Need Help with H2S Gas from Ground

What about personnel? H₂S is toxic. Can they be diverted away from the H₂S gas as well?

Among the options:

• Forced ventilation with fresh air from elsewhere
• Relocate the equipment into an H₂S-free area.

H2S is very dangerous. In a high concentration the first breath you inhale just paralyzes you, it is the second breath that actually kills you.

If I were you I would move as soon as possible.

At the very least, you need a reliable vapor barrier. They exist; including for H2S.

http://www.tritonsystems.co.uk/prodi1.php#p5

http://remediation.cetco.com/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=352&Command=Core_Download&PortalId=9&TabId=1384

"Is there any way that we can absorb / divert the H2S gas away from our equipments?"

Knock down the building, excavate and put a cap over it with lines to run the gas off site to a torch to burn this harmful gas off. Build a new building on your improved site.

It maybe cheaper and better for your health if you just moved.

There are ways to deal with that gas. We have sources of it in our sewer systems and diversion/avoidance is not an option.

If you contact "odour control specialists" they will be able to give you insight into means to capture and neutralise the gas.

The solutions are not necessarily cheap for what you described, but safety of staff is the real issue.

H2S is NASTY!!!! If you can smell it, then it is dangerous, but the problem is that if you are exposed, the ability to smell it is masked and you can think you are safe. You should also install gas monitoring equipment on site with alarms for levels that exceed allowable exposure limits and so on. Blah .... Blah ....Blah... (Not condescending, but there's a lot for you to considder.)

We use some absorbtion beds that have organic material (Coconut husk) that is maintained moist so the H2S reacts with that. It's easily replenished. Others use various surface area exposures to neutralise the gas.

Can you seal the room and then create a positive pressure to keep the H2S out. You also should install an H2S monitor with alarms to prevent personal injury as this stuff is lethal. Your air source should be taken from an area that is H2S free and filtered as required to safe guard the equipment. Other options have been mentioned.. This may be most cost effective ( just an assumption)

You can seal & purge the entire room, or only seal & purge the control enclosures.

Following is a link to enclosure purging equipment. They have built-in alarms to warn of pressure loss.

http://www.pepperl-fuchs.com/global/en/classid_1762.htm?view=productgroupoverview

Since H2S damages the control panels and can cause harm to personnel, the most obvious way of protecting both is to put a pressurized HVAC system such that the air into the building has a positive pressure and is taken from an area free from H2S.

Prevention is better than chemical neutralization.

You can use an air vent so that the H2S gas will get released out to top.

Have combined air circulation & suction systems of gas.

Pass compressed air into the system to prevent anaerobic conditions.

Possible oxygen / mixed air circulation systems with exhaust.

Possible water proof / resin bonded coatings to corrosion prone components.

We share your pain. Sorry, but most of the suggestions above are impractical. I work in an area of New Zealand that has large Geothermal steam fields. This brings with it different levels of H2S in the atmosphere. I am currently Commissioning a 166 MW geothermal power station using 4.5 Bar steam from a number of wells. We learnt our lesson the hard way in the early eighties with the introduction of micro processor control systems. Within six months the circuit boards started to delaminate. You can spray the boards but you cannot spray the contactors/connectors. You will have noticed that your wires have turned black.

So what can you do about it?

Forced ventilation, HVAC will do nothing except accelerate the corrosion. H2S surrounds you not just from ground leakage.

You need to.

1. Seal the building. How you do that will depend on its construction. Tells us that and we can advise how to do it. For instance if it is breeze block or brick, that will need to be sealed as H2S can permeate through that material.

2. Seal all cables passing through the building. The expanded foam is good for that. If you add an extra cable make sure you seal the new hole immediately.

3. If possible add an air lock into the room.

4. Install Purafil filters. Google it. These will remove or significantly reduce your background H2S. This is a must.

As our H2S level can be high we also have to tin all of our cable connectors. Brass and copper fittings cannot be used as they corrode

Hope the above is of help. We can share our Geothermal spec with you that covers all of the tasks that we need to do combat this problem.

Finally take the advise of one of the above comments, ensure you have detectors in the control room. Also on site. It is heavier than air, collects in trenches and depressions.

Thanks for all your comments. I have never expected that this issue is so common that most of you already have a proven method to circumvent this issue. Yes, we believe our control room is built on top of a previous dumping ground, and the source of H2S is actually from the garbage bio-degradation.