What threading type is my ice maker shut off valve?

Question

In my new apartment, I moved in to find the water dispenser in the fridge is not working. I quickly diagnosed the issue by moving the fridge away from the wall and finding that there is a water line coming out of the wall with a shut off valve at the end, but it is not connected to the fridge. A quick try convinced me that I cannot directly connect the free male end of the shutoff valve with the male end I found on the back of the fridge. The issue seemed pretty standard, as I found many online sellers selling an "ice-maker supply line" with female compression ends that seemed like they would do the job.

When this part arrived, I was able to connect it to the fridge with minimal trouble, but it would not connect to the shutoff valve no matter how hard I tried. Eventually, I discovered that even though the nut seems like it is the right female counterpart to the male threading on the free end of the shutoff valve and is almost a correct fit, it is not. In fact, the two sides of the shutoff valve are not equivalent, with the side connected to the water line coming from the wall being the correct counterpart to the female ends of the "ice-maker supply line" I ordered. So, it seems that I need to get an adapter to go between the two, but it would help to know what exactly I am looking for, since I can't take the shutoff valve with me to the hardware store. Can anyone help me identify the threading type I am looking for? What are the dimensions I need to measure to confirm the identification?

Answer 1

One side of your needle valve is 1/4" compression thread, that is the side with tubing connected to it. The watertight connection is accomplished when the compression nut squeezes down upon and cinches the compression ferrule (a brass sleeve that fits over the tubing) tightly to the tubing.

The other end is 1/8" NPT (National Pipe Thread). NPT fittings seal by the taper of the thread (with teflon tape or pipe thread compound to facilitate) and are utterly incompatible with other types of threaded fittings.

You will likely need an adapter to fasten the valve to "the male end... on the back of the fridge". If you post a picture of that end we might be able to tell you the type of adapter you need.

Answer 2

As @jimmy Fix-it said, I would just replace the valve or you could go to the "big box store" and ask for a 1/8" or a 1/4" female X 1/4 OD compression fitting. These are a standard fitting and easy to purchase. The end of the valve looks to be 1/4" male thread. Make sure that you some type of pipe dope on the threads. I strongly recommend that you buy only an ice maker tubing kit. I purchased a generic kit a few years ago and the tubing broke a year or so later causing a lot of water damage.