2001 was an excellent year for smoke tests. The year saw the development of cleanroom ultrapure foggers. With this development came high-quality fog.

That raises the question, “What determines the quality of fog?” The answer in a word, density.

Fog density refers to the amount of liquid converted to fog in a minute. The higher the volume converted, the thicker the fog, and the more pronounced the effect of air. Let's take an example to illustrate fog density:

The CRF2 Clean Room Fogger has a fog density of 57ml/minute.

That means that in every minute, 57ml of water is converted to fog: Fogging devices operate by atomizing de-ionized (DI) water into droplets that are typically 2µm- 4µm wide.

So, what makes dense ultrapure fog suitable for smoke tests? There are three main reasons:

• Details
• Visibility
• Purity

Visibility
Ultrapure fog is both dense and visible. These two properties are vital when studying the effects of airflow on the fog. Fog needs to be thick enough for the impact of airflow to be easily discerned without sacrificing too much visibility.

What does that mean?

Imagine a smoke test where the fog is dense, but not visible. In such a case, you are only able to observe airflow behavior on the fringes of the fog. For the sake of accuracy, however, you need to be able to see air behavior beyond the edges.

Details
Dense fog allows you to observe the slightest of air disturbances in a cleanroom. Ultrapure fog is popular for its density.

Purity
The water used to produce ultrapure fog is pure. This means that after the droplets evaporate, they leave no residue. This is vital. It keeps the cleanroom uncontaminated.

Ultrapure foggers can, therefore, be used in pharmaceutical settings without the risk of corrupting future tests.

That said, density may be the most important metric with which to measure the quality of a fogger, but it's not the only thing that determines efficacy. Two main features determine the suitability of a fogger for your specific needs:

• Fog Volume
• Fogger Operation Time

Fogger Operation Time
Foggers have different operation times. To choose the most appropriate fogger for your needs, ensure that the device can produce the required amount of fog within its operational time.

Fog Volume
Fog volume is a component of fog density. It is the volume of fog released per minute. To illustrate, let’s recall the device we used to explain fog density- the CRF2 Cleanroom Fogger:

The CRF2 has a fog volume of 0.26 cubic meters per minute. It has an operation time of about 50 minutes. That means that it produces about nine cubic feet of dense fog in a single operation.

That said, the volume of your cleanroom determines the volume of the fogger you purchase