Concentrators Oxygen Delivery Systems
Portable Concentrators Portable Concentrators Oxygen Delivery Systems
Liquid Oxygen Liquid Oxygen Oxygen Delivery Systems

None Required
Standard Home Outlet
Rechargeable Battery
Standard Home outlet for Reservoir

Refill Process:
Home Delivery Available
None Required
None Required
Transfer from Home Reservoir

Air Delivery:
100% Oxygen
95% Oxygen, 5% Ambient
95% Oxygen, 5% Ambient
100% Oxygen

Bulky and Heavy
"Dorm Fridge" Size
Handbag to Rolling Suitcase Size
Handbag to Backpack Size

Check Valves Periodically
Replace Filter Periodically
Replace Filter Periodically
Check Valves Periodically

Flow Rate Adjustment:
Analog via Valve Gauge
Digital Setting
Digital Setting
Analog via Valve Gauge

Oxygen Capacity:
Dependent on Tank Size
0.7 - 1.0 Liters for Portable Tank

Safety Considerations:
Damage to Valve or Tank Can Cause Explosion
Ports can cause Frost Burn if not Handled Correctly

Smaller Capacity Tanks Available
On wheels for Moving from Room to Room
Shoulder Strap or Cart
Mobile Tanks: Yes, Reservoir: No

FAA Approved:
Most meet FAA requirements

Intermittent Flow:

Continuous Flow:


Overview of Compressed Oxygen Cylinders Delivery Systems Compressed oxygen cylinders are perhaps the most well-known, and possibly the most iconic type of oxygen delivery system. They are the most basic and simple form of oxygen therapy, and also one of the most reliable. The cylinders consist of a tank filled with compressed oxygen, a valve that is manipulated to deliver a specific amount of oxygen and a plastic delivery tube. Tanks for home use are generally very large and bulky, rendering their mobility challenging. The tanks are supplied and home-delivered by a medical supply company. The tanks then need to be secured in a sturdy manner, in order to ensure the tanks’ safety. Smaller portable tanks are available for mobile use.

Compressed oxygen is placed inside of steel tanks which are built to withstand the internal pressure of the compressed gas. A flow regulator allows oxygen to be delivered to a person, at a lower pressure, while still maintaining the pressure inside the tank. Oxygen is a volatile gas and under pressure, it can become dangerous. The tanks are constructed to keep the oxygen from combusting, but additional care should be taken to secure the tanks in an upright position, at relatively low temperatures, and away from any potential falling objects.

While the bulky size of the larger tanks renders them impractical for portable use, it makes them highly effective for home-use. A key is used to open and close the tank’s valve. The tanks carry enough oxygen to last a considerable amount of time, depending on the relative flow rate being utilized. Once the tank approaches empty they must be replaced immediately, as to prevent a life-threatening situation for someone that is oxygen dependent. It is wise to keep a small replacement cylinder on hand just in case the large oxygen cylinder runs low without being noticed. Because these tanks operate on their own, they do not need an outside source of power, such as a home’s electrical outlet or a battery.


Oxygen concentrators take in the ambient air from the environment, isolate the oxygen, and deliver a concentrated dose of oxygen. They consist of an air compressor and zeolite-filled container. The compressor brings the ambient air into the machine. Ambient air is made up of roughly 78% nitrogen and 21% oxygen. The zeolite minerals absorb the nitrogen to separate it from the oxygen, resulting in a concentrated dose of up to 95% pure oxygen. Oxygen concentrators come in many different sizes, and can fit almost any need, whether that need is at home or on-the-go. Home oxygen concentrators (HOCs) tend to be larger than their more portable counterparts, but they are more efficient in both their oxygen delivery and their energy use. They plug right into a household electrical outlet, and often times come with a set of wheels, allowing them to be transported from one room to another, if needed.

Overview of Oxygen Concentrators Delivery Systems HOCs output a continuous flow of oxygen. A continuous flow of oxygen provides consistent, high levels of oxygen to keep the body as healthy as possible. HOCs feature oxygen outputs ranging anywhere from 2 Liters per Minute (LPM) up to 10 LPM.

Portable oxygen concentrators (POCs) differ from their home counterparts in a number of ways. First, they are smaller and lighter. This, of course, allows them to be easily transported anywhere their user needs to go. Since a wall outlet is impractical for a portable device, POCs run on a battery. Battery life varies from model to model, so it is important to know how long the battery will last, and plan trips accordingly. The last thing anyone wants is to run out of oxygen away from home.

Another major difference between portable and home oxygen concentrators is the way the oxygen is delivered. Instead of being a continuous flow, portable concentrators deliver a pulsing, otherwise referred to as intermittent, flow of oxygen. This results in lower doses of oxygen, but allows for a longer battery life, as well as a smaller, lighter design.


