The device most people call an “oxygen machine” is formally known as an oxygen concentrator. It’s the most common type of home oxygen equipment, and it works by pulling in room air, stripping out the nitrogen, and delivering purified oxygen at concentrations between 85% and 95%. You may also hear the broader term “oxygen delivery device,” which covers concentrators along with two other systems: compressed oxygen tanks and liquid oxygen units.
How an Oxygen Concentrator Works
Room air is about 78% nitrogen and 21% oxygen. An oxygen concentrator uses a filtration system with components called zeolite sieve beds to separate and remove the nitrogen. What comes out the other end is medical-grade oxygen delivered to you through a nasal cannula (a lightweight nose tube) or a face mask.
Home oxygen concentrators plug into a standard wall outlet and run continuously at a steady flow rate. They’re designed for stationary use, sitting in one spot in your home while you go about your day connected by tubing that can stretch across a room. Common models produce between 3 and 10 liters per minute of continuous oxygen, with most home users needing less than 5 liters per minute.
Portable Oxygen Concentrators
Portable oxygen concentrators (often called POCs) work on the same principle as home units but run on rechargeable batteries. The key difference is how they deliver oxygen. Most portable units use pulse dose delivery instead of continuous flow. Rather than pushing out a steady stream of oxygen, a pulse dose unit has a sensor that detects each time you inhale and releases a small burst of oxygen at that exact moment. This is far more efficient because a continuous flow device wastes oxygen every time you exhale or pause between breaths.
POCs are small enough to carry in a bag or roll on a cart, making them practical for errands, travel, and daily life outside the house. They can also be plugged into a wall outlet when you’re home.
Compressed Oxygen Tanks
The classic green metal cylinder is a compressed oxygen tank. These store pressurized oxygen gas and come in various sizes, from large stationary tanks to smaller portable ones you can carry or wheel around. A gauge on the tank lets you adjust the flow rate. Some portable tanks can be refilled at home, while others need to be returned to an oxygen supply company for a swap. The tradeoff is straightforward: smaller tanks are easier to carry but hold less oxygen and run out faster.
Liquid Oxygen Systems
Liquid oxygen systems store oxygen that has been cooled to negative 297°F, compressing it into liquid form. These setups typically include a large stationary storage unit at home and a smaller portable container you can fill from it. They deliver high-concentration oxygen without electricity, which makes them useful during power outages. The liquid is extremely cold, though, and can cause frostbite burns on contact with skin, so filling the portable tank requires care.
Concentrators vs. CPAP Machines
People sometimes confuse oxygen concentrators with CPAP machines, but they do completely different things. A CPAP machine treats sleep apnea by pushing pressurized room air through a mask to keep your airway open while you sleep. It doesn’t add extra oxygen or filter out nitrogen. It simply takes regular air and delivers it at enough pressure to prevent your throat from collapsing. An oxygen concentrator, by contrast, enriches the air you breathe by increasing its oxygen content. One treats a structural airway problem, the other treats low blood oxygen levels caused by conditions like COPD or other lung diseases.
Who Qualifies for Home Oxygen
Oxygen concentrators require a prescription. Medicare and most insurers cover home oxygen when your blood oxygen saturation is at or below 88% at rest while breathing room air. Coverage can also apply at 89% saturation if you have certain complications like pulmonary hypertension or significant swelling in the legs from heart strain. Your doctor will typically measure your oxygen levels with a pulse oximeter or an arterial blood gas test to determine whether you meet the threshold.
Traveling by Air With a POC
Compressed oxygen tanks and liquid oxygen systems are not allowed on commercial flights, but FAA regulations permit portable oxygen concentrators on board as long as the device meets specific criteria. The POC must be FDA-cleared for sale in the United States, must not interfere with aircraft radio systems, and must not generate compressed gas or contain hazardous materials beyond its batteries. Approved devices carry a red label from the manufacturer confirming they meet FAA acceptance criteria. If your POC has that label, you can use it during the flight. Airlines may ask to see it before boarding, so keep it visible on the device.
Basic Maintenance
Oxygen concentrators need regular upkeep to stay effective. The outer particle filter, usually a piece of foam that catches dust and pet hair, should be cleaned weekly with warm soapy water and air-dried before putting it back. Internal HEPA filters typically need replacement every one to two years, depending on air quality and how often you run the machine. The zeolite sieve beds, the core components that actually separate oxygen from nitrogen, are serviced by a technician and generally last two to three years before needing replacement.
One easily overlooked tip: run the concentrator for at least 10 hours per month even if you’re not using it regularly. This keeps internal lubricants moving and prevents the sieve beds from hardening, which can shorten the life of the machine. When the unit’s alarm goes off indicating low oxygen purity, that’s usually a sign the sieve beds need professional service.