# Should medical air and vacuum plants be on emergency power?

**Should medical air compressors and vacuum pumps be connected to the hospital's essential (emergency) electrical supply?**

HTM 02-01 (2026), the NHS England guidance, says medical air and vacuum plants should be on the essential electrical supply: every component of the medical air supply system should be considered life-critical electrical equipment, and compressors and vacuum pumps should restart automatically, in sequence, when power returns.

The HTM's principle of continuity of supply is to install duplex components as a minimum, keep further means of supply available if the primary and secondary plant fail, keep operating under single fault conditions, and connect the systems to the essential electrical supply.

## Medical air plant

All components of the medical air supply system should be considered life-critical electrical equipment, with the electrical supply provided via an essential electrical source as detailed in HTM 06-01. The operating system should restart automatically when the power supply is reinstated, and the control system should restart the compressors in sequence to avoid overloading the supply; two or more compressors should not start simultaneously when power is applied. The plant control unit should have a separate power supply for each compressor, controlled by a separate subcircuit and a double-pole isolator, and there should be separate power supplies for the duty and standby dryer assemblies. On power failure, the dryer drain and vent valves should fail closed and the inlet and outlet valves should fail open.

## Medical vacuum plant

Medical vacuum plant and equipment should be connected to electrical supplies in line with HTM 06-01 with dual circuits for resilience, and the vacuum supply system should be connected to the essential electrical supply, with pumps restarting in sequence. After a loss of power, the plant should restart automatically to normal operation.

## Alarms, manifolds and PSA plant

The same guidance asks for medical gas alarm panels to take their mains supply from a dedicated circuit that forms part of the essential power supply, for cylinder manifold monitoring, indicating and alarm systems to be on the essential electrical supply, and for all components of a PSA oxygen plant to be connected to it.

## The Portuguese specification

ACSS ET 03/2006 (revised in June 2024) recommends that the means be ensured to keep the medical vacuum system running if the electrical supply is interrupted, and recommends emergency power, for example from a generator, so that on-site oxygen generating units are not affected by a failure of the primary supply.

## Ultra Controlo

For oxygen, the 2022 ULTRAOX datasheet notes that the plant can be connected to a diesel-electric generator.

### Do all the compressors restart at once after a power cut?

No. HTM 02-01 (2026) asks for compressors and vacuum pumps to restart in sequence to avoid overloading the power supply, and for two or more compressors not to start simultaneously when power is applied.

### Which electrical guidance does HTM 02-01 refer to?

HTM 02-01 refers to HTM 06-01 for the essential electrical source of the medical air plant and for the dual-circuit supplies of medical vacuum plant.

## Sources

- [NHS England, HTM 02-01 Medical gas pipeline systems, Part A (2026), Context and background (continuity of supply), paras 5.53, 6.126, 7.78 to 7.81, 7.86, 7.88, 10.4, 10.41, 10.42 and 14.19](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 Especificações técnicas para gases medicinais e aspiração em edifícios hospitalares, sections 4.2.1 and 4.8](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-03_2006_v2024-Gases-medicinais_VF.pdf)
- [ULTRAOX Technical Data Sheet 2022, p. 9](https://www.ultracontrolo.com/products/ultraox)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/must-medical-air-and-vacuum-plants-be-on-emergency-power/