First mistake was going to Lowe's instead of Home Depot.....:B:B..
Seriously though....where does the pipe go that was split? Also, have you determined why it split? It's important to know if it's water pipe or not. It's also important to determine why it split as you might have to check other components of the system for failure. Finally, can you cut out a portion of the piping where the split occurred? Obviously, the pipe at the split will have been compromised so it won't be it's former size at that point. Above and below the split will be your best determinant. Rigid copper pipe is standard size and yours should be no different. I would not hesitate to use the "Shark Bite" fittings in my coach. I believe Lowe's refers to them a "Gator Bites" but they're the same fitting(s). Give us some additional info and perhaps we can help more....Dennis