# Condensate drain (drain trap)

The US Department of Energy compressed air sourcebook describes traps, sometimes called drains, as the devices that remove moisture from a compressed air system; NHS England guidance, HTM 02-01 (2026), asks for electrically operated automatic drainage traps on the after-coolers, receivers, separators and coalescing filters of medical air plant.

The US Department of Energy compressed air sourcebook (third edition) describes four methods: manual valves, which are too often left open; level-operated mechanical traps, such as float traps; timed solenoid valves, which may not stay open long enough and open even when little or no condensate is present, losing compressed air; and zero air-loss traps with reservoirs, of various types, one of which uses a float or level sensor to operate a valve that keeps the condensate below the high-level point.

HTM 02-01 (2026) asks for receivers to be fitted with electrically operated automatic drains, which it says have been found more reliable, plus a manual drain as a bypass in the event of power loss, and says any discharge from the drainage traps must be piped to a suitable oil separator. For hospital technical air, the Portuguese ACSS ET 08/2010 (V.2025) asks for a reliable automatic drain on each dryer and recommends zero-loss or intelligent drains that open only when condensate is present.

The ULTRAOX oxygen plant includes a water separator with electronic drain in its air treatment, and the customer provides the conditions for collecting or draining the condensate. ULTRATECH has filters fitted with zero-loss drains, and automatic drains with test buttons, and the [ACIH](https://library.ultracontrolo.com/products/acih/) system has a condensate treatment unit that removes the oil so the condensate can go to the sanitary network.

## Sources

- [US Department of Energy, Improving Compressed Air System Performance: A Sourcebook for Industry, third edition, Traps](https://www.energy.gov/sites/prod/files/2016/03/f30/Improving%20Compressed%20Air%20Sourcebook%20version%203.pdf)
- [HTM 02-01 (2026) Part A, paragraphs 7.50, 7.56 and 7.57 (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 08/2010 V.2025, Especificações técnicas para ar comprimido técnico em edifícios hospitalares, section 4.2.6.5](https://www.acss.min-saude.pt/wp-content/uploads/2016/10/ET-08_2010_V.2025_VF.pdf)
- [ULTRAOX Technical Data Sheet 2022, p. 9 and p. 16](https://www.ultracontrolo.com/products/ultraox)
- [ULTRATECH datasheet, p. 2](https://www.ultracontrolo.com/products/ultratech)
- [ACIH datasheet, p. 3](https://www.ultracontrolo.com/products/acih)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/condensate-drain/