Dielectric unions for air piping?

[pancho400cid]

All my air piping is run in 3/4" sweat copper. I'm installing a hose reel I got on sale recently. I need a union to install it. Went to the box stores over the weekend. They did not have a brass union, 1/2" female NPT threads on both ends (or brass NPT threaded unions of any size for that matter).

They did have sweat "dielectric" unions in brass... which I can use, but I thought were more for water lines and coupling dissimilar pipes.

Any reason the dielectric union would not work for air service?

The box stores did have the union I need in galvanized, but I don't really want to mix steel and copper.

Thoughts?

PS - Reel I bought if you care (It was $79.00 last weekend IIRC):

https://www.northerntool.com/shop/tools/product_200658516_200658516

 

[engineer2]

I've been using some for the same reason for years without problems. Couple of things to keep in mind:
They will electrically isolate the line. Not an issue with air lines.
They aren't designed to be assembled-disassembled repeatedly. The plastic bushing will tear.

 

[Ehcrain]

I used these from hd with good luck.

1/2 in. Copper Pressure C x C Union
https://homedepot.app.link/5ui5ckqY2H
SKU# 204620129



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[pancho400cid]

Thanks guys -

I forgot to mention that neither Lowes nor Homey Depot had copper unions that were threaded or sweat on one end and threaded on the other. They had them that were sweat on both ends, which I used a few places when I put the piping in. Those could be forced to work but would take a few extra sweated on fittings on the "free" side of the union.

They had dielectric unions that were sweat on one end and threaded on the other....

 

[sberry]

I take the hose off and install it sometimes, might even install a big ole air connector if I had one laying around and about the best way is to have a threaded hose barb, you can get them in FIP and a hose clamp. If I had a steel union wouldn't let that stop me either.

 

[sberry]

You can get 3/8 mpt to 1/2 barb at the fluid power store, and 3 ft of hose You can get barbs 3/8 to 3/8 and a chunk of 3/8 air hose you can find. Adding a couple 3 more 3/8 to this wont hurt much. About 20 ways to do this including 1/2 hyd hose and a swivel too.

 

[pancho400cid]

Thanks... Also did not mention I'm using a 1/2" id rubber whip line, 3' long, with 1/2" male threads (non-swivel - hence need for union) on both ends to go between the existing tubing and the reel.

Not hearing any "no votes" for the dielectric union so probably will go with that.

 

[kbs2244]

I don't think it is needed.
But I don't think it will hurt anything either.

 

[Firebrick43]

I don't think it is needed.
But I don't think it will hurt anything either.

+1

Not needed but no harm.

Have you looked a supplyhouse.com?

The have every fitting known to man it seems, great service, and it's at my door the next day most of the time. I don't even bother with the box stores anymore except to get pipe. Seems like I was always hitting all three just to get everything I needed and tearing my hair out dealing with the staff.

 

[pancho400cid]

Hey Firebrick43 -

Thanks much for the supplyhouse.com suggestion. My union will be here Friday... I hope...

12 bucks shipped.....