1. Separate the Key Oxygen Specifications

Also ask how flow is reported. Standard liters per minute and actual liters per minute at chamber pressure use different reference conditions. A flowmeter reading needs to be interpreted according to its calibration and installation.

2. Read Purity and Flow Together

PSA oxygen concentrators use molecular sieves to separate much of the nitrogen from air. Their oxygen concentration must be checked within the rated flow range and operating conditions.

For example, CAIRE lists NewLife Intensity 10 purity as 92% +3.5/−3% at 2–9 LPM and 90% +5.5/−3% at 10 LPM. This is a specification-reading example, not confirmation that the unit matches a particular chamber.

Do not assume every concentrator loses purity as flow increases. Instead, ask for the verified range at the intended setting, including warm-up time, temperature, altitude and power requirements.

• Is the advertised purity a typical value or a guaranteed range?

• What concentration is specified at maximum rated flow?

• Does the device include a low-oxygen alarm, and what triggers it?

3. Match Supply Pressure to Chamber Back Pressure

When an external source supplies oxygen to a breathing interface inside an air-pressurized chamber, it must overcome chamber pressure and the pressure losses in the tubing, valves and interface.

These rounded values assume outside pressure is 1 atmosphere. At altitude, gauge pressure depends on local atmospheric pressure and how the chamber setpoint is defined.

A maximum outlet-pressure rating does not tell you the flow available at that pressure. Request a flow-versus-back-pressure curve or test results for the complete configuration at its working pressure.

4. Continuous Flow and Demand BIBS Need Different Checks

Continuous-flow systems supply gas throughout the breathing cycle. Their performance depends on flow, reservoir capacity, interface design, leakage and breathing demand.

Demand-valve systems supply gas when the user inhales. They require checks for supply pressure, peak flow, inhalation trigger, pressure compensation and exhalation resistance. Average source flow alone cannot establish compatibility.

BIBS stands for Built-In Breathing System. The name does not, by itself, confirm whether delivery is continuous or demand-controlled. Ask for the actual system design.

For an air-pressurized chamber, the compressor pressurizes the cabin while the oxygen source supplies the breathing interface. Confirm whether exhaled gas is discharged outside the chamber, and review the approved masks, valves and hoses.

5. Verify Capacity with Both Stations Running

Two outlets do not automatically double the source capacity. CAIRE’s NewLife Intensity 10 dual-flow option allows combinations totaling up to 10 LPM. Two outlets set to 5 LPM each share that total.

For a two-person chamber, request results with both breathing stations active at the target chamber pressure. Check:

• Total flow and available flow at each station.

• Oxygen concentration during simultaneous operation.

• Whether adjusting one station affects the other.

• Peak supply capacity for demand-controlled systems.

• Each station’s exhaled-gas pathway.

Whether the system uses shared or separate oxygen sources, its capacity needs configuration-specific verification.

6. Know What Each Oxygen Measurement Means

Source purity, breathing-interface concentration and cabin oxygen concentration are different measurements.

For a dry gas mixture, oxygen partial pressure equals absolute pressure multiplied by oxygen fraction. At 2.0 ATA, a verified 93% mixture would have a theoretical dry-gas oxygen partial pressure of 1.86 ATA.

This calculation does not establish actual inhaled concentration, blood oxygen, tissue oxygen or treatment results. Follow the device instructions for monitoring, operation and maintenance.

7. Ask for a Test Report You Can Actually Use

A useful report identifies the equipment and conditions behind the numbers:

• Chamber, oxygen-source and breathing-interface models.

• Tubing length, diameter, valves and supply configuration.

• Working pressure, flow settings and active stations.

• Measurement locations and flow reference conditions.

• Temperature, altitude, power supply and test duration.

• Instrument details, calibration and acceptance criteria.

If working-pressure flow or mask-side concentration has not been tested, label it “not yet verified”. Do not replace missing measurements with estimates from the source nameplate.

8. Supplier Checklist and FAQs

Is higher purity more important than higher flow?

Neither should be judged alone. The source must provide the specified concentration and enough flow at the required pressure for the matched breathing system.

Can one concentrator supply two users?

Possibly, if the complete system is approved and verified for simultaneous use. Two outlet ports alone are not enough evidence.

Does “BIBS compatible” prove the setup will work?

No. Ask which BIBS model, supply pressure, chamber pressure and operating conditions were used for verification.

What information helps a supplier recommend a system?

Provide the chamber model, target pressure, user count, breathing-interface requirements, destination and electrical supply.