The regulator (sometimes called the adjustable regulator, flowmeter, or control valve) reduces, controls, and measures the flow of oxygen to the patient to ensure a safe and effective working pressure. The regulator and flowmeter usually are coupled together into one mechanical fitting on the oxygen tank.

Oxygen regulators come in two basic types: continuous flow and conserver.

1. Continuous flow provides a steady flow of oxygen while a patient is on portable cylinders.
2. Conservers shut off O2 supply while the patient is exhaling, conserving oxygen and may allow for additional cylinder duration time depending on circumstances.

In most conditions, an oxygen saturation of 94–96% is adequate, while in those at risk of carbon dioxide retention, saturations of 88–92% are preferred.