Life Expectancy - USP-156-B10 & UIS-WCB1

[Joseph_F]

Hello, all!

I am currently performing preventative maintenance on a system running in a caustic environment. The solution is being driven by a USP-156-B10 Built-in HMI + PLC. I have noticed that, after a certain point, typically within a 3-5 year range, Unitronics brand panels used in such environments experience slower processing times / fault more frequently. My coworker and I believe this is due to the controller's close proximity to the environment when the panel door is opened, allowing the caustic air to corrode the system. 

On another system in a similar environment utilizing the UIS-WCB1, the screen lasted for about 4 years before going bad. Is this the life expectancy of such built-in style panels? Is this a result of being in a gaseous / caustic environment? If so, what are some steps that could be taken to remedy this? Thanks!

[Joe Tauser]

2 hours ago, Joseph_F said:

My coworker and I believe this is due to the controller's close proximity to the environment when the panel door is opened

You're probably right on that.  Are other exposed metal parts (typically terminals or lugs) showing signs of corrosion?

 

2 hours ago, Joseph_F said:

Unitronics brand panels used in such environments

That sounds kind of specific to Unitronics.  Does the customer have PanelViews or other HMIs that do not have the failure mode?  If this is a Unitronics problem, we need to bring this up with them.

Either way, you have three choices:

1.  Remove the controls from the environment by re-locating the panels

2.  Remove the environment from the controls by installing an air purge system in the panel to push the gas out

3.  Accept that environment tears up your controls and keep spares loaded with the program handy.

 

Joe T.

[Joseph_F]

2 hours ago, Joe Tauser said:

Does the customer have PanelViews or other HMIs that do not have the failure mode?

For clients who have experienced degradation of their screens (and for recent clientele), we have used Weintek screens with a VNC passthrough, instead of using Unitronics screens - both as the panel screens, and as VNC remote viewers located in different locations across the facility.

 

3 hours ago, Joe Tauser said:

1.  Remove the controls from the environment by re-locating the panels

2.  Remove the environment from the controls by installing an air purge system in the panel to push the gas out

We have also been placing our equipment in "clean rooms" with air purging / ventilation, and this has resulted in fewer maintenance calls related to screen malfunction.

 

3 hours ago, Joe Tauser said:

Are other exposed metal parts (typically terminals or lugs) showing signs of corrosion?

I called the clients I had referred to in the original post and asked them this! (Thanks for the idea 😃) However, they told me that they didn't see any corrosion on the outside of the panel / on the terminals. One client has their panel in a cleanroom with ventilation; another has his panel in the same room as the Seperators, but also has clean air pumped in and out of the room.

I'm not sure whether this is an environment or PLC issue at this point - for now, though, we have found success using the Weintek screens. I've noticed that those screens have smaller ventilation on their backs compared to Unitronics screens. This may help in keeping corrosive gasses out of the internal circuitry. I'm not a hardware engineer, though, so this is just an idea.

[Joe Tauser]

I didn't know your background so I didn't want to start brand dropping.  We use Weintek screens as the HMI when we do an Allen Bradley project.

We frequently use VNC server and the webserver aspect of UniStream for remote display.  Using the Weintek VNC client as you describe is an excellent solution.  No programming needed!

 

Joe T.

[Ausman]

FWIW, I had huge trouble with sensors in a large commercial indoor heated swimming pool environment until I started giving all their internals a liberal spray of circuit board lacquer when replacing with new.  I know this doesn't directly relate to displays, but perhaps it's not the displays themselves, it's the pcb they're connecting to.  Were the failed units disassembled and visually inspected?  Would a coat of lacquer over everything have helped?  The sensors in the above were actually built to withstand the conditions, but the rest of the gizmo wasn't.

As for "fresh" air environment, it can be exceedingly difficult to get good air in some locations. I've seen enclosures with fan driven passive heat exchanger systems used in remote "middle of nowhere"gold mine sites, don't know how well they work and you still have the display "open" anyway as that's what it's for, likely allowing gas exchange into the enclosure through miniscule gaps.  At those same gold mine sites repairing aircons "en masse", I also observed the aluminium finning on evaporators was mostly eaten away, leaving just the copper cores there, despite all sorts of scrubber systems in the "clean testing  room" the systems were servicing.  Some places simply do nasty things to electronics...and humans... and clean room air quality is really dictated by how much expense and trouble is warranted and installed. I was happy I wasn't at these sites for too long......

cheers, Aus

[Joseph_F]

17 hours ago, Ausman said:

Were the failed units disassembled and visually inspected?  Would a coat of lacquer over everything have helped?

We usually conformal coat all of our equipment before sending it out. I'll ask my boss if we've ever taken apart a screen that was out of warranty, but most of our work is done remotely, so our customers usually hold on to pieces of equipment if they've gone out of warranty.

[kvlada]

Check your Unitronics front panel for a small opening on the lower side. That's the speaker grill.

It has a sponge dust isolation, but maybe the caustic materials are somehow seeping in through that hole. Might be worth sealing that hole (if you don't need sound) and trying if the problem persists.