In extremely cold temperatures (-300°F) oxygen changes from a gas state to a liquid state. In a liquid state, the same amount of oxygen takes up about one tenth of the volume of oxygen than does a gaseous state. Because of the lower volume, large amounts of liquid oxygen can be stored using much less pressure than compressed oxygen in the gaseous phase. Liquid oxygen can be stored and used for oxygen therapy. Overview of Liquid Oxygen Delivery Systems

The liquid oxygen is kept in a large reservoir tank. An empty portable unit can be filled from the reservoir tank and used for therapy. In some cases, supply tubes can be connected directly into the reservoir, so that the reservoir tank itself can be applied for home use.

Liquid oxygen is kept under far less pressure than compressed oxygen, making it safer and less volatile. The down-side is that the ports are exceptionally cold, and can burn the skin quite badly if touched. Much care is needed when filling a portable unit directly from a liquid oxygen source. When the unit is turned on, the liquid warms, changing phases from liquid to gas, and is safely supplied to it’s user at room temperature.

Liquid oxygen units come in sizes ranging from 0.7 liters to more than a full liter, and only weigh between 6 and 9 pounds. The oxygen is delivered at a continuous flow, and depending on the unit, oxygen output is at either 0-6 liters per minute (LPM), or a high flow output of 15 LPM. Because of their small size and relative light weight, the portable units can be transported easily with a shoulder strap or a cart. The oxygen will remain in liquid form in the reservoir tank, but once the portable tank is filled, it will begin to empty. With these systems, it is important to only fill the portable tanks immediately before use, to avoid unnecessarily wasting the oxygen.

Choosing the Appropriate Oxygen Therapy System:

With dozens of models to choose from, picking an appropriate product seems like a daunting task. To make the decision easier, it is important to narrow the search by determining which features are most important to the user’s needs. Everyone’s needs are different. There is no single, ‘best’ model. There is a ‘right’ model, but it varies from one person to the next.

The most important factor is an understanding of the daily oxygen requirement of the user. If large amounts of oxygen are needed, a high-output machine is necessary. If there is any question about how much oxygen is needed, or if a certain model will provide the proper dosage, consult a doctor before purchasing.

Another important factor is where the oxygen will be used. If used in the home, it is important to make sure a clear space is available in the room that the oxygen will most frequently be used. If using an HOC, make sure that an outlet is available where the HOC will be placed. If a portable oxygen system is desired, it is important to consider how long the oxygen will be needed. Portable systems can only supply oxygen for a limited time. Be sure to find an oxygen therapy system that will not run out before the trip is over.

It’s important to make sure that the system is mobile, in the event this option is required. Portable systems need to be carried and moved for longer periods of time, but home systems should be easy enough to move from one room to the next when necessary.

It’s also important that the user knows how their oxygen therapy functions. Some devices have several settings, which can sometimes be misleading. Not knowing what each setting means can result in an incorrect dose of oxygen being delivered. This can be both dangerous and wasteful, so be sure you receive proper training on how to use the system, before operating it alone.

Delivery Systems Conclusion: Once a person’s specific needs are analyzed, the search can be narrowed to a select few products, leaving them with a much easier decision. Choosing the oxygen therapy system that fits best will assure that they are satisfied with their purchase. Purchasing the correct system, for one’s personal oxygen needs, will allow the user a higher quality of life while also enabling them to stay within their financial means.

How Oxygen Concentrators Work:

Oxygen Concentrators are medical devices that deliver medical grade oxygen (greater than 88% pure oxygen) to a patient via either a nasal cannula or mask. Air generally contains mostly nitrogen and only about 21% oxygen. Concentrators remove the nitrogen and "concentrate" the oxygen. Oxygen concentrator output is generally measured in LPM (liters per minute). A patient on oxygen therapy receives air with a higher concentration of oxygen than the ambient air. As opposed to a compressed oxygen tank, which delivers some amount of pure oxygen, a concentrator removes other components from the air, achieving the same effect more safely and at a lower cost. It’s a pretty straightforward idea, but how is it accomplished?

Animation of How Air is Converted in Pure Oxygen

Technical Explanation: A concentrator has two cylinders filled with zeolite which selectively adsorbs the nitrogen in the air. In each cycle, air flows through one cylinder at a pressure where the nitrogen molecules are captured by the zeolite, while the other cylinder is vented off to ambient atmospheric pressure allowing the captured nitrogen to dissipate. Typical units have cycles of around 20 seconds, and allow for a continuous supply of oxygen at a flow rate of up to approximately 10 liters per minute (LPM) at concentrations anywhere from 25% to 95%. This process is called the pressure swing adsorption(PSA) cycle.

