Prof James Lee

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Instrument Support Level 3
Instrument Support Level

Instrument Support Level 3

Manufacturer & Model

Airyx ICAD NO2 / NOx / NO Analyser

CEDA Archive Name


Data Products


Insurance Value


Physical Dimensions

40 cm x 60 cm x 80 cm, 30kg


40 cm x 60 cm x 80 cm, 30kg

Daily Facility Charge



Calendar 2:
Airyx ICAD NO2 / NOx / NO Analyser

Airyx ICAD NO2 / NOx / NO Analyser

The ICAD (Iterative CAvity enhanced DOAS, Airyx GmbH) is a high-sensitivity, compact NOx analyser. It makes direct measurements of NO2 concentrations and includes an O3 titration system to measure NO. It offers 200 ppt limits of detection at 2s (down to ~30 ppt at 1800 s) and is lightweight and low power. The instrument can run unattended for extended periods and utilises a built pc for easy remote operation. The instrument also includes a CO2 measurement, helping to support source apportionment exercises. Data is provided as a time series automatically, with options for the postprocessing of the raw spectra to suit the user’s purposes. 

The ICAD is a direct optical measurement of NO2, and the high-grade version utilises a longer absorption cell and increased reflectivity mirrors to improve its sensitivity. NO is measured via conversion to NO2 by O3 titration. The sample passes through the first optical cavity for the NO2 measurement, then through the NO -> NO2 converter, into a second optical cavity for a total NOx measurement, the difference of this with the first cell produces the NO measurement. The spectrometer alternates between the two cavities every 2 seconds and is the limiting factor in the instrument’s time resolution. The instrument regularly performs automatic zeros using scrubbed ambient air to reduce drift. 

Full details along with instrument specifications can be found here on the manufacturer’s specifications.

As the NO2 measurement is based on a direct spectroscopic technique, a regular calibration of the instrument is not required outside of annual checks to the instrument path length. The NO conversion efficiency may be impacted at high NO concentrations, but these can be assessed before instrument deployment if required. 

The instrument requires no additional supplies to operate.

  • Instrument Insurance
    • The instrument must be insured by the user for £60k and cover loss, theft or damage to the instrument: damage that is over and above the general wear and tear. The system has been designed to be rugged and autonomous. Even so, the end-user must respect the fact that the system is a precision optical instrument that must be treated with great care.
  • Public Liability Insurance
    • The AMOF is not liable for any damage or injury arising from the deployment or operation of this instrument when unattended by the IS.
  • Shipping Expenses
    • The user is liable for all costs arising from the shipping of the instrument both to and from deployment.
  • IS T&S
    • The user is responsible for covering the travel and subsistence expenses of the IS while attending the instrument.

The instrument should be located indoors in an air-conditioned space – ideally mounted in a 19” rack. A 1.4” sample line can be connected to the instrument, via the provided in-line filter, and must be located such that no water can enter the sample line.

Manual Handling
  • While the instrument falls within recommended manual handling weight for a solo lift below shoulder height, it is up to the person performing the lift to assess the situation. It may be desirable to have a second person aid with the lift.
  • The instrument should be held from the sides and its front handles, and no weight should be borne by any of the external fittings
Electrical Safety
  • Check the instrument casing and cables are in good condition before powering on the instrument.
  • Attach all cables to the analyser before switching on at the mains. 
  • All equipment will be provided with in-date electrical safety.

When unpacked the instrument has the following physical specification:

  • 13.2 x 43.8 x 61 cm (19” rack width, 3u high)
  • 12 kg
  • 30 W and 12 V, connected to a 110-230 V, 50-60 Hz, type G plug.
Field Data
  • Data can be viewed live over a local network html interface. 
  • This portal provides options to download the data from the instrument, which should be done regularly for backup purposes. Note this data will not have been quality controlled. 
Archive Data