You are correct about valve in electronics. Valve in chess problems predates electronics, but valve in biology and mechanics (controlling fluid flow) is much older than in chess. I don't have any issue with Reinfeld's glossary -- he documented the term correctly, as it's used by problemists, and wikipedia shows the same definition. I just happen not to like how problemists use the word valve. If I say any more about