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Review Pulse Flow Portable Oxygen Concentrators with Comparison Chart

FreeStyle Portable Oxygen Concentrator with people

Review Portable Oxygen Concentrators with Comparison Chart

Portable Oxygen Concentrators offer oxygen therapy for patients who live active lifestyles. AirSep Focus Portable Oxygen Concentrator - The Smallest Oxygen ConcentratorPortable oxygen concentrators come in two basic types--pulse flow and a combination of pulse flow and continuous flow oxygen. A pulse flow concentrator provides puffs of oxygen when the patient inhales. A continuous flow concentrator provides oxygen flow regardless of whether the oxygen patient is inhaling or exhaling. Many oxygen patients find that pulse flow is more comfortable because they do not have to fight against incoming oxygen when they are exhaling. Patients that need continuous flow oxygen often like the ability to switch between the two oxygen flows, using continuous flow when they feel they are not getting enough oxygen and using pulse flow at all other times. The portable oxygen concentrators that provide continuous flow as well as pulse flow can be viewed at this link - Continuous Flow Portable Oxygen Concentrators along with comparison charts and reviews at Review Portable Oxygen Concentrators with Continuous Flow.

For the purposes of this concentrator review, we will examine only the top pulse flow portable oxygen concentrators. Sometimes these oxygen concentrators are referred to as "Carry-Concentrators" because of their small size and low weight. The combination of small size and low weight make these oxygen concentrators easy to carry in a small shoulder bag or backpack wherever the oxygen patient wants to go. Many oxygen patients find that they like the independence and freedom that these smaller oxygen concentrators offer.

Since Pulse Flow Portable Oxygen Concentrators are smaller machines, they generate smaller amounts of oxygen and are therefore not a good choice for oxygen patients who require larger doses of oxygen. Generally, the pulse dose oxygen machines work well for oxygen patients who require 2 or less liters of oxygen per minute (LPM). Since most oxygen patients in the USA require only 2 LPM or less, a portable oxygen concentrator is a good purchase decision for many.

This portable oxygen concentrator review examines the top ten pulse flow oxygen concentrators on the market that offer at least 2 liters of oxygen therapy per minute or equivalent. These concentrators include the Focus, FreeStyle 3 and FreeStyle 5 from AirSep; the G2 and the G3 from Inogen, the Activox PRO and the Activox 4L from Inova Labs, the Oxus, the XPO2 from Invacare, and the EasyPulse POC-5 from Precision Medical. A side-by-side comparison of the Top Ten Portable Oxygen Concentrators - Pulse Flow is provided below this review.

Additional oxygen concentrator reviews, rankings and comparison charts can be viewed by clicking on the links below:

Ranking the Top Ten Portable Concentrators by Size and Weight

Size and weight are two of the most important factors to consider in selecting a portable oxygen concentrator, particularly if you are carrying your oxygen concentrator with you. Just a few pounds can easily become a heavy burden. A few inches bigger means bumping into more walls, doorways and furniture. Small lightweight oxygen concentrators are essential for day-to-day use away from home.

The most technically advanced small, lightweight oxygen concentrators are manufactured by Chart Industries under the "AirSep" brand name. The smallest size and lowest weight concentrator is the AirSep Focus. Weighing less than 2 pounds and occupying only 76.80 cubic inches, the Focus nearest competitor is more than twice its size and weight and is also made by AirSep, called the FreeStyle 3. Contrasting the number 1 and number two lightweight concentrators, the Focus weighs more than 2-1/2 times less than the FreeStyle 3 and is almost 2-1/2 times less in size. Essentially, the Focus Portable Oxygen Concentrator has no competition for a lightweight, small size concentrator. Ranked third for size and weight is the Inogen G3 at 4.8 pounds and 190.31 cubic inches. The beast of the small "carry-type" portable concentrators is the Oxus, weighing nearly 10 pounds and with a size of 506.46 cubic inches--more than six times the size of the Focus. The chart below rank orders the top ten portable oxygen concentrators by weight and size.



