How tight should the barb of a compression fitting be?
- Thread starter Amidar
- Start date
Do you mean the threaded end? It needs to be enough to compress the O ring to stop leaks, but compression fittings have a lovely tendency to unwind if there is any twist left in the tube. That's one reason in favour of doing them up tighter.
What torque is reasonable depends on what you're screwing it into. A piece of plexi will fracture at much lower values than a piece of brass, so while I wouldn't go beyond finger tight on plexi (anymore, I broke the top of an ek block a while back), I'll cheerfully go to the limits of what I can sensibly apply with a spanner when screwing into a brass fitting. A radiator is somewhere in between, you're pretty unlikely to pull the threaded insert out, but with enough effort it might happen.
A reasonable rule of thumb is to apply a torque using two fingers only, at the end of the handle close to the nut. Even that will probably break plexi though.
(I don't think plexi should be anywhere near water cooling
)
What torque is reasonable depends on what you're screwing it into. A piece of plexi will fracture at much lower values than a piece of brass, so while I wouldn't go beyond finger tight on plexi (anymore, I broke the top of an ek block a while back), I'll cheerfully go to the limits of what I can sensibly apply with a spanner when screwing into a brass fitting. A radiator is somewhere in between, you're pretty unlikely to pull the threaded insert out, but with enough effort it might happen.
A reasonable rule of thumb is to apply a torque using two fingers only, at the end of the handle close to the nut. Even that will probably break plexi though.
(I don't think plexi should be anywhere near water cooling
)