Tank Ventilation

[Matador]

We have a potential hydrogen suflide problem in a couple of tanks and I would like to know if anyone has a formula to determine how much air should be exhausted from each tank.

The tanks in question have covers but they are vented inside a building. I would like to collect the gas off both tanks using a centifugal fan and discharge it outside the building.

During shutdowns when the tanks are empty extra ventilation equipment would be brought in to get a sufficient number of air changes until the tests indicate it is safe to go inside. Any ideas on how many CFM I need for each tank?

The tanks in question are 40 ft long X 20 ft wide and contain about 20 ft liquid?

Any ideas?

 

[ChasBean1]

Matador, my guess would be just about any air volume. Let's say 150 cfm. You need a makeup air pathway, though (don't just hard duct to the vent - there should be another hole to allow air removal). Make sure your fan materials are appropriate for this type of gas and there are no additional hazards... keep the discharge well away from any intakes. I don't know if there are extra rules for this, though. Why not just run the vent outside?