As shown in the chart above, the AirSep Focus is positioned on the far left-bottom with the smallest bubble size, representing that it is the smallest size portable concentrator while the Oxus has the largest bubble, representing the largest size concentrator. The larger the bubble size and the higher the bubble placement on the graph, the bigger its size. The weight of the concentrators is also compared on this chart with the Focus at the left of the chart between 1 and 2 pounds while the Oxus is at the far right hovering at the 10 pound marker. The farther the bubble appears on the right of the graph, the heavier the concentrator. The average size for the top ten portable concentrators is 285 cubic inches indicated by the horizontal red line across the graph. The Focus, FreeStyle 3 and the Inogen G3 all have smaller sizes below the average. The average weight for the top ten concentrators is 5.65 pounds as indicated by the red vertical line on the graph. Five of the concentrators, the Focus, FreeStyle 3, Inogen G3, Activox Pro and Activox 4L, have less weight than the average, and therefore are displayed on the left of the vertical average line. For oxygen patients requiring a lightweight concentrator as their top concern, the AirSep Focus is likely to be their best choice.

Top Ranked Portable Concentrators by Longest Battery Time

The top ten pulse flow portable concentrators are designed for travel to foreign countries. All of them have adaptable power requirements ranging between 100 to 240 VAC that allow you to operate the concentrator almost anywhere as well as recharge the battery. Each of these concentrators can also be powered by direct current from an automobile or recreation vehicle. Thirdly, these portable concentrators can also be powered under their own internal battery power.

This concentrator review will examine two important factors that bear on how long these portable oxygen concentrators can sustain operation under their own internal power source. These two factors are 1) the power consumption of the oxygen generator and 2) the battery duration between charging. It is important to note that each of these concentrators use a proprietary battery to operate while away from an external power source. These batteries are lithium ion batteries. Each of these concentrators come with rechargeable lithium batteries that you will not be able to replace or supplement by going to a local retailer like Target or Walmart. However, each of the manufacturers offer additional batteries for purchase as a replacement or to supplement you initial concentrator purchase.

The Oxus uses the least amount of power to operate at only 100 watts. The Inogen G2 and G3 follow closely behind, each using 110 watts. Four more concentrators also use less power than the average of 143 watts--the XPO2, Activox Pro, Activox 4L and EasyPulse POC-5. Three concentrators consume power well above the average. All three of these are manufactured by AirSep. The chart below displays a comparison of the pulse flow concentrators by rank for power consumption. It may seem odd that the concentrators with the least weight and size require the most power to operate, however, these models are designed to require less maintenance and more durability. The "power-hog" concentrator using the most power to operate is the AirSep FreeStyle 5 with a 240 watt power requirement.


Power consumption at home is usually not a significant factor for portable oxygen concentrators since they employ very small motors to facilitate easier travel. However, since portable oxygen concentrators most often are operating off of their internal battery power, low power consumption will generally allow the battery to power the concentrator for a longer period of time. Longer operating times while in portable mode is very important to oxygen therapy patients. Lower power requirements can translate into longer battery time before having to recharge, providing, longer excursions away from external power sources. No one wants to be tethered to an external power source for very long or very often.

The duration time of the internal battery is another very important consideration that bears on the length of time your concentrator will operate while away from an external power source. Even though each of these concentrators come from the manufacturer with at least one lithium ion battery, these batteries are significantly different from each other in size, weight, battery duration time and time required for recharging. Finding a portable concentrator with a small battery that is lightweight and that is able to power your concentrator for an extended time while only requiring a short time to recharge is ideal.

