Dr. Ardevan Bakhtari, CEO of Scentroid

We are frequently asked about the difference between a Flux chamber (or Flux hood) sampling and a Wind tunnel or (Lindvall chamber) and how to choose between them.

The Difference Between a Wind Tunnel Vs Flux Chamber:

The Flux chamber is designed to simulate calm conditions and natural odour or pollutant emissions from a liquid or solid surface. The stainless-steel chamber protects the surface from ambient wind and clean air or nitrogen is pushed into the chamber to gently “sweep” the odours from the surface. Samples are pulled from the chamber using a vacuum chamber (lung sampler).

If you would like more information on our Flux Chamber click here.

A wind tunnel is used to simulate emission when the surface is subjected to steady “laminar” wind conditions. The chamber is designed to direct air generated by a fan over the surface and out the other side where it can be sampled. The air is cleaned using activated charcoal to ensure ambient pollutants do not contaminate the sample.

If you would like more information on our wind tunnel, click here.

Numerous studies have been conducted on the difference in emission rate obtained between the two sampling methods. Overall, the following conclusions have been made:

• If the wind tunnel has low wind speed (below 0.2 m/s) the values are nearly identical.
• For wind speeds more than 0.2 m/s the emission rate obtained by will be reduced.

Selecting the right sampler

If the site is subjected to continuous and steady wind conditions above 0.2 m/s a wind tunnel should be used. However, for all other conditions including sporadic or turbulent wind conditions, a flux chamber provides a better estimation. A flux chamber is much simpler and more compact therefore it is easier to use when conditions permit.

As quoted from Scientist Miroslaw Syzlak-Szydlowski, “By increasing the wind speed above [certain] values, there were significantly different results between those methods. In each of the cases, the odor concentration values from the samples taken using the [flux/static] chamber were higher than those obtained in samples taken by [wind tunnel/Lindvall] chamber.”

Works cited:

Mirosław Szyłak-Szydłowski (2017) Validation of odor concentration from mechanical-biological treatment piles using static chamber and wind tunnel with different windspeed values, Journal of the Air & Waste Management Association, 67:9, 1046-1054, DOI: 10.1080/10962247.2017.1338632

Wind Tunnel Vs Flux Chamber Study can be found here: https://doi.org/10.1080/10962247.2017.1338632