# What does an activated carbon tower do in compressed air?

**What does an activated carbon tower remove from compressed air, and where is it installed?**

An activated carbon tower removes oil vapours and other hydrocarbons from compressed air by adsorption on a bed of activated carbon; the ULTRAK datasheet calls for a coalescing filter upstream and recommends a dust filter downstream to catch carbon residue.

Air treatment works in stages. In the ULTRAMED treatment unit, for example, a coalescing filter first removes water, oil, aerosols and particles, and an activated carbon filter then removes oil vapour and odours. An ULTRAK activated carbon tower is a dedicated stage for oil vapour: flow distributors spread the air evenly through a bed of activated carbon, and the oil vapours and other hydrocarbons are separated by adsorption, a dry separation.

## Where it is installed

- After a coalescing filter: the ULTRAK datasheet says one is required upstream.
- Before a dust filter: a 1 μm dust filter is recommended downstream to intercept any residue from the activated carbon.
- In medical air plants, HTM 02-01 (2026) lists a carbon filter among the typical filters of the dryer system, together with water and oil filters, two desiccant columns, a dust filter and a bacteria filter.

## ULTRAK figures

| Parameter | ULTRAK datasheet value |
|---|---|
| Residual oil vapour content (nominal) | < 0.003 mg/m³ |
| ISO 8573-1 quality class, oils | 0/1 |
| Operating pressure | 16 bar |
| Operating temperature | 1.5 to 45 °C |
| Flow range | 6 to 6,500 Nm³/h |
| Pressure drop, new and dry | 20 mbar (0.29 psi) |

The datasheet gives an ISO 8573-1 class only for oil; the classes for solids and water are left blank.

In Ultra Controlo medical air treatment, the ULTRAMED unit includes a high efficiency activated carbon filter that reduces oil vapour and odours down to 0.003 mg/m³.

### Does an oil-free compressor still need a carbon filter?

HTM 02-01 says oil-free compressors reduce filtration requirements, but its typical medical air dryer system still includes a carbon filter.

### Why is a filter needed after the carbon tower?

The ULTRAK datasheet recommends a 1 μm dust filter downstream to intercept any residue from the activated carbon.

## Sources

- [ULTRAK datasheet, p. 2](https://www.ultracontrolo.com/products/ultrak)
- [ULTRAMED datasheet, p. 3](https://www.ultracontrolo.com/products/ultramed)
- [NHS England, HTM 02-01 Medical gas pipeline systems (2026), Part A, 7.34 and 7.64](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)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/answers/what-does-an-activated-carbon-tower-do/