What Fitting to Use on a Faucet?

[agentar9]

I installed 2 bathroom faucets. The connections for the hot and cold water supply on the faucet are female 1/2 inch NPT. I bought a threaded male coupler/nipple to attach the water supply lines. I use teflon thread when I installed them. They both have a very very slow leak on both faucets on the end where the nipple connects to the female NPT on the faucet body. They don't leak where the nipple connects to the water supply hose. Have I used the wrong fitting? What is the name of the fitting that should connect to the female NPT? The one I used was a straight brass male piece that is entirely threaded. It was not the fitting that has the sort of rounded end, (flare?).

Pardon my terms if there are not correct.

Here is the link to the diagram and tech specs of the faucet:
http://www.cifialusa.com/prod_techspecs/221.156.XXX.pdf

Thanks for your help!

 

[phishfood]

If the faucet actually does have true 1/2" female pipe thread, than the water seal is created when the tapered male and tapered female threads tighten against each other.

Are you sure that you got the assembly tight enough?

 

[agentar9]

thanks Phishfood

I think I got them tight enough, but maybe not...When I first tested the connections it was leaking faster, but slowed up as I tightened, so now it is very very slow. Is it possible to overtightened or break these things??

I can't remember what the package said the fitting was named, I just got the one that wasn't for gas. Are there different types even though they look similar? You mentioned tapered. Is that an MNPT?

 

[phishfood]

MNPT= Male National Pipe Thread

FNPT= Female National Pipe Thread

Both are tapered to the same degree, so that they will seal against each other.

If a threaded fitting leaks, I never try to tighten it up. I take it back apart, reapply whatever thread sealant I am using for that application, and reassemble. I like to use a few wraps of tape, than paste dope on top of that. Tighten securely, but it is not necessary to try to break things. Remove the areator before turning the faucet on for the first time, to blow out any stray dope. run for a few seconds, than reinstall the areator.

 

[agentar9]

OK, I will take it apart and try again with tape and dope. I just thought it was odd that both hot and cold leaked in the same place on both faucets.

Thanks!