Matt wrote in
:

On 01/31/2011 10:50 AM, GROVER wrote:
A clerk at my local Ace Hardware told me to use Teflon tape on the
pipe threads but not the compression fittings. I'm trying to stop a
very slow seepage from the couplings and flex hose surrounding a
quarter turn shut off valve serving the cold water faucet to a
bathroom sink.

Is this advice correct?


Yes.

See the Wikipedia article on compression fittings to understand how
they work. Most important thing with those is to be clean and gentle
with them.

Pipe threads are tapered according to the National Pipe Thread (NPT)
standard. See also the Wikipedia article about that. You need teflon
tape or a goopy sealant and a small pipe wrench to stop the leak
there.

http://en.wikipedia.org/wiki/Compression_fittings

Good article. Didn't know this part. Never looked that closely.

"To work properly, the ferrule must be oriented correctly; typically the
ferrule is fitted such that the longest sloping face of the ferrule faces
away from the nut."