# Dielectric Unions on compressed air line?



## SuperDave90 (Apr 2, 2010)

Hey Guys
Are dielectric unions needed on a compressed air piping system that goes from black pipe to copper? By code?

TIA


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## plumbpro (Mar 10, 2010)

First post an intro


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## plumbrob (Mar 21, 2010)

What does your code book say?


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## ChrisConnor (Dec 31, 2009)

SuperDave90 said:


> Hey Guys
> Are dielectric unions needed on a compressed air piping system that goes from black pipe to copper? By code?
> 
> TIA


:lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol::lol:


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## WilkesBarreRoot (Feb 24, 2010)

*Common sense not always*

I am going to only put in my opinion here, not code per your question...

Dialectric is to stop the chemical reaction between copper and black... so it is probably not in your code book persay..... but you can bet the inspector will deem it unsavory....
can you use a threaded compression valve as well....dont know..

for the price of copper i would go black all the way....
once you go black, you never come back...is the saying


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## Plasticman (Oct 14, 2008)

WilkesBarreRoot said:


> I am going to only put in my opinion here, not code per your question...
> 
> Dialectric is to stop the chemical reaction between copper and black... so it is probably not in your code book persay..... but you can bet the inspector will deem it unsavory....
> can you use a threaded compression valve as well....dont know..
> ...


That right there is funny. I don't care who you are!
My sister, is covered with moles. :laughing:


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## Redwood (Sep 8, 2008)

Plasticman said:


> That right there is funny. I don't care who you are!
> My sister, is covered with moles. :laughing:


Gas she got cabbage in her pants too?:laughing:


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## SPH (Nov 4, 2008)

BC Code 2006 - 7.3.3.6. 1) Adaptors, connectors, or mechanical joints used to join dissimilar materials shall be designed to accommodate the required transition.


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## njoy plumbing (May 19, 2009)

SuperDave90 said:


> Hey Guys
> Are dielectric unions needed on a compressed air piping system that goes from black pipe to copper? By code?
> 
> TIA


Use whatever is in your van. Doesn't matter. code 1.2.3.4DIYS MANUAL:thumbsup:
Oh yeah, and don't forget to silicone it!!


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## RealLivePlumber (Jun 22, 2008)

^^^^:thumbsup:No, use putty


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## breid1903 (Feb 8, 2009)

no use epoxy. breid...............:rockon:


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## RealLivePlumber (Jun 22, 2008)

So, I've got a real situation. I don't know how I get myself into these things. 

I have a 20 hp Kohler gas engine, (I know, I know) in a Miller Bobcat 250 welder/generator. The oil drain is on the side of the aluminum engine block. There is a piece of steel (I assume) 1/4" ips pipe, from the factory, with a plastic 1/4 turn (typical Kohler junk) cap on it. But it is still too difficult to access, to change the oil. So, I added a brass 90, then a piece of brass pipe. But, I only had a galvanized cap. (trashed the plastic p.o.s)

Where to put the dielectric union?

:laughing::laughing::laughing:


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## DZ plumb (May 1, 2010)

You don't need a dielectric union for compressed air. Dielectric unions are used in water situation where electrolysis can occur. Although you can get some condensation in compressed air lines it is not enough to cause electrolysis.

For example on a cast iron tapped santee for a urinal you can thread in a copper mip and a sweat ring, water is flowing through but not constantly full of water.


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## highpoint (Mar 3, 2009)

u need a catalyst for electrolysis to occur as it is a chemical reaction.
air is not a catalyst.


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## Yongbae (Feb 22, 2011)

When making a connection using a dialectic fitting, why take the risk of having it leak on you? First you pack the connection with putty(use ample), seal it with silicone(not the tub and tile chalking), then use epoxy on fitting and pipe. This will most certainly guarantee a no leak connection, and your local inspector will appreciate that you took that extra step of quality.


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## plumber666 (Sep 19, 2010)

Yongbae said:


> When making a connection using a dialectic fitting, why take the risk of having it leak on you? First you pack the connection with putty(use ample), seal it with silicone(not the tub and tile chalking), then use epoxy on fitting and pipe. This will most certainly guarantee a no leak connection, and your local inspector will appreciate that you took that extra step of quality.


Somebody need a dyslexic onion?


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## Airgap (Dec 18, 2008)

yongbae said:


> when making a connection using a dialectic fitting, why take the risk of having it leak on you? First you pack the connection with putty(use ample), seal it with silicone(not the tub and tile chalking), then use epoxy on fitting and pipe. This will most certainly guarantee a no leak connection, and your local inspector will appreciate that you took that extra step of quality.


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## U666A (Dec 11, 2010)

I can't believe on a forum OS supposed "professionals", you all missed the most obvious question...

Is it potable compressed air?!?

Duh!


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## Yongbae (Feb 22, 2011)

plumber666 said:


> Somebody need a dyslexic onion?


I spellcheck fail alot 



Airgap said:


> View attachment 9115


">


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## Yellow Badger (Jan 12, 2011)

I prefer putty then silicone


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## RealLivePlumber (Jun 22, 2008)

Oh my God. here we go again........................


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