Compression fitting from dip tube not air tight

[petep1980]

I am just looking for tips or must knows for compression fittings. When I assemble it, I don't really see how it holds air tight because it seems like the dip tube can still move around in it.

Any advice?

 

[PantherCity]

They are certainly air tight if you tighten them down. You have to really crank down on them to compress the ferrule into the tube. Put some lube on it and tighten it again. Then wash clean. The ferrule is the small ring that goes around the tube inside the nut. Once it is tightened the ferrule will dig into the tube and the nut will not come off the tube.
Are you talking about copper or SS? The SS will require alot more torque.

 

[petep1980]

SS. I was hand tightening. I'll torque the **** out of it next time.

 

[poislb]

Compression fittings suck, end of story...sweat if ya can, compressions fittings are hit or miss. But like the previous post, do use lube on compression fittings, does make a world of difference.....

 

[petep1980]

Compression fittings suck, end of story...sweat if ya can, compressions fittings are hit or miss. But like the previous post, do use lube on compression fittings, does make a world of difference.....

What do you mean by "sweat it"? I am new to this stuff. I'm also a mech engineering student, and I feel like I really need to learn this stuff.

NM, I looked it up, soldering. I got that. I can't do that because I need to be able to disassemble this thing for cleaning.

 

[samc]

Properly size tubing, correct OD, ID and material works all the time with a compression fitting. Never had a failure.

 

[rcrabb22]

I am just looking for tips or must knows for compression fittings. When I assemble it, I don't really see how it holds air tight because it seems like the dip tube can still move around in it.

Any advice?

I would use silicon (2) o-rings instead of a ferrule if you plan on periodic dis-assembly for cleaning. o-rings will form a seal and can be reused or replaced without permanently crimping the tube like a ferrule will when cranked down.

I have hit or miss luck reusing a compression fitting with the ferrule more than once.

 

[petep1980]

It worked fine in a test run with applying adequate torque. Now I need to trim the diptube because it's up too much against bottom of kettle.

 

[theonetrueruss]

Really, your dip tube needs to be pretty air tight but It doesn't have to be absolutely 100% perfectly sealed. So what if a tiny amount of leakage would happen over time... you won't lose that much pressure in the context of what a dip tube does. Hand tightening should be fine. Try it with water and see if you are getting an adequate siphon effect. IF you are then don't worry about it.