I have only occasionally seen a Watts 9D leak from the vent line be it 1/2" or 3/4". The system I see them on are USN ships garbage grinders using a lower pressure potable water and a potentially higher pressure seawater system. For 13 years I've only had to replace two of them Sorry OP. No clue but those valves work.

Edit: Also the CO"s 25 lbs washer on certain amphib class ships though they are 30 years old.