Dilution Ventilation

There are two basic types of ventilation equipment: dilution ventilation and exhaust ventilation.

Dilution ventilation lowers the concentration of atmospheric hazards by bringing in fresh air. This is a more basic form of ventilation and is useful only if all of the following circumstances are met:

• There is only a small and constant amount of hazardous gas, dust, and vapor.
• The air movement created by the ventilation is enough to keep the concentration acceptably low. We will discuss acceptable levels shortly.
• The gas, vapor, or dust is not very toxic or flammable.
• The gas, vapor, or dust will not harm the nearby surroundings or other people (for example, this type of ventilation should not be used with corrosive gas, because the gas could still damage equipment in the surrounding area or hurt coworkers near the exhaust).

Note that depending on what type of hazardous gas you are working around, certain ventilation systems might make things more dangerous. Make sure that your ventilation system is approved for use around the atmospheric hazards you are working with.

To learn more about Confined Spaces visit our Construction Confined Spaces Online Training web page.