The chart below displays the rank order for concentrator battery time while using the concentrator on setting 2. The concentrators with the best battery times are on the left, while the concentrators with less battery time are on the right. The concentrator with the best battery duration time is the Inogen G3 achieving a 9.5 hour battery time with a 16 cell battery. Inogen also provides the G3 with and optional lightweight battery that weighs 1.1 pounds less than the 16 cell battery to power the concentrator motor for 4 hours. The two portable Activox concentrators rank second and third for battery duration with 8.25 hours for the Activox 4L model and 7.25 hours for the Activox Pro. Both Activox models offer battery times above the average of 4.5 hours for the ten concentrators compared. The other seven concentrators provide a battery life below the average. The most lightweight concentrator with the most lightweight battery provides only 1.5 hours of operation. There appears to be a significant trade-off for battery duration times and weight. Unfortunately both of these features are extremely important and difficult to give up either one.



Best Performing Pulse Oxygen Concentrator

The next most important feature to rank is the performance of the portable oxygen concentrator. Having the most lightweight concentrator with the longest power duration does little good if it is unable to provide sufficient oxygen to the patient. If a patient requires 10 liters of continuous flow oxygen per minute, none of these oxygen concentrators will be sufficient. In evaluating concentrator performance, we examined the maximum minute volume flow, the oxygen concentration output, the maximum outlet pressure and the operating altitude in feet above sea level for each machine. These four measurements provide a good look into the oxygen output capacity of each of these portable oxygen machines.

The Inogen G2 provides the highest minute flow volume at 1260 mL per minute (mL PM), the highest oxygen concentration level of 87 to 96% and the highest outlet pressure at 25 psi. The Inogen G3 and the Oxus also provide 87 to 96% concentration and the Inogen G2 also offers an outlet pressure of 25 psi. The FreeStyle 5 ranks second for minute volume at 936 mL PM while the Oxus ranks third at 850 mL PM. Several manufacturers were unable to provide us with the maximum outlet pressure, including AirSep, Invacare and Precision Medical. The Activox portable oxygen concentrators offer the highest operating altitudes of 0 to 13,000 feet above sea level. The AirSep Concentrators rank second for altitude operation with 0 to 12,000 feet. Comparing all four factors with the top ten portable concentrators, the Inogen G2 offers the best performance, achieving the number one designation in 3 categories--minute volume, oxygen concentration, and outlet pressure. The comparison chart below displays the four factors considered and the measurement for each concentrator.

Rank Model Pulse Oxygen Flow
(max minute volume mL)
Oxygen Outlet
(max psi)
Operating Altitude
(feet above sea level)
1 Inogen G2 1260 87 to 96% 25 0 - 10,000
2 FreeStyle 5 963 87 to 95.5% N/A 0-12,000
3 Oxus 850 87 to 96% 20.5 0 - 8,000
4 Inogen G3 840 87 to 96% 25 0 - 10,000
5 Invacare XPO2 840 87 to 95.6% N/A 0 -10,000
6 EasyPulse POC-5 780 87 to 95% N/A 0 - 9,000
7 FreeStyle 3 498 87 to 95.5% N/A 0-12,000
8 Activox Pro 480 87 to 93% 17.9 0-13,000
9 Activox 4L 480 87 to 93% 17.9 0-13,000
10 Focus 332 87 to 95.5% N/A 0-12,000


Ranking the Top Ten Portable Concentrators by Lowest Noise

Oxygen patients do not like to draw attention to the fact that they require oxygen therapy. A loud oxygen concentrator signals to the anyone nearby that you have a respiratory disability. An unobtrusive, quite concentrator is barely noticed. All of the top ten pulse flow POC's emit low levels of noise. 50 decibels and lower is considered by the Occupational Safety and Health Administration (OSHA) as safe and comfortable sound. Each of these portable oxygen concentrators fall in this comfortable zone. The concentrator emitting the least noise is the Inogen G2 at 38 decibels. As a comparison, a standard refrigerator in you home emits 30 decibels. The "noisiest" concentrator is the Activox Pro at 46 decibels, which is still at a very comfortable sound level. On the decibel chart below the lowest noise and the highest noise concentrators are plotted along the safe and non-hazardous Sound meter. Human conversation is at around 60 decibels while a refrigerator that is running emits around 30 decibel. Each of the top ten portable concentrators are in the safe, comfortable zone of the sound meter. These concentrators are below 50 decibels and well below the human conversation level of sound.


