When you press the power button on a portable oxygen concentrator (POC), it can seem almost magical. Air goes in, and clean, therapeutic oxygen comes out. Behind this smooth process, though, is a careful combination of engineering, chemistry, and control systems working together many times each minute. 

At LPT Medical, it helps both users and caregivers to understand what happens inside the device. Here, we’ll walk you through each step of what really happens when you turn on a portable oxygen concentrator.

1. Intake: Sucking in Ambient Air

It all starts with the air around you, which is about 78% nitrogen, 21% oxygen, and small amounts of other gases. When you turn the POC on, the first step is to pull that air into the system through an intake filter.

• The intake filter’s job is to trap dust, pollen, and larger particulates to protect downstream components.
• After filtering, the air enters a compressor stage.

This simple act of drawing in air is critical: if the unit can't pull in a clean, adequate volume of ambient air, performance will suffer.

2. Compression: Increasing Pressure

Once inside, the air is pressurized by a miniaturized compressor. This step is essential because the separation process that follows relies on pressure differentials.

By compressing the air, the system increases the partial pressures of gases, allowing molecular sieves (explained next) to discriminate between nitrogen and oxygen more effectively.

At this stage, the compressed air still contains all its original gases and has not yet been purified.

3. Separation via Molecular Sieve: Removing Nitrogen

This is where the real “concentration” takes place. The central part of a POC uses pressure swing adsorption (PSA), often in a rapid, fast-cycling mode, to separate oxygen from nitrogen.

Here’s how:

• Inside the POC are two or more vessels (sieve beds) filled with zeolite pellets (a crystalline aluminosilicate). These act as molecular sponges that “adsorb” nitrogen molecules more strongly than oxygen.
• The system sends compressed air into one sieve bed, trapping nitrogen within the zeolite and allowing oxygen (along with trace gases) to pass.
• Meanwhile, the other sieve bed is releasing previously trapped nitrogen (a process called desorption) into the atmosphere, flushing and reactivating the bed.

By switching between beds in quick cycles, often many times each minute, the device keeps a steady supply of oxygen. This back-and-forth process is a key feature of PSA operation. 

Some POCs may use enhanced control algorithms (for example, variable bolus sizing) to adapt to a user’s breathing rate.

4. Oxygen Accumulation & Reservoir

After passing through the sieve bed, the enriched oxygen is directed to a small internal reservoir, or buffer tank. This provides a small cushion and helps keep the flow steady as the sieve beds switch.

The reservoir ensures that oxygen delivery remains steady, even as the system switches between beds or continues at the selected rate. 

From the reservoir, oxygen is then passed through downstream lines and ultimately delivered through your nasal cannula or mask.

5. Delivery: Pulse Versus Continuous Flow

The way oxygen reaches your lungs depends on the POC’s delivery mode. Most portable units use pulse dose (on-demand) delivery, while some can also provide continuous flow for people who need more oxygen.

• Pulse Dose / On-Demand: The device senses the start of an inhalation and quickly releases a bolus of oxygen (measured in milliliters per breath). This approach conserves oxygen and battery life, since oxygen is only delivered when you breathe in.
• Continuous Flow: Oxygen is delivered continuously, regardless of your breathing cycle. This is useful (or required) for users who need higher flows or during sleep, when triggering may not be reliable.

Some advanced POCs offer hybrid or “both modes” to adapt to user needs.

In pulse mode, the device’s electronics monitor your breathing and release the oxygen at just the right moment. The timing has to be quick and accurate. If it’s too early, the oxygen is wasted. If it’s too late, you might not get the oxygen you need in time.

6. Exhaust & Purging

Meanwhile, the nitrogen-laden gas rejected by the zeolite beds must be purged. In each cycle:

• The bed that was absorbing nitrogen is depressurized.
• Residual nitrogen (and some oxygen) is vented into the atmosphere.
• The bed is “flushed” or “rinsed” to strip away remaining nitrogen, preparing it for the next adsorption cycle.

