I have a had a real hard time with Definox. Took me way more time then it was worth. When and if you do get a hold of them they will refer you to a local company that carries their parts. That company (at least two different ones in my area) did not know they were Defontaine dealers. Then I was told they no longer made that size PRV. So I bought new ones from another company. Funny thing is the next tank we ordered had exactly the size Definox PRV on it as the one I was looking for.
CBO "Chief Brewing Officer" / Zymurgist
Bluegrass Brewing Co
636 East Main St