Try Score's test facilities in Scotland.
Contact Mr. Steve Abel at steve.abel@score-group.com or +441132898436 and tell him kind regards from Hans Gustorf.
As you probably know, searching the web one can find many testing facilities and laboratories, but most of them are in the USA (mainly in Texas); the above mentioned ones are not in BeNeLux, but at least in Europe...
This fire facility, of course, is not dedicated to valves, but I think that CTSB is able to set up the tests you need (maybe we'll contact them for a NSF 61 approval, for instance...).
They surely perform fugitive emissions testing (see RichDavis' post of April 7th, 2005 on Thread408-115884), they probably are able to carry out many other types of tests (try typing "valves" into the search motor...).