# Second-stage regulator

A second-stage regulator is a pressure regulator that makes a second pressure reduction in a medical gas system, after a first-stage reduction, either within a cylinder manifold, as shown in HTM 02-01 (2026), or, in the Portuguese ACSS ET 03/2006, in the sets that feed each hospital department.

Regulators for medical gas pipelines are covered by ISO 10524-2:2018, which applies to manifold and line pressure regulators; manifold regulators in its scope accept a nominal inlet pressure of up to 300 bar. In its typical automatic [manifold](https://library.ultracontrolo.com/glossary/manifold/), HTM 02-01 (2026) shows each cylinder bank with a first-stage and a second-stage regulator, and it asks for high-pressure regulators to comply with BS EN ISO 10524-2.

In the distribution network, the Portuguese ACSS ET 03/2006 (2024 revision) asks for each hospital department to be fed by at least two second-reduction sets in bypass, installed in visible places as described in ISO 7396-1. The sets should not work at the same time, their alarms should be able to report to the building automation and control system, and, for high-flow oxygen therapy, pressure-reducing sets should sit as close as possible to where the oxygen is made available. Where pressure needs to be reduced on an air system, HTM 02-01 asks for a pressure-reducing station: a duplex set with lead and lag regulators to maintain line pressure, with alarms that monitor both high and low pressure.

Ultra Controlo supplies alarm relay panels for second-stage units and a second-stage vacuum unit for zone-level regulation of medical suction.

## Sources

- [ISO 10524-2:2018, Manifold and line pressure regulators (ISO summary)](https://www.iso.org/standard/66690.html)
- [HTM 02-01 (2026) Part A, Figure 10, paragraphs 3.71 to 3.73, 5.35 and 14.77 (NHS England)](https://www.england.nhs.uk/wp-content/uploads/2016/05/health-technical-memorandum-02-01-medical-gas-pipeline-systems-part-a-design-installation-validation-verification-aug-2026.pdf)
- [ACSS ET 03/2006 v.2024, Gases medicinais (Portugal), sections 6.7, 7.3 and 7.5](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-03_2006_v2024-Gases-medicinais_VF.pdf)
- [Ultra Controlo, Medical gas answers: alarm panels](https://www.ultracontrolo.com/medical-gas-answers)
- [Ultra Controlo, vacuum second stage unit (accessories)](https://www.ultracontrolo.com/accessories/vacuum-2nd-stage-unit)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/second-stage-regulator/