Enclosure humidity and corrosion

micky

Lifetime Supporting Member
micky
Join Date
Aug 2003
Location
DeRidder, La
Posts
83
I have an application where a PLC/HMI is mounted in a pool room, lots of humidity not to mention the ongoing corrosion from a prior chlorine leak. The PLC is a S7-1200 mounted in a Nema 12 enclosure with a Siemens KTP600 display mounted on the door. I am having problems with moisture and corrosion causing the touchscreen to fail or PLC faults. I am looking for ways to try to keep these problems at bay. No instrument air access for a purge system, enclosure is to small for an A/C. Can't mount it outside of the building without someone vandalizing it. Right now my only idea is new components in a fiberglass Nema 4X enclosure and small heater/thermostat and moving it further away from point of most moisture. I am thinking maybe the fiberglass enclosure and heater as opposed to the metal enclosure on brick wall may help keeping the interior from sweating.

Anybody have any other ideas?
 
You could also try a double door, so that your HMI is not directly exposed.
 
Put in a bag of silicagel, when no moisture no corrosion.
and tell the owner to renew every 3 months.
put in a moisturesticker.
 
I would use a nema 4x.

Look up the nema ratings to see which one is washdown. that will give you your best protection.

Look in a chemical reaction chart to see if the chemicals in your application will react with the enclosure you use.
I haven't used on in a long time, but Hoffman used to have one in their catalogue.

regards,
james
 
+1 for the VCI Emitters.

We use the ones that look like a tiny piece of sponge with double sided tape on the back, they just stick right to the inside of the control panel.

We have cabinets that are 20+ years old, on the outside they look like He!!, but on the inside they still look almost new.

The few cabinets that did not get these look like He!! inside and out.

BCS
 
Awesome thanks for the suggestion of the corrosion inhibitors, had totally forgotten that those were available. I had also planned on mounting the HMI on a swing out panel and just putting a window kit in the door.
 
A very large part of my business is swimming pools. I use standard Eldon enclosures from Europe - IP66 or IP54 - and also use a Cosmotec fan and filter for air circulation also IP54. Nothing special. I use Omron PLCs and screens and have so far never had an issue. The main thing is all the plant rooms here have to be ventilated - and nothing will get you out of trouble if there is a chlorine spill on your gear.
 
I know Siemens offers a version of the 1200 (SIPLUS) that has an extended temperature range and a conformal coating, which is supposed to protect the circuit boards against condensation, chemicals, etc. I'm sure it costs a pretty penny, though.

I've never needed chemical resistance, so I don't have any experience with these. Is it marketing fluff, or are conformal coatings effective?
 
BobB said:
The main thing is all the plant rooms here have to be ventilated - and nothing will get you out of trouble if there is a chlorine spill on your gear.
Click to expand...

The room is ventilated but they had a chlorinator leaking for a couple months before they realized it. The room is only about 20x20 but I'm hoping if I mount it further away from the pumps and chlorinator it'll help a little. It'll also be closer to the fresh air intake on the building.
 

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