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Control Panel in an Acidic Environment

CSkinner
We are looking at installing a 316L Control panel within an environment where Sulfuric Acid is handled extensively.


Where can I look to understand what special requirements are needed for this environment?

I understand that Hydrogen Sulphide turns Copper into Copper Sulphate - which has a significantly lower conductivity level;

To mitigate/slow down that reaction, tinning exposed copper is usually practiced - but I don't know what is required for Tri-rated cabling and components such as Contactors etc.


The control panel is only going to be open for maintenance purposes, so the internals aren't going to be subjected to much vapour, and any spills would be on the outside of the panel.

I have a feeling that as the components are protected by the panel, to IP54 minimum, that the corrosion would be at a slow enough rate to reasonably not have to worry about it when thinking about the life expectancy of the panel - but any advise and references would be appreciated.


Thanks
  • 0
    Make the unit as airtight as possible. Consider remotely siting contactors and power circuits in a clean area, such that the control panel only contains ELV relays, pilot lamps, and switches.

    Select sealed components as far as possible.


    In extreme cases consider very slightly pressurising the control panel with clean compressed air obtained from an existing air system.
  • 0
    Thanks for the response.


    If mounting the contactors and power circuits in a clean area needs to be avoided (by request) would mounting them in a smaller Stainless Steel box, within the control panel, be sufficient? (Effectively making them sealed components)


    Assuming the construction of the smaller box is air tight, and access is maintained via glands?

    Would I need to go with ATEX glands for this, too?
  • 0
    Before getting too worried, how is the rest of the building done? - are there special door handles, hinges etc  or is it normal mild steel.

    Sealed enclosures that are positive pressure are very good but may well be not needed - for example If folk are working in without breathing apparatus, then it should be well ventilated and that is really the key.

    (" The solution to pollution is dilution" as per the fire brigade... ) 

    The problem is enclosed spaces where vapours build up. The old ships battery locker type set up was very bad, as there was no where for the vapour to go, and anything left about got corroded very quickly.

    Not opening the panel is good, so long as it is not opened and then shut when the vapour concentration is high..


    Mild steel will rust like the seaside in an acidic atmosphere, so making sure things like trunking are well painted at all cuts and joints and so forth, and delicate things are inside plastic enclosures, or ideally not there at all, but some way off in an office or similar.

    Plastic conduit is better than steel !!


    Mike.

  • 0
    Very useful, thanks. I hadn't considered plastic, as I thought it would melt where as Stainless Steel would show to be more resistant; guess it depends on the plastic!


    The customer has 316L Stainless Steel everywhere, and the employees aren't wearing breathing apparatus; just appropriate gloves.

    My impression is that it isn't an inherently dangerous place to be, like ATEX; I was just worried about the panel being in that environment 24/7 for years.


    In regards to tri-rated cabling, are there any special precautions I should be taking? I've asked our supplier about "tinned" tri-rated and they only do it by the kilometer; but I don't know if I need it or if I'm being overly cautious.

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