If you're new to oxygen therapy, "flow rate" is probably one of the first terms you'll hear — and one of the most confusing. The honest answer to "what flow rate do I need" isn't something a blog post, a product page, or even a knowledgeable friend can give you. It's a medical decision made by your doctor, based on your own blood oxygen levels. What this guide can do is explain what flow rate actually means, how your doctor arrives at that number, and how to make sense of it once you're choosing a concentrator.
Why Does Oxygen Flow Rate Matter?
Choosing an oxygen concentrator is not simply about finding the machine with the highest number of settings.
The important question is whether the machine's delivery method and available settings match your individual requirements.
A concentrator can use:
-
Continuous flow: Oxygen is delivered continuously while the machine is operating.
-
Pulse flow: Oxygen is delivered in pulses, typically triggered by inhalation or according to a fixed pulse pattern.
-
Dual pulse modes: Some portable models offer breath-sensing and automatic/fixed-frequency pulse delivery.
Because these delivery methods work differently, a pulse-flow setting should not automatically be considered equivalent to a continuous-flow L/min setting.
How Is Oxygen Flow Rate Measured?
Continuous Flow: Liters Per Minute
Continuous-flow oxygen concentrators are generally described using L/min.
For example:
| Continuous Flow |
Example |
| 1 L/min |
Lower continuous-flow setting |
| 2 L/min |
Continuous oxygen delivery |
| 3 L/min |
Continuous oxygen delivery |
| 4 L/min |
Continuous oxygen delivery |
| 5 L/min |
Higher continuous-flow setting |
A machine advertised as 1–5 L/min means the device provides adjustable continuous oxygen flow within that range.
However, the maximum flow of a machine does not mean that maximum setting is appropriate for every user.
Pulse Flow: Numbered Settings
Portable pulse-flow concentrators commonly use numbered settings such as:
These settings represent the device's pulse-delivery levels. They should not automatically be converted into L/min.
For example, the VARON VP-8G has 1–8 pulse-flow settings, while the VP-8 Lite has 1–7 pulse-flow settings. (VARON)
Who Determines Your Appropriate Oxygen Flow?
Your appropriate oxygen flow or delivery setting should be determined according to your individual oxygen requirements.
A qualified healthcare professional can help determine:
- The appropriate oxygen delivery method
- The appropriate flow or setting
- Whether continuous or pulse flow is appropriate
- When the setting should be used
- Whether the setting needs to change during different activities
- Whether the equipment is compatible with other breathing equipment
Do not choose an oxygen setting simply because it is the highest setting available on a machine.
Can Oxygen Needs Change During the Day?
Oxygen requirements can vary depending on the situation.
For example, a person may use oxygen while:
- Resting
- Walking around the home
- Doing household activities
- Spending time outdoors
- Sleeping
- Traveling
However, changes in activity do not automatically mean that you should change your oxygen setting yourself.
If you notice that your oxygen needs appear different during rest, activity, or sleep, discuss those changes with a qualified healthcare professional.
Continuous Flow vs. Pulse Flow Oxygen
Understanding this difference is important when choosing an oxygen concentrator.
| Feature |
Continuous Flow |
Pulse Flow |
| Delivery |
Oxygen flows continuously |
Oxygen delivered in pulses |
| Common measurement |
L/min |
Numbered settings |
| Common design |
Home and portable models |
Primarily portable models |
| Mobility |
Available in home and portable designs |
Commonly designed for mobility |
| Battery operation |
Available on some portable models |
Common on portable models |
| CPAP/BiPAP considerations |
Generally preferred when supplemental oxygen is used with PAP equipment |
Should not automatically be assumed compatible |
Continuous and pulse flow are different delivery methods, so the setting on one type of machine cannot simply be compared numerically with the setting on another.
What Is the Difference Between Oxygen Flow and Oxygen Concentration?
These two specifications are often confused.
Oxygen Flow
Flow describes how oxygen is delivered.
For continuous-flow devices, it is expressed in L/min.
Oxygen Concentration
Oxygen concentration describes the percentage of oxygen in the output under specified operating conditions.
For example, the VARON Serene 5 is listed at 93% ±3% across its adjustable 0.5–5 L/min continuous-flow range.
The Serene 3, meanwhile, provides 93% ±3% at 1–3 L/min, with concentration specified up to 80% ±3% at 4–10 L/min.
