OT: Sealing Conduits

I need to seal some condiuts in varios cabinets because it is cassing extra heat load to be inroduced into the control cabinets and the AC units are having a hard time keeping the drives cool.

I know of 3 methods to do this the first is silicone and it is the cheapest solution but i don't know the down sides to it.

The second is expanding spray foam but it is messy,gets hard and i have heard that it can damage some types of insulation. Is this true?

The third option is duct seal http://www.rainbowtech.net/products/view.php?cn=4035 which is the most expensive but it is made for that purpose but i don't know how well it works.

Could i get some experienced opinions on this please?

Someone here likes the expanding foam. I hate it. It tends to go much farther than necessary into the pipes making wire replacement next to impossible without yanking out all the conductors. I have no proof that it damages insulation, but it would not surprise me. Sidenote: I once "glued" down a small backyard storage building with that "Great Stuff" and it withstood 60mph winds. I got divorced before I got around to putting in anchors but that building is still there 15 years later. It's great for construction, not so much for wiring in my opinion.

Silicone would probably better.

My favorite is some type of putty I have found in some installations. That stuff was very dark colored but apparently remains flexible (reusable) for years. Just last Sunday I needed to remove some spare wires from a pipe that had not been touched in probably a decade and luckily they used the putty to seal it. It's probably the same stuff as in your link.

I would suspect using anything other than an approved Duct seal would be a code violation no?

Conduit fill rules are in place for two reasons as I understand it. 1 to make sure its physically possible to pull the wires, and 2 to ensure adequate heat dissapation of the conductors. Using insulating foam would seem to contradict #2.

I would go with Duct Seal, as you stated it is designed for that purpoes, works well, and stays pliable for a long time.

Any Electrical Wholesaler should have it. I haven't bought any in a while, but I don't remember it being too expensive.

Stu....

We use duct seal here all the time.
I find that i have to go behind almost all the new guys and add more to the conduits in order to seal around the wires. They don't use enough to get around the wires.

Works great !
It remains soft even after its been in there several months.

regards,
james

allscott said:

Conduit fill rules are in place for two reasons as I understand it. 1 to make sure its physically possible to pull the wires, and 2 to ensure adequate heat dissapation of the conductors. Using insulating foam would seem to contradict #2.

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I am sorry but I have to disagree with you on #2. If that what where the case we wouldn't be able to pour seal offs in a Explosion Proof (XP) area. Look at all those conduits run at you local gas station with seal offs. They are outside in direct sunlight so you have sweater for direct contact with mounting surface. Then you pour it closed

The Plc Kid said:

I need to seal some condiuts in varios cabinets because it is cassing extra heat load to be inroduced into the control cabinets and the AC units are having a hard time keeping the drives cool.

I know of 3 methods to do this the first is silicone and it is the cheapest solution but i don't know the down sides to it.

The second is expanding spray foam but it is messy,gets hard and i have heard that it can damage some types of insulation. Is this true?

The third option is duct seal http://www.rainbowtech.net/products/view.php?cn=4035 which is the most expensive but it is made for that purpose but i don't know how well it works.

Could i get some experienced opinions on this please?

Click to expand...

Kid

I believe NEC requires some kind of seal where conduits go from one temperature extreme (?) to another. I think I would check with a refrigeration outfit and see what they do in freezers. You may also check with electrical supply and see if they have a fitting. I would not put any kind of goop inside the conduit - if you do Murphy will ensure you will have to repull that wire. I think the farthest I would go with this is fiberglass insulation jammed in the conduit for say just a couple inches. This should reduce flow of hot air BUT will do nothing for conductive heat transfer ie from conduit to cabinet metal.

I think I would also be checking my conduit to ensure wire runs are not overheating ie overloaded wire run. I have seen a couple that got quite warm.

Dan Bentler

OkiePC said:

My favorite is some type of putty I have found in some installations. That stuff was very dark colored but apparently remains flexible (reusable) for years. Just last Sunday I needed to remove some spare wires from a pipe that had not been touched in probably a decade and luckily they used the putty to seal it. It's probably the same stuff as in your link.

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This description from Okie sounds very much like Pyrotanix cold seal, I just wish it was still availabe as it was a good flexible sealer

I have seen blue tack used to do a similar job

Hi
I have used this in the past

http://www.cooperindustries.com/con...conduitsealinghubandtscepoxysealingcompo.html

Don't use plain silicone. It doesn't play well with electronics.

And off the shelf spray foam is just messy and not made for the job.

I have to agree with the duct seal. I have used it quite a bit and it does well and is made for the job.

Edit: I picked up the last I used at one of the big box stores, Lowes or Home Depot. I was surprised that they carried it.

In my experience duct caulk (they call it duct seal putty in the link you included in post #1) is a good solution. Works well, not to tough to remove, not expenseive, and not difficult to apply.

Duct seal is what h have always called it. It's great I was in a lift station once and needed to pull a another wire. When I removed it water came out the pipes. It's good stuff.

icky812 said:

Don't use plain silicone. It doesn't play well with electronics.

And off the shelf spray foam is just messy and not made for the job.

I have to agree with the duct seal. I have used it quite a bit and it does well and is made for the job.

Edit: I picked up the last I used at one of the big box stores, Lowes or Home Depot. I was surprised that they carried it.

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Icky can you elaborate? Does not pl;ay well with electronics?

Kid

I believe they are referring to the RTV type sealants that use acetic acid ie smell like vinegar. From little I have read acetic acid is not a good thing to use around solid state components. Sorta makes sense. How much acetic acid vapors recondense on solid state or gets dispersed in the airspace I have no idea.

Dan Bentler

What Dan said. Acetic Acid vapor can/will eat electronic traces.

They make RTV silicone for electronics that doesn't have Acetic Acid in it that is friendly to copper, but the stuff you buy at the home center can create issues.