Respiratory / Reference

Oxygen Delivery Device FiO₂ Chart: Nasal Cannula, Simple Mask, Venturi and Reservoir

June 1, 2026 · 8 min read · Edaochi Medical

How much FiO₂ does each oxygen device deliver, and at what flow? This is the reference chart linking the system (nasal cannula, simple mask, Venturi mask and non-rebreather/reservoir mask), the flow in litres per minute and the approximate FiO₂, with when to use each. It complements our nasal cannula oxygen therapy guide and the complete nasal cannula guide.

FiO₂ by device and flow (chart)

Devices split into low flow (FiO₂ depends on the patient's breathing pattern) and high flow / controlled FiO₂ (a more fixed FiO₂). Approximate values:

Device	Flow (L/min)	Approx. FiO₂	Type
Nasal cannula	1–6	24–44 %	Low flow
Simple mask	6–10	40–60 %	Low flow
Venturi mask	per adaptor	24–60 % (fixed)	Fixed performance
Non-rebreather (reservoir) mask	10–15	80–95 % (up to ~100 %)	High delivery
High-flow nasal cannula (HFNC)	up to 60	21–100 % (adjustable)	High flow

Nasal cannula: each litre adds ≈4 % to the baseline FiO₂ (21 %). Above 6 L/min it adds no more and dries the mucosa.

Simple mask: needs a minimum of 5–6 L/min to flush exhaled CO₂ from inside the mask.

Venturi: uses colour-coded adaptors that fix the FiO₂ (e.g. 24, 28, 31, 35, 40, 50 %) at the flow marked on each adaptor. It is the best choice when an exact FiO₂ is needed, as in the COPD patient.

Reservoir (non-rebreather): the bag must stay inflated; flow (10–15 L/min) is set so it does not collapse on inspiration. It delivers the highest FiO₂ without high-flow equipment.

High-flow nasal cannula (HFNC): delivers heated, humidified air/oxygen at high flows (up to 60 L/min) with an adjustable FiO₂ from 21 to 100 %; it needs dedicated equipment (not the conventional cannula). Useful in hypoxaemic respiratory failure as a step before ventilation.

When to use each device

Nasal cannula: low oxygen needs, stable patient, home care; lets the patient eat and talk.
Simple mask: moderate need when the cannula cannot reach the target saturation.
Venturi mask: when a precise, constant FiO₂ is needed, especially in COPD and other patients in whom over-oxygenation should be avoided.
Non-rebreather mask: emergencies and severe hypoxaemia requiring the highest possible FiO₂ while the next step is decided.

The usual target SpO₂ is 94–98 %, and 88–92 % in patients at risk of CO₂ retention. The device and flow are set by the prescription against that target.

What to check when buying oxygen devices wholesale

For clinics, hospitals and home-care providers:

Adult and paediatric sizes across all masks, with a comfortable cushion/fit and an elastic band that does not mark the skin.

Universal connector and tubing compatible with flowmeters, humidifier bottles and concentrators; kink-resistant tubing of suitable length (bed vs mobility).

Non-rebreather mask: intact one-way valve and a good-volume bag to maintain a high FiO₂.

Latex-free material, transparent to watch for secretions, EO sterilisation if applicable.

Certification and traceability: CE / ISO 13485, lot traceability and national registration as required by destination. Request samples before quoting volume.

Frequently Asked Questions

How much FiO₂ does each oxygen device deliver?

Approximately: nasal cannula 24–44 % (1–6 L/min), simple mask 40–60 % (6–10 L/min), Venturi mask 24–50 % at a fixed FiO₂ set by the adaptor, and non-rebreather mask 80–95 % (10–15 L/min). Low-flow devices give a FiO₂ that depends on the breathing pattern; the Venturi delivers a more exact FiO₂.

What is the minimum flow for a simple oxygen mask?

At least 5 to 6 L/min. Below that, exhaled CO₂ trapped inside the mask is not flushed and the patient rebreathes it. If little oxygen is needed, a nasal cannula is preferable.

When is a Venturi mask used?

When a precise, constant FiO₂ is needed, especially in COPD patients in whom giving more oxygen than necessary should be avoided. It uses colour-coded adaptors that fix the FiO₂ (for example 24, 28, 31, 35, 40 or 50 %) at the flow marked on each adaptor.

Which mask gives the most oxygen?

The non-rebreather (reservoir) mask, which at 10–15 L/min delivers a FiO₂ of 80–95 %. For it to work, the reservoir bag must stay inflated and not collapse during inspiration. It is used in emergencies and severe hypoxaemia.