This is why it is important to read both flow range and oxygen concentration specifications instead of looking at only one number.
VARON US Oxygen Concentrator Flow Options
The current VARON US lineup includes both continuous-flow and pulse-flow oxygen concentrators.
| VARON Model |
Delivery Type |
Flow / Settings |
Oxygen Concentration |
| Serene 5 |
Continuous |
0.5–5 L/min |
93% ±3% |
| Serene 3 |
Continuous |
1–10 L/min |
93% ±3% at 1–3 L/min; up to 80% ±3% at 4–10 L/min |
| VH-2 Pro |
Continuous |
1–8 L/min |
93% ±3% at 1–2 L/min; 35% ±3%–78% ±3% at 3–8 L/min |
| VH-4 |
Continuous |
1–9 L/min |
90% at 1 L/min, decreasing with higher flow |
| VH-3 |
Continuous |
1–7 L/min |
28%-90%(Adjustable)
|
| VH-2 |
Continuous |
1–7 L/min |
35%–90% |
| VH-1 |
Continuous |
1–7 L/min |
30%–90% |
| VP-6 |
Continuous |
1–6 L/min |
93% ±3% at 1 L/min |
| VL-2 |
Continuous |
3 L/min |
30% ±2.5% |
| VP-8G |
Pulse
|
1–8 settings |
93% ±3% |
| VP-8 Lite |
Pulse |
1–7 settings |
90% |
| VP-2 |
Pulse |
1–5 settings |
93% ±3% |
| VP-1 |
Pulse |
1–5 settings |
93% ±3% |
| VL-1 |
Pulse |
Maximum equivalent output 3 L/min |
32.5% ±2.5% |
The specifications above reflect the current VARON US product information available for these models.
Important: The numbers in a pulse-flow column are settings, not equivalent continuous-flow L/min values.
For home use, continuous-flow models can be useful when you need a machine designed around adjustable continuous oxygen delivery.
The VARON Serene 5 provides continuous flow from 0.5–5 L/min with 93% ±3% oxygen concentration across its adjustable flow range. It also includes a humidification system, nebulizer function, LCD display, and caster wheels.
Its design is intended for stationary home use where users may value:
- Continuous-flow capability
- Long-duration operation
- Easy movement around the home
- Lower operating noise
- Integrated humidification and nebulizer functions
The VARON Serene 3 provides adjustable continuous flow from 1–10 L/min. Its oxygen concentration is specified at 93% ±3% from 1–3 L/min and up to 80% ±3% at 4–10 L/min.
This makes the flow specification particularly important when comparing it with models that maintain a stated concentration across their entire flow range.
The VH-2 Pro provides continuous flow from 1–8 L/min. Its specifications should also be read by flow range rather than summarized as one oxygen-concentration figure across all settings.
If mobility is important, portable models provide a different combination of delivery method, size, battery operation, and carrying convenience.
The VP-8G provides:
- 1–8 pulse-flow settings
- 93% ±3% oxygen concentration
- 4.37 lb weight with battery
- Up to 4 hours of battery life
- Replaceable battery
- AC and car-power options
- Noise level ≤40 dB at level 1
The VP-8 Lite provides:
- 1–7 pulse-flow settings
- 90% oxygen concentration
- 4.4 lb weight
- 1.5–5 hours battery working time
- Replaceable battery
- Breath-sensing and fixed-frequency pulse modes
- AC and car-power options
The VP-6 is different from the VP-8G and VP-8 Lite because it uses continuous flow, with adjustable delivery from 1–6 L/min. VARON lists 93% ±3% oxygen concentration at 1 L/min.
This distinction matters if you are specifically looking for a portable continuous-flow design rather than a pulse-flow portable model.
What About Oxygen Flow for CPAP or BiPAP?
If an oxygen concentrator is being used with CPAP or BiPAP, continuous-flow oxygen is generally preferred over pulse flow because PAP equipment operates continuously while you breathe during sleep.
Pulse-flow delivery should not automatically be assumed to provide the appropriate oxygen delivery when sleeping with PAP equipment.
If you plan to combine a CPAP or BiPAP machine with an oxygen concentrator, consult a qualified healthcare professional before connecting the equipment or changing any settings. The appropriate setup can vary from person to person.
