1L and 2L oxygen concentrator belongs to the health care type, the air flow mediation in 1L/MIN, the oxygen concentration can reach 90%. But for patients, the airflow is small.
The 3-liter and 5-liter oxygen concentrators belong to the medical type. Patients must use either the 3-liter or 5-liter.
When the air flow of 3-liter machine is adjusted to 3L/MIN, the concentration of oxygen can reach more than 95%.
For patients, the air flow is also enough. 5-liter machine is usually used by two people at the same time or with the ventilator.