Air / H2S Filter for PLC RACK/ Cards

Dear All,
I would like to have recommendations on how to filter out the fumes of Hydrogen Sulfide gas in the plc cabinet. The cabinet is attached to the electrical panel for air blower . The inlet air comes from adjacent dewatering room where the H2S gas is coming from. It had cost us a lot of damage in grounding and frequent plc card breakdown.
The cabinet is isolated by a glass/ aluminum enclosure but the duct is interconnected to the dewatering room where our fan for power supply cools the board.
Any solution is kindly appreciated

regards,

Fidel

dry compressed air

Fidel hi,
First seal the cabinet as best as possible.Increase the pressure in the cabinet by using DRY compressed air.

This should keep any H2S gas out of the cabinet.

In the cable duct: Use some of the self-expanding foam that is used to seal the gap between windows and the bricks, and doors and the walls.
If you need to lay additional cables it will be easy to drill thru the foam.

dear Jesper and Stevez,
All the good tips are ok and will start on Monday to work out on this one ......
thanks for your support.....

This is a tough problem. Steve's solution is a good one if you have a source of clean compressed air. I've had some success with the corrosion inhibiting packs available from Hoffman as one of their enclosure accessories. In extreme cases I've also used the spray cans of conformal coating from 3-M and sprayed the bejeezus out of the panel - terminal blocks, cards, basically any exposed copper. You can't spray switch and relay contacts, though, and they will eventually degrade.

Make sure you use duct caulk on the conduit entrances. You might also look at explosion proof enclosures.

Tom,
do you have a link to these "corrosion inhibiting packs available from Hoffman" ?

The site is http://www.hoffmanonline.com/

The product is "Corrosion Inhibitors" Part number A-HC110E and similar

Thanks for the link, Tom.

Maybe this stuff could have saved us approx 15000 EUROs in PLCs and operator panels.

The description of this stuff says "Hoffman corrosion inhibitors protect ... Electrical and electronic equipment and controls ...".

Would you say that if it is placed inside a control cabinet, then it will self-deploy over the internals of a PLC for example ?

JesperMP said:

Would you say that if it is placed inside a control cabinet, then it will self-deploy over the internals of a PLC for example ?

Click to expand...

That's the theory. The material evaporates from the foam and re-deposits on metal surfaces.

The stuff works pretty good, but the cartridge must be replaced annually. I've seen it help with H2S, but it won't eliminate the problem. Conformal coating is better, and the two together help a lot. Purged enclosures are probably the best bet.

Dear Jesper And Tom,

One important detail Ive forgot to mention....
The plc panel has an inlet fan with mat filter .. The power supply has three fans each to cool down the card in the CCU and and ECU cabinet separately... My problem is I cannot get a clean air intake and would probably get it with a distance of 30 meters just to avoid the hydrogen Sulfide gas......
If I reverse the direction of the inlet fan to go outside the cabinet. Will it heat up the cabinet plc cards???? And also The air condition unit is beside the panel to cool down the exterior of the cabinet .....

In the meantime, I will surf your suggested corrosion inhibitors....

regards,

Fidel