Control Cabinet Cleaning

[jrannis]

This might be a good question for our plant guys.
I have a customer with a Heidelberg press.
The control cabinet is propped open and has a 30" fan blowing directly inside of the open door.
Needless to say, the cabinet now has a thick layer of dust all over the boards and relays.
My job will be to clean the interior of this panel which is the size of a household refrigerator.
It has an interior door with 20 or more plug-in boards. The door swings out of the way to reveal a wall of several different types of relays.
My initial plan of attack is to vacuum out the interior to remove as much of the black dust as possible.
Question:
Are there any specific magic potions sued to clean circuit boards?
Should I just surface clean this time around?
I have about 10 hours or outage time to complete the cleaning.
Any and all comments would be appreciated.
Thanks,
John

 

[AlexB]

Cabinet Cleaning

Cabinet Cleaning

The areas where I have worked, we have found it best to use a vacuum and paint brush on the cabinet inside. If time allows use air, low pressure and blow each board and areas that a brush cannot reach without causing problems. While using air try to use vac. to remove dirt to keep it from settling in the cabinet. BECAREFUL: we had a Lock Out SOP that removed power from a drive cabinet for this type of cleaning. The SOP only stated to open the 480vac breaker in the of the cabinet not the incoming power. A "new" person was given the task on a Shutdown to clean the drive. The person had dirt in the air and during cleaning got the paint brush up into the 480vac breaker at the top where the 480 was. There was a short across both legs and with the dust in the area it blew up. The person was burned very bad and did not return to work for a year. The inside of the drive cabinet looked as if a bomb went off. The SOP for drive cabinet cleaning was changed to state to shut power off at "breaker that feeds cabinet and check with meter at the top of the 480 breaker inside the cabinet before starting work".

 

[petersonra]

I would use a vacuum to clean up as much of the dust as possible first.

Then pull out the cards and dust them with compressed air. A paint brush with soft bristles as suggested by another poster is a good idea too.

We have successfully cleaned grease and other crap off things like this once with a pressure washer at the low pressure setting and simple green. It was kind of a crap shoot, but the stuff we got in was full of this green slime (water based coolant) so we took everything out of the cabinets and washed them off. We dried them with compressed air and/or by dipping the circuit boards in IPA.

Everything but a couple items came out ok.

I would not be surprised if you managed to damage a component here and there during the cleaning process. make sure you have spares available just in case.

 

[brian john]

DRY paint brush and good vacuum, then possibly a blower AS NOTED above. Then CLOSE the door checking all seals and filter the input air. keep spare filters on hand.

 

[wishmaster68]

There is a cleaner call Lectraclean, it dries pretty fast. Might take a look to see if is safe on pc boards. We use it in MCC gear.

 

[jrannis]

Much thanks guys,
I like the idea of bringing in a soft paint brush. :smile:
They will be installing a new filter rack on the exterior doors.
We will for sure lock out the whole panel. Thanks for the heads up.
Interesting story about the dust bomb.

 

[jim dungar]

Interesting story about the dust bomb.

This is one reason that arc flash PPE is required whenever voltage is present in the cabinet, even if the main disconnect is "Off".

And, of course, you know not to use the 'plant' air for blowing things off, don't you?

 

[zbang]

I wouldn't use compressed air on the boards unless you really know that they don't mind static charges. The procedure we used in a steel mill was to pull a board, set it on a grounded anti-static mat, and vacuum while using a bristle brush (not plastic) to loosen the crud. We also used an anti-static vacuum, with a very narrow nozzle. If there is caked-on crud, simple-green and distilled water rinse should do it. Be careful if the boards are conformal-coated, since you don't want to wash that off. Vacuum the backplane, blowing it will just drive crud farther into the connectors.

 

[kc8dxx]

Vacuum the dust. Blowing it around will just ... give it some time to decide where in the cabinet it want's to try out next. ESD matters.

Then fix the root problem. Hopefully that's on somebody's list. Cabinet door should be closed with adequate ventilation means provided.