This venting is typically quiet, timed to avoid fluctuations in oxygen delivery.

Thanks to this recycling, the system stays small and lightweight, which is important for portability.

7. Power, Control & Safety Checks

Of course, all of this happens under the control of a microprocessor that:

• Manages the timing of the compressor and bed cycling
• Monitors pressure, flow, oxygen purity sensors, and system health
• Detects breathing to trigger pulse doses
• Issues alarms if oxygen purity, pressure, or flow falls out of spec
• Monitors battery or external power supply

This system needs a steady power source, usually a rechargeable battery (lithium-ion) or AC power, and sometimes a car adapter for travel. Battery life depends a lot on the flow rate, delivery mode, and how often you breathe.

Safety features like over-temperature shutdown, flow monitors, and alarms help protect the user. Additionally, the oxygen firebreak is a thermal fuse built into the oxygen tubing near the patient's side; if a tubing fire occurs (e.g., from an external spark), it stops oxygen flow and isolates the system to prevent propagation.

8. Warm-Up & Stabilization

When you first turn on the POC, there is a brief warm-up phase:

• The compressor spins up, pressure builds, and the sieve beds begin their cycles.
• The oxygen purity and flow are calibrated.
• The internal reservoir fills and stabilizes.

During this time, you might notice a short delay before the device reaches your full prescribed output, or you may see small changes in flow or pressure. This is normal and means the internal systems are getting in sync.

9. Real-World Challenges & Optimizations

Even the best POCs have to deal with real-world challenges, and engineers have developed innovative solutions to address them:

• Altitude & Ambient Pressure: At high altitudes or low atmospheric pressure, separations become harder, so devices may adjust duty cycles or pressure settings to maintain output.
• Breath Variability: Your breathing pattern changes with activity or rest. High-end POCs may dynamically adjust bolus size to match.
• Temperature & Humidity: Heat or moisture can reduce the efficiency of zeolite beds and compressors; cooling or moisture-control strategies are essential.
• Battery Efficiency & Load Management: Because power is precious in portable devices, every subsystem is optimized to minimize power consumption.
• Wear & Maintenance: Zeolite beds degrade and filters clog over time; regular maintenance ensures consistent performance.

10. Why This Matters for You (and LPT Medical’s Users)

Learning how a POC works is not just for curiosity. It has real benefits:

• Expectations & Trust: Knowing how your device works reinforces confidence that it's doing the job you—or your physician—relied on it to do.
• Troubleshooting: If alarms sound or output falters, knowledge of the system flow helps you identify whether the issue is an intake blockage, a battery issue, a tubing kink, or an internal fault.
• Optimizing Use: Recognizing that pulse mode is more power-efficient, but that continuous mode may be necessary during sleep, helps you plan battery usage and backup strategies.
• Safety Awareness: Awareness of firebreaks, ventilation, and keeping the device away from flammables becomes more intuitive when you know oxygen concentration and pressure are actively modulated.
• Informed Questions: You can better engage with your provider or supplier about modes, flow settings, battery options, and the expected maintenance schedule.

At LPT Medical, we aim not only to provide top-tier devices but also to educate users so they can get the most from their oxygen therapy. Whether you're a longtime user, a caregiver, or considering adding a POC to your medical plan, we want you to feel confident about the science beneath the surface.

Final Thoughts

When you turn on a portable oxygen concentrator, you are starting a carefully balanced process of chemistry and mechanics. The device draws in air, compresses it, filters it through zeolite beds, removes nitrogen, and delivers oxygen to your lungs. This all happens in moments and repeats many times each minute.

That “invisible” complexity is what enables mobility, safety, and continuous oxygen delivery without relying on heavy tanks. As engineers, clinicians, users, and caregivers, appreciating the inner workings shows respect for the design, provides insight into maintenance, and builds confidence in daily use.

If you have questions about a specific model, how your settings affect you, or want help troubleshooting alerts or developing efficiency strategies, LPT Medical is here to support you. CALL 800-946-1201! Transparency and knowledge are the best companions to life-sustaining devices.