Portable Oxygen Concentrators with 24/7 Operation

24/7 operational capacity is an important feature for patients who travel and are away from their Home Oxygen Concentrator for an extended time. Only four of the ten pulse flow oxygen concentrators offer 24/7 operation. These concentrators are the Inogen G2, Inogen G3, Activox Pro and the Activox 4L. Activox does not recommend using their concentrators 24/7 for 365 days, indicating that excessive wear on the machines will occur. However, vacations of a few weeks duration can be accommodated by their portable concentrators.

Top Rated Concentrators with Extra Features

Manufacturers that provide extra features in concentrators are welcomed by oxygen patients. The EasyPulse POC-5 comes with an extra battery that extends the service time away from power outlets to 6.4 hours when operating at level 2. The Oxus Portable Oxygen Concentrator comes with a built-in O2 sensor. The AirSep FreeStyle 3 comes with a battery test button and with Braille soft-touch controls, making the FreeStyle 3 the only blind-friendly pulse flow portable. The SeQual Equinox is a combination continuous flow and pulse flow concentrator that is also blind-friendly with a multi-language voice function that speaks to you in your language of choice. The Inogen G3 offers the option to purchase their concentrator with either a long battery time 16 cell battery or a lightweight 8 cell battery.

Best Selling Pulse Flow Oxygen Concentrators

The best selling pulse flow portable oxygen concentrator at Vitality Medical is the Inogen G3. Its size, low-weight, performance and price have made it a popular choice since it was introduced a few years ago. Its sister product the G2, which is an older machine, also sells very well, ranking the second best selling portable concentrator. Even though it is an older concentrator, it out-performs the entire field for oxygen volume output as well as the lowest noise. The third best selling portable oxygen concentrator is the AirSep Focus which offers the lowest weight at a stunning 1.75 pounds as well as the smallest size.

Overall Best Portable Oxygen Concentrator Pulse Flow

The overall best portable oxygen concentrator is the Inogen G3 Oxygen Concentrator. This concentrator has the highest battery duration time, ranked in the top 4 for oxygen output, second for size, third for weight, and offers 24/7 service. The G3 also ranks number 1 (three-way tie: 87% to 96%) for oxygen concentration level and outlet pressure (two-way tie: 25 psi). Not surprisingly, it is also the best seller. The G3 option to use either a lightweight 8 cell battery or a long-lasting 16 cell battery is another outstanding feature. Oxygen patients are able to decide on the lower weight battery of 1.1 pounds less if they know they we be away from an external power source for less than 4 hours. If they will be away longer, they can use the 16 cell battery for 9.5 hours of operation. The second best overall concentrator is also from Inogen. The Inogen G2 Concentrator has the best oxygen output and lowest noise. Ranking third for the best overall portable concentrator is a tie between the AirSep Focus with its smallest size and lowest weight and the Oxus with its shared number 1 ranking for highest oxygen concentration, # 1 ranking for low power consumption and standard O2 oxygen sensor. Below are the top ten pulse flow oxygen concentrators and their comparative data.

Best Portable Oxygen Concentrator - The Top Pulse Flow Concentrator

Below is a detailed comparison chart displaying each of the comparative factors and the data for each portable oxygen concentrator.

