# Does medical air need continuous quality monitoring?

**Does a medical air plant need continuous monitoring of dew point, CO and other parameters?**

HTM 02-01 (2026) calls for continuous dew point monitoring at the medical air plant, with a sensor on each dryer assembly and an alarm if dryness rises above −46 °C; the other contaminants are checked by quality control testing, quarterly for compressor plants.

Under HTM 02-01 (2026), each dryer assembly has its own dew point sensor and test point after the bacteria filter, so that the dryer can be tested before it comes online and the product can be monitored continuously. The dryer control unit carries hygrometers set to −46 °C atmospheric dew point and changes over automatically to the standby dryer if the duty dryer fails on dryness or pressure.

## Alarms

Dryness above −46 °C at atmospheric pressure is a plant emergency condition in HTM 02-01, as is receiver pressure 50 kPa below the standby cut-in pressure or 50 kPa above the cut-out pressure. Plant fault and emergency conditions are transmitted to the central alarm system, and volt-free contacts allow a building management system to monitor the plant, though it should not control it.

## What is tested periodically

Carbon monoxide, carbon dioxide, sulphur dioxide, oxides of nitrogen, oil, particles and odour are covered by quality control testing against the acceptance criteria in HTM 02-01 Table 34, and the HTM sets quarterly testing for medical and surgical air compressor plants. HTM 02-01 is NHS England guidance: in the United States the rules for medical gas systems are in NFPA 99 (current edition 2027), and elsewhere the national specification applies.

## Monitoring on Ultra Controlo equipment

- ULTRAAR ME has two integrated ULTRAGEST systems that monitor and control the dew point of the air supplied to the network continuously.
- ULTRAMED treatment units change columns according to dew point, have a low dew point indicator alarm, and accept a digital dew point indicator for continuous outlet monitoring, which is not included as standard.
- ULTRAAR SC plants have a 24-hour remote monitoring system available and can connect to a management system or central alarm network.

### Why is carbon dioxide watched in medical air?

HTM 02-01 notes that increasing or fluctuating carbon dioxide readings in air can be an early sign of dryer failure or poor compressor maintenance.

### Can the building management system control the air plant?

No. HTM 02-01 says the BMS should only monitor the plant, not control its functions, changes or isolations.

## Sources

- [NHS England, HTM 02-01 Medical gas pipeline systems (2026), Part A, chapter 7, chapter 20, Table 33 and Table 34](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)
- [NFPA 99, Health Care Facilities Code: current edition page](https://www.nfpa.org/codes-and-standards/nfpa-99-standard-development/99)
- [ULTRAAR ME datasheet, p. 2](https://www.ultracontrolo.com/products/ultraar-me)
- [ULTRAMED datasheet, pp. 2 and 3](https://www.ultracontrolo.com/products/ultramed)
- [ULTRAAR SC datasheet, p. 3](https://www.ultracontrolo.com/products/ultraar-sc)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/does-medical-air-need-continuous-monitoring/