Delivery Systems Specifications:

Key specifications for an oxygen concentrator are as follows:
  • Electrical / Power Requirements: Standard home concentrators run only on AC power. A "portable oxygen concentrator" by definition will run on AC power, DC power and batteries. Most home concentrators in the United States will only run on 110 Volts AC (often listed in specifications as 120 V AC +/- 10%)
  • Weight: The weight of home concentrators will vary from the lightest on the market today is 31 pounds to older units that can weigh more the 50 pounds.
  • Dimensions: Dimensions will vary with both manufacturers style and the age of the unit but all units are basically a "cube" shape of approximately 12 - 15" wide by 9" - 15" deep by 23" -28" tall.
  • Noise Level: Noise level on units is measured in decibels. The newer "quiet" units are approximately 45 decibels, older units typically do not have the same sound baffling and are slightly louder( 50 - 60 decibels). Additionally, as units age, the compressors can become louder. As a comparison, a "library whisper" is considered to be approximately 30 decibels and "normal conversation" is considered to be in the 60-70 decibel range.
  • Temperature Operating Range: Home oxygen concentrators are specified to operate in a normal home environment typically between 45 degrees F and 90 degrees F. Outside of these ranges, the unit may not function properly.
  • Altitude Operating Range: Altitude specifications for home concentrators vary slightly. Most are specified to operate up to 7500 - 8000 feet. This specification limitation is because the oxygen percentage in the air at higher altitudes decreases.
  • Oxygen Concentration: Any oxygen concentrator should deliver "medical grade" oxygen. Medical grade is typically defined as 88% pure oxygen and above. Most new concentrators are specified to have between 92 - 95% pure oxygen (+/- 3%)
  • Warranty: Warranties vary with manufacturer. Most manufacturers have a 3 or 5 year warranty. Patients should clarify both the length of any warranty and the start date of the warranty as some manufacturers start the warranty when the unit is shipped to the retailer.

Oxygen Glossary:

Air Purifying Respirator
Blood Gas Analyzer
A machine that measures oxygen, carbon dioxide, and pH levels in a blood sample. These extremely important measurements are required to care for patients in the hospital, especially sicker patients with lung & heart disorders.
Body Plethysmograph
A machine used in lung (pulmonary) function labs to measure lung function in order to diagnose and quantify lung disorders.
A fiber-optic scope that is inserted into the patient's airways (bronchi) to visualize and obtain samples for diagnosing lung disorders and sometimes used for removing obstructions in the airways. This is one of the more common tools used by specialists in helping diagnose lung diseases.
Clean Air Box compressed air systems for Grade D air.
Cardio Respiratory Monitor
A monitor that measures and continuously displays heart rate & rhythm, blood pressure, and respiratory rate. These are important "vital signs" that are monitored in acutely ill patients.
Emergency Escape Breathing Apparatus
Same as a bronchoscope but is used to assess the esophagus rather than the bronchi.
Immediately Dangerous to Life and Health
A device that is used in the procedure of placing an artificial airway (endotracheal tube) into a patient's trachea in order to maintain their airway open. Used for unconscious patients, patients that can no longer breathe on their own, etc.
A device that either adds humidity to dry medical gas that a patient is breathing or provides a mist of medication that a patient can breathe in.
Oxygen Analyzer
A device that measures the oxygen levels (concentration) in a breathing system. Delivered oxygen levels need to be increased in order to provide enough oxygen to patients with lung or heart disorders.
Oxygen Concentrator
A machine that takes in atmospheric air (with 21% oxygen) and concentrates the outgoing gas to 100% oxygen. Used to provide patients with supplemental oxygen (higher oxygen levels than room air).
Oxygen Monitor
A machine that provides continuous oxygen monitoring for hospital and home ventilators, and NICU and aesthesia delivery equipment.
Powered Air Purifying Respirators that use a blower that draws air through cartridges or filters.
Pressure Demand Airline Respirator
Peak Flow Meter
A device that helps patients monitor their asthma easily.
Pulmonary Function System
A system that tests people's breathing in order to diagnose lung disorders.
Pulse Oximeter
A device that measures oxygen saturation and assesses pulse rate.
See ventilator.
Supplied Air Respirator
Self Contained Breathing Apparatus
A device that tests lung function; is one component of a complete pulmonary function machine.
Suction Regulator
A device that controls the amount of suction (vacuum) that helps in removing secretions from a patient's airways, lungs, thoracic cavity, stomach, or other body cavities
A machine that assists or provides all of the breathing for patients who cannot breathe on their own (also known as a respirator).

Additional Equipment Info:

Page last updated: October 10, 2018