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Looking for ideas on Electrical Enclosures

Looking for ideas on Electrical Enclosures

Looking for ideas on Electrical Enclosures

(OP)
Hello Everyone,

We have an Electrical enclosure that is located in a very silica dusty area. The enclosure is under positive pressure, but for some reason,we are still having dust accumulation. Any ideas on what might be going on?

Regards,
Mr T
Reliability Engineer

RE: Looking for ideas on Electrical Enclosures

the supply air for the positive pressure isn't adequately filtered?

Dust intrusion while the door is open for servicing, but, of course, 'that never happens'.

RE: Looking for ideas on Electrical Enclosures

(OP)
No Sir, the supply air is not even filtered at all. Also I did observed when I did the initial inspection, that the door was not completely closed.

RE: Looking for ideas on Electrical Enclosures

Is it a box rated for full seal (NEMA 4)?
We used to filer and dry purge air (particle filter, charcoal filter, desiccant all in line).
And our sealed boxes used a filter on the outlet vent valve also.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Looking for ideas on Electrical Enclosures

So do the vents only release at a specific pressure or are they open?
Our boxes were interlocked, if they didn't pressurize (door ajar) an alarm went off.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Looking for ideas on Electrical Enclosures

(OP)
The vents are always open. The air that is being fed into the enclosure goes out through the vent. I do like the idea of an interlocking system that will alert us if the door is open. Thank you Ed

RE: Looking for ideas on Electrical Enclosures

A low pressure differential pressure switch will tell you when any part of the sealing system is not holding positive pressure, as opposed to a door switch that just informs that the door is open.

There's lots of relatively low cost HVAC low DP switches out there. You'd probably want a filter on the atmosphere low side port.

RE: Looking for ideas on Electrical Enclosures

The vents need to have some restriction to them. We used ones with a lightly weighted flapper and then vented out though an exhaust filter. This provided some back pressure and kept debris out.
The HVAC DP switches work fine for this.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Looking for ideas on Electrical Enclosures

Conduits can also contribute to this...if not properly sealed. The dust could actually be pulled in from a conduit, depending on your intake/exhaust fan. I have seen this more than once.

RE: Looking for ideas on Electrical Enclosures

I wonder if you would be better off w/ an environmental purge system, basically like purge systems used for electrically classified areas (think Z purge or X purge setup). Only in this case, you aren't alarming or interlocking a "power-off" setup. You would have a NEMA 4x enclosure, no vented openings, purge controller and a relief vent. Stuff your conduit openings to your box and you should be good.

Mike

RE: Looking for ideas on Electrical Enclosures

Enclosure alone won't work, check the selection of glands.

RE: Looking for ideas on Electrical Enclosures

(OP)
Thank you for all of your replies. I really appreciate you taking the time to reply. I will take all your advice into consideration.

RE: Looking for ideas on Electrical Enclosures

Electrical boxes (like light switches) can work. Radio Shack is offering project boxes. Small projects fit comfortably into the Altoids tin.

RE: Looking for ideas on Electrical Enclosures

What? You still have a radio shack? Most of us don't have any radio shacks any more.

RE: Looking for ideas on Electrical Enclosures

I don't see many electronics stores here. Have to order things, if I want them.

Then again, people don't repair stuff anymore.

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