Thanks for the confirmation. I figured these would be the ticket, and ordered some of these a couple weeks ago from another outfit (ironically they arrived today...from dreamworks ) without realizing DW had them.
I wasn't sure if these were one way check valves, or if they could be used on both up and down lines. The solution seemed almost too simple, hence my asking.

glad I could help they make great fill valves to

hello Sean how are you keeping.All the best.