Ncstatecamp
Been Around the Block
Finally fed up with looking for a proper petcock (after not really being able to figure out which size it was) I brought my primed tank into a bunch of stores (lowes, Ferguson's, multiple hardware stores) trying to figure what exact thread I had. Turns out with my measurements the tank fit 3 things, 3/4" 18tpi, 20mm 1.5mm, surprisingly enough 5/8" od compression cap http://imgur.com/69Q4fAq, or a (and most importantly!) 3/8 Fe Compression Coupling. These last 2 were perfect fits (WTF is NPT compression thread doing fitting 41 yr old japanese tanks!?!).
So now use a 3/8" Fe compression Coupling to 1/4" compression http://imgur.com/IYu4gMt with an interior 1/4-in x 1/4-in Copper Slip Coupling Fitting http://imgur.com/EPkln9Q inside your 1/4" line. I made the mistake of not using the interior copper fitting the first time and had some leakage. Also make sure to use some telfon tape for some extra assurance.
Next you'll need an inline switch http://imgur.com/lf5gpye and, if you care to use it, an inline filterhttp://imgur.com/8LagsZ3. Before all of this I was using clear 1/4" ID vinyl tubing and it fit all my parts perfectly without hose fittings. Past the inline filter I used wind shield washer hose (7/32" or 5.6mm) http://imgur.com/xVhso32, its essentially vacuum line and the closest I could find to original line without using hose clamps.
This http://imgur.com/vHUw5gP picture is of the complete set up. I hope this helps anyone in need of a petcock alternative.
So now use a 3/8" Fe compression Coupling to 1/4" compression http://imgur.com/IYu4gMt with an interior 1/4-in x 1/4-in Copper Slip Coupling Fitting http://imgur.com/EPkln9Q inside your 1/4" line. I made the mistake of not using the interior copper fitting the first time and had some leakage. Also make sure to use some telfon tape for some extra assurance.
Next you'll need an inline switch http://imgur.com/lf5gpye and, if you care to use it, an inline filterhttp://imgur.com/8LagsZ3. Before all of this I was using clear 1/4" ID vinyl tubing and it fit all my parts perfectly without hose fittings. Past the inline filter I used wind shield washer hose (7/32" or 5.6mm) http://imgur.com/xVhso32, its essentially vacuum line and the closest I could find to original line without using hose clamps.
This http://imgur.com/vHUw5gP picture is of the complete set up. I hope this helps anyone in need of a petcock alternative.
