The fuel system on the Puma and Super Puma are pretty much the same. The vent system is identical, as are the anti-spill valves.
I served in Iraq at the secret airbase with the Puma fleet and I am now a type rated engineer on civilian Super Pumas.
I do recall in 2007 having to service these valves and I have also serviced them on Super Pumas more recently.
They are not an NRV as such but a ball that rolls in to a slot when the aircraft tips over stopping fuel from spilling out of the vent lines.
I do have a diagram from my type course notes as the the new EC225 has the same system( If it's not broken, why fix it)