Portable Oxygen Concentrator Pulse Flow Comparison Chart

Pulse Flow
Inogen One G2 Portable Oxygen Concentrator Oxus Portable Oxygen Concentrator Precisoin Medical EasyPulse5 Portable Oxygen Concentrator Invacare XPO2 Portable Oxygen Concentrator LifeChoice Activox Pro Portable Oxygen Concentrator LifeChoice Activox 4L Portable Oxygen Concentrator AirSep Focus AirSep FreeStyle 3 AirSep FreeStyle 5
Model Inogen
One G2
One G3
Oxus EasyPulse
Focus FreeStyle 3 FreeStyle 5
Model # IS200 IS-300-NA RS-00410 PM4150 XPO100 XYC100B-PRO AOX-P4L-USRA AS078-1 FREESTYLE3 FREESTYLE5
Manufacturer Inogen Inogen Oxus Precision Medical Invacare Inova Labs Inova Labs AirSep AirSep AirSep
Pulse Oxygen Flow
(max minute volume mL)
1260 840 850 380 840 480 480 332 498 963
Oxygen Concentration 87 to 96% 87 to 96% 87 to 96% 87 to 95% 87 to 95.6% 87 to 93% 87 to 93% 87 to 95.5% 87 to 95.5% 87 to 95.5%
Oxygen Outlet Pressure
(max psi)
25 25 20.5 N/A N/A 17.9 17.9 N/A N/A N/A
Operating Altitude
(feet above sea level)
0 - 10,000 0 - 10,000 0 - 8,000 0 - 9,000 0 -10,000 0-13,000 0-13,000 0-12,000 0-12,000 0-12,000
10.7 8.75 7.6 6.5 7 9.05 9.05 4.8 6.1 6.4
9.5 7.25 11.9 10.1 10 7.875 7.875 6.4 8.6 10.5
3.9 3 5.6 4.5 4 4.38 4.38 2.5 3.6 4.4
Cubic Size
396.44 190.31 506.46 295.43 280.00 312.16 312.16 76.80 188.86 295.68
Weight with Battery
7 4.8
(8 cell battery)
(16 cell battery)
9.9 6.8 6.4 4.83 4.83 1.75 4.4 5.8
Operating Factors                    
(On Setting 2)
38 42 43 44 42.7 46 44 45 41 41
Power Connections Worldwide Sensing 100-240VAC or 12VDC Worldwide Sensing 100-240VAC or 12VDC 100-240V AC (± 10%), 50-60 Hz; battery power 18V DC, 6.7 amps; DC adaptor 100 to 240 VAC / 1 Amp
11 - 16 VDC/ 5 Amp
100-240VAC or 12VDC AC 100-240 VAC; 50-60 Hz Cycles; DC 12-19 VDC or Battery 12-16.8 VDC AC 100-240 VAC; 50-60 Hz Cycles; DC 12-19 VDC or Battery 12-16.8 VDC 100 - 240 VAC, 50.60 Hz 11-16 VDC 100 - 240 VAC, 50.60 Hz, 1 AMP 11-16 VDC, 6 AMP 100 - 250 VAC, 50.60 Hz 11-16 VDC
Average Power Consumption (watts) 110 110 100 120 35 120 120 180 210 240
Battery 12 Cell
Lithium Ion
8 Cell
Lithium Ion
16 Cell
Lithium Ion
12 Cell
Lithium Ion
Lithium Ion 1 Cell
Lithium Ion
Lithium Ion (Internal) Lithium Ion (Internal) Lithium Ion Lithium Ion Lithium Ion
Battery Duration with Full Charge
(Pulse, at setting 2, # hours)
4 4
(8 cell battery)
(16 cell battery)
4 3.2 2.5 7.25 8.25 1.5 2.5 2
Battery Recharge Time
4 4
(8 cell battery)
(16 cell battery)
3 2 to 4 4 4 4 3 3.5 3.5
24/7 Operation
No No No Yes Yes No No Yes Yes No
Preventive Maintenance Check
(after # hours)
20,000 20,000 N/A N/A 4,320 N/A N/A N/A N/A N/A
Made In The USA Yes Yes N/A Yes USA
Yes Yes Yes
Compressor Maintenance
(after # hours)
20,000 20,000 - 30,000 N/A N/A N/A N/A N/A N/A N/A N/A
FAA Approval Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Warranty 1 yr, 3 yr
or lifetime limited
3 yrs 3 yrs 3 yrs 3 yrs 3 yrs 3 yrs 3 yrs 3 yrs 3 yrs

Burt Cancaster, Author

Vitality Medical
7910 South 3500 East, Suite C
Salt Lake City, UT 84121
(801) 733-4449
[email protected]

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