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An oxygen regulator is the device between a compressed oxygen cylinder and the equipment that delivers oxygen to a patient. It lowers the high cylinder pressure to a low, usable outlet pressure and, on many models, also sets or shows the flow. This page describes products and general use; it is not medical advice.
Who uses it: clinic and hospital staff who set up cylinder oxygen, biomedical and procurement teams who specify equipment, and students learning medical gas systems. The figures below come from the WHO-UNICEF technical specifications for oxygen therapy devices and from the scope of the ISO 10524-1 standard, both linked in the Sources section at the end.
What an oxygen regulator is
An oxygen regulator (also called a pressure regulator or pressure-reducing valve) is the pressure-control component of a cylinder oxygen set-up. A full cylinder holds oxygen at very high pressure; the regulator reduces that to a fixed, much lower pressure that downstream tubing and flow devices are built to handle. ISO 10524-1:2019, the international standard for these devices, covers pressure regulators and pressure regulators with flow-metering devices intended for administering medical gases and mixtures such as oxygen, medical air and oxygen/nitrous oxide mixtures.
Some cylinders have a built-in integral regulator, so no separate regulator is needed.
How an oxygen regulator is built
The WHO-UNICEF specification for the cylinder pressure regulator assembly describes these parts and features:
- Inlet connection: the regulator must be compatible with the cylinder’s primary valve, either a pin index or a bullnose type.
- Body and valve materials: casing of steel, plated brass or aluminium, with a brass valve.
- Pressure gauge: an integrated manometer reading 0 to 20 000 kPa, so the user can see cylinder pressure.
- Outlet: available with a DISS connector or a 6 mm barbed outlet. DISS connectors are threaded, with a diameter unique to each gas.
- Flow control (optional): a basic open/close model, or one with an integrated Thorpe tube or Bourdon flowmeter.
Versions exist for oxygen and for medical air, and in standard and MRI-compatible forms.
The Pin Index Safety System is a key safeguard: the arrangement of the pins is unique for each gas, to prevent the use of the wrong gas. For the cylinder side of the connection, see CASRAI’s entries on CGA fittings and compressed gas cylinder sizes.
Types and variants: how the flow control differs
The main difference between regulator models is how flow is set and shown. WHO-UNICEF compares three flowmeter types (its Table 4.1), and the choice decides whether a separate pressure-reducing valve is needed at all.
| Flowmeter type | How it works | Pressure-reducing valve | Orientation and accuracy notes |
|---|---|---|---|
| Thorpe tube | Variable orifice; a float moves in a clear upright tube | Requires a separate pressure-reducing valve | Must be kept vertical; works from a 345 kPa source only |
| Bourdon gauge | Fixed orifice | Integrates a pressure-reducing valve | Unaffected by gravity and usable at any angle (emergency and transport use); not back-pressure compensated; less accurate at low flows |
| Dial / click-type | Fixed orifice | Integrates a pressure-reducing valve | Regulates flow but does not measure it; accurate only at its rated pressure (345 kPa) |
WHO-UNICEF also notes that a preset regulator with one low-pressure gauge is recommended as the first choice in low-resource settings, while an adjustable regulator with a double gauge (high and low pressure) gives more options but adds complexity.
Specifications that matter
| Specification | WHO-UNICEF value |
|---|---|
| Nominal inlet pressure | 13 700 kPa (137 bar, 1987 psi) |
| Maximum inlet pressure | 20 000 kPa (200 bar, 2901 psi) |
| Outlet pressure | 345 kPa (3.45 bar, 50 psi) |
| Integrated gauge range | 0 to 20 000 kPa |
| Standard cylinder nominal pressure | 13 700 kPa |
| Integral-valve cylinder pressure | 23 000 to 30 000 kPa |
| Low flow range (oxygen only) | 0 to 3 or 4 L/min, accuracy 10% |
| Standard flow ranges | 0 to 7/8 and 0 to 15/16 L/min (Thorpe or Bourdon), accuracy 10% |
| High flow range | At least 0 to 25 L/min, accuracy 10% |
| Dial-style ranges | Low 0 to 3/4, standard 0 to 15, high 0 to 25 L/min, accuracy 10% |
How to choose: criteria stated in the specification
WHO-UNICEF frames selection around items to specify, not a ranking of products:
- Gas and connector: specify the compatible connector when procuring. DISS connectors are gas-specific, and the cylinder valve must match the regulator inlet (pin index or bullnose).
- Flow device: decide whether a basic regulator, or one with a Thorpe or Bourdon flowmeter, fits the use. Thorpe tubes need a separate pressure-reducing valve and a vertical position; Bourdon gauges can be used at any angle.
- Flow range: pick the low, standard or high range tier from the table above.
- Standard compliance: the specification refers to ISO 10524 for pressure regulators used with medical gases.
- Warranty: WHO-UNICEF recommends a 3-year warranty on regulators and valves, and at least 2 years.
- Total cost: the pressure-reducing valve is a required accessory for some set-ups and belongs in the cost of the whole system.
Safe use and handling basics
- Protect the cylinder and all other fittings from contamination by oil and grease.
- Never use lubricants, because they are flammable.
- Keep a Thorpe-tube flowmeter vertical. Read the float at the centre when it is a ball, and from the top when it is a bobbin.
- Disconnect the device before cleaning, and clean it according to the manufacturer’s instructions and your infection prevention and control protocol.
- Use only connectors made for oxygen; the pin index and DISS systems exist so the wrong gas cannot be connected.
For cylinder handling, storage and identification, see compressed gas cylinder safety and compressed gas cylinder colour codes.
Common mistakes
- Lubricating a fitting. The specification warns against any lubricant on oxygen equipment.
- Using a Thorpe tube off-vertical. It must be vertical to read correctly.
- Assuming a dial or click-type device measures flow. It regulates flow but does not measure it, and is accurate only at its rated 345 kPa.
- Buying a Thorpe flowmeter without a pressure-reducing valve. It requires one.
- Not specifying the connector. DISS threads differ for each gas, so state the compatible connector when procuring.
Frequently asked questions
What does an oxygen regulator do?
It reduces the high pressure inside an oxygen cylinder to a low outlet pressure (345 kPa, or 50 psi, in the WHO-UNICEF specification), and some models also control or show the flow.
Is a regulator the same as a flowmeter?
No. A regulator controls pressure; a flowmeter sets or shows flow. A Thorpe-tube flowmeter needs a separate pressure-reducing valve, while Bourdon and dial types integrate one. Some regulators come with a flowmeter attached.
What standard covers oxygen regulators?
BS EN ISO 10524-1:2019, published 28 February 2019, covers design, construction, type testing and marking requirements for pressure regulators for medical gases, including those with integral flow-metering devices.
Why can’t a regulator from another gas be used on oxygen?
Connections are gas-specific. The pin index arrangement is unique for each gas, and DISS connectors have a unique diameter per gas, which prevents the wrong gas being connected.
Where do regulators fit with other oxygen supplies?
The regulator feeds a delivery device such as a nasal cannula; see the nasal cannula flow rate and sizing guide. Oxygen masks are listed in the CPAP and oxygen masks category.
Sources
- WHO and UNICEF, Technical specifications and guidance for oxygen therapy devices, WHO Medical device technical series, 14 January 2019, ISBN 9789241516914: who.int/publications/i/item/9789241516914 (checked 29 October 2026).
- BSI, BS EN ISO 10524-1:2019, Pressure regulators for use with medical gases. Pressure regulators and pressure regulators with flow-metering devices: BSI Knowledge listing (checked 29 October 2026).
