# What maintenance does a medical air plant need?

**What preventive maintenance does a hospital medical air plant need?**

A hospital medical air plant needs planned work on three fronts: compressor service by running hours, upkeep of the filters, desiccant dryers and sterile filters, and testing of the delivered air against the pharmacopoeia limits, which NHS England guidance sets quarterly for medical air compressor plants.

## Compressors

HTM 02-01 (2026), the NHS England guidance, asks for an hours-run counter on the compressor plant control system, and the ULTRAAR SCA control panel has an hour meter for each compressor. The plant is designed so that one machine can be taken out: the ULTRAAR SCA panel lets a compressor be switched to manual mode when it is removed for preventive maintenance, and in automatic mode it alternates the compressors to even out wear. On the oil-free ULTRACECO ESW piston compressor, the datasheet places the first maintenance at 10,000 hours. HTM 02-01 says the oil separators that treat the condensate should be maintained by specialist providers as part of the compressor contract, and that a strip-down which replaces oil-sealing components needs a follow-up oil test.

## Air treatment

HTM 02-01 gives each dryer assembly its own dew-point sensor and test point after the bacteria filter, and raises a plant emergency alarm when dryness rises above −46 °C at atmospheric pressure. A differential pressure gauge signals critical failure rather than servicing needs, so it does not remove the need for regular inspection. HTM 02-01 adds that rising or fluctuating carbon dioxide readings can be an early sign of dryer failure or poor compressor maintenance. In the Ultra Controlo range, the ULTRAMED treatment station has a colour change indicator for desiccant replacement and a low dew point alarm, the ULTRAAR ME has two ULTRAGEST controllers for continuous dew point monitoring, and the ULTRAAR SCA datasheet notes that the element of its sterilisation filter needs periodic sterilisation.

## Receivers, drains and access (HTM 02-01)

- Electrically operated automatic drains on after-coolers, receivers, separators and coalescing filters, with a manual drain on each receiver as a bypass in case of power loss.
- Statutory inspection of the receivers, made possible without interrupting supply by two valved receivers or a bypass arrangement.
- All-round access to the plant, with room to change major components.

## Air quality testing

Medical air is a medicine, and HTM 02-01 confirms its quality by testing. HTM 02-01 sets quarterly quality control testing for medical and surgical air compressor plants, plus testing after new installations, repairs and modifications. It is the responsibility of the Quality Controller (MGPS), and the acceptance limits for medical air include 5 ppm carbon monoxide, 500 ppm carbon dioxide, 67 vpm water vapour and 0.1 mg/m³ oil.

UltraCare is the Ultra Controlo technical support programme: preventive and corrective maintenance, original spare parts and emergency support, 24 hours a day, 7 days a week.

### How often should medical air quality be tested?

In England, HTM 02-01 (2026) sets quarterly quality control testing for medical and surgical air compressor plants, and testing after new installations, repairs and modifications.

### Who carries out medical air quality testing in the UK?

HTM 02-01 makes it the responsibility of the Quality Controller (MGPS), who should not be acting as Authorised Person or Competent Person on the same project.

## Sources

- [NHS England, HTM 02-01 Medical gas pipeline systems, Part A (2026), paras 7.13, 7.43, 7.50, 7.51, 7.56, 7.58, 7.68, 7.72, 7.89, 20.3, 20.4, 20.65 to 20.76, Table 33](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)
- [ULTRAAR SCA datasheet, p. 3 and 4](https://www.ultracontrolo.com/products/ultraar-sca)
- [ULTRACECO ESW datasheet, p. 3](https://www.ultracontrolo.com/products/ultraceco-esw)
- [ULTRAMED datasheet, p. 3](https://www.ultracontrolo.com/products/ultramed)
- [ULTRAAR ME datasheet, p. 2](https://www.ultracontrolo.com/products/ultraar-me)
- [Ultra Controlo, Medical gas answers: UltraCare (Industrial 2026, p. 22)](https://www.ultracontrolo.com/medical-gas-answers)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/what-maintenance-does-a-medical-air-plant-need/