Hi---I am going to have to replace 3 valves on a system that is 24 yrs old. I have no idea what brand of valves are in place now---can't find a name on the first one I have dug up. I think I might just have to replace the diaphragm but I don't think I can determine the maker--plus it's so old! So, I have read your advice as to what brand to buy---and I am resigned to digging more in our rock hard ground---but my next important question is---how do I determine the diameter of the pipe? It is plas...