For this type of use, focus on continuous-flow capability and confirmed equipment compatibility, rather than simply choosing the smallest or lightest portable concentrator.
Common Mistakes When Choosing an Oxygen Flow Rate
1. Choosing the highest available setting
A concentrator offering 1–10 L/min does not mean you should use 10 L/min.
The available range describes what the machine can provide, not what every user should select.
2. Treating pulse settings as L/min
A pulse setting of 5 is not automatically equivalent to 5 L/min continuous flow.
Pulse and continuous systems deliver oxygen differently.
3. Looking only at oxygen concentration
A product may advertise a high oxygen concentration, but you should also check the flow range at which that concentration is specified.
4. Choosing only by portability
A lightweight concentrator may be convenient to carry, but portability should not be the only consideration.
Consider:
- Delivery method
- Available flow/settings
- Oxygen concentration specifications
- Battery operation
- Power options
- Weight
- Noise
- Intended use
5. Changing settings without professional guidance
If your oxygen needs seem to change, speak with a qualified healthcare professional rather than adjusting the setting based only on how you feel.
How to Choose the Right VARON Oxygen Concentrator
Instead of asking only “What is the highest flow rate?”, consider these questions:
Do I need continuous or pulse flow?
This is one of the most important differences between VARON home and portable models.
Do I need a stationary or portable machine?
Home models generally prioritize continuous operation and household convenience, while portable models emphasize mobility, battery operation, and carrying weight.
What flow or setting range do I need?
Compare your required setting with the manufacturer's actual specifications.
What oxygen concentration is specified at that flow?
Do not assume the listed concentration applies equally across every setting.
Will I use the concentrator with CPAP or BiPAP?
If so, confirm that the equipment and connection setup are appropriate with a qualified healthcare professional.
Frequently Asked Questions
What is a normal oxygen flow rate?
There is no single flow rate that is appropriate for everyone. The appropriate oxygen flow or pulse setting depends on individual oxygen requirements and should be determined with guidance from a qualified healthcare professional.
Is 2 L/min a high oxygen flow rate?
2 L/min is a continuous-flow measurement, but whether it is appropriate depends on the individual and the intended use. It should not be classified as “high” or “low” without that context.
Is pulse setting 5 the same as 5 L/min?
No. Pulse-flow settings and continuous-flow L/min measurements describe different oxygen-delivery methods and should not be treated as equivalent.
What is the difference between continuous and pulse flow?
Continuous flow delivers oxygen continuously, while pulse flow delivers oxygen in timed or breath-triggered pulses.
Which VARON oxygen concentrators use continuous flow?
VARON's US lineup includes continuous-flow models such as the Serene 5, Serene 3, VH-2 Pro, VH-4, VH-3, VH-2, VH-1, VP-6, and VL-2.
Which VARON portable models use pulse flow?
The VP-8G, VP-8 Lite, VP-2, VP-1, and VL-1 use pulse-flow delivery.
Can I increase my oxygen flow if I feel I need more?
Do not change your oxygen setting simply because you feel that you need more. Discuss changes in oxygen needs with a qualified healthcare professional.
Can I use a pulse-flow concentrator with CPAP?
Pulse flow should not automatically be assumed to be suitable for CPAP. When supplemental oxygen is used with CPAP or BiPAP, continuous-flow equipment is generally preferred, and compatibility should be confirmed with a qualified healthcare professional.
Final Thoughts
Choosing an oxygen concentrator starts with understanding the difference between flow rate, oxygen concentration, and delivery method.
For continuous-flow models, pay attention to the stated L/min range and oxygen concentration at each flow range. For pulse-flow models, remember that numbered settings are not equivalent to continuous-flow L/min.
VARON's US lineup includes both home continuous-flow and portable pulse- or continuous-flow options, allowing users to compare specifications based on their individual requirements and intended use.
Before selecting or changing an oxygen setting, discuss your individual oxygen requirements with a qualified healthcare professional.
Explore VARON Oxygen Concentrators
From stationary home models such as the Serene 5 and Serene 3 to portable options such as the VP-8G, VP-8 Lite, and VP-6, VARON offers different flow and delivery configurations for different use scenarios.
Shop VARON Oxygen Concentrators:
VARON US Oxygen Concentrators
Note: Oxygen concentrator settings should be selected according to individual oxygen requirements and guidance from a qualified healthcare professional.
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