Attaching a coupling to a copper pipe

Question

I am trying to install a standing bottle-less water filter in my house and the hoses beneath my sink are incompatible with the adapters that come with my filter. My fridge does not have a water dispenser (which is the other recommended way to connect the filter), but there is a pipe that carries water into the fridge. Since it neither has an ice machine nor a water dispenser it is effectively doing nothing.

The manual to the fridge explicitly says connecting water to the fridge does nothing if it doesn't have an ice maker, so I know removing the pipe from the fridge won't cause any issues on a theoretical level.

My hope is to be able to connect the 1/4 inch plastic tubing that comes with the filter to this copper tube. I got a 1/4 inch coupling in order to do this, however nothing I do seems to work. Neither the nut, the inner tube, nor the inner compression thing will go around the copper pipe. If I remove the nut from the coupling and use the compressor and the nut already on the pipe, this connects to the central coupling. This seems ok. The issue is when I connect the inner tube, compressor and nut to the plastic tube and screw that into the inner coupling, water just gushes out the side on the plastic tube.

The guys at Home Depot advised me to scrap the entire copper tube and replace it with a plastic one which at the minimum seems like overkill, but they were adamant that nothing else will work. Below is an image of the plastic tube with the nut and inner tube (I have 2 couplings at this point since once I assembled the side with the plastic tube it was impossible to take off and I got an extra coupling).

For clarity when I say the water gushes out the side, I believe the inner compressor and the nut is where the leaking water is coming from, not around the seams of the nuts. Water does come out of the end of the plastic tube the way I would want, but obviously due to the leaking this is not a workable situation. I don't know if there is some kind of glue or magic tape that I can use around the nut to prevent leaking, but that is the kind of advice I am looking for (or if I am doing something fundamentally wrong guidance in the correct direction would also be appreciated).

Does anyone have any suggestions for me?

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Answer 1

I am not quite sure just what you are trying to do but from the picture you posted, the fitting on the top is a standard fitting for utilizing 1/4" OD plastic tubing and the bottom fitting is a standard 1/4" OD compression fitting. To use the top fitting with plastic tubing you cut the end of the tubing with a sharp object for a clean cut. Then, you slip the compression nut onto the tubing, then the 1/4" OD compression furrel. Next you push that small brass sleeve into the end of the tubing. Place the now adapted plastic tubing into that compression fitting (union) and tighten the compression nut. That small sleeve gives the plastic tubing strength to allow the compression nut to seal between the plastic and the nut. By the way, do not use the bulk type tubing, only use the tubing sold as ice maker tubing. That other stuff can break and cause water damage as I found out the hard way.