Adequate ventilation safeguards

[dgalenski@glauber.com]

I am trying to research what the requirements are to safeguard a fan that is used to provide "adequate ventilation" to classify an area as CI, D2. I stumble across a lot of information about safeguards that ensure the fan is moving air, but none on approved devices or methods. Does anyone have any input on this subject? Thanks in advance.

 

[petersonra]

I am trying to research what the requirements are to safeguard a fan that is used to provide "adequate ventilation" to classify an area as CI, D2. I stumble across a lot of information about safeguards that ensure the fan is moving air, but none on approved devices or methods. Does anyone have any input on this subject? Thanks in advance.

This would seem to cover it.

Approved. Acceptable to the authority having jurisdiction.

 

[GoldDigger]

This would seem to cover it.

Somewhere along the way someone, possibly a PE, possibly not, will have to look at the volume of air moved per minute by the fan(s), the size of the room, the sources of makeup air and the resulting flow pattern and make a determination that for the likely rate at which flammable material is being introduced the ventilation is enough to keep the concentration to a safe level.
I would then expect some of those calculations to be found in texts and references for HVAC.

For hydrogen, for example, an open roof without any forced air movement will probably be enough. "Adequate ventilation" does not automatically require use of fans.

Beyond that initial design, it comes down to assurances that the system is turned on and working properly when it is needed. You seem to have found discussions of that second part.

 

[don_resqcapt19]

It is my opinion that if you are using forced (mechanical) ventilation of any type to keep an area Class I, Division 2, then there must be some type of alarm and interlock to warn and shut down the power if the ventilation would fail. ( I don't have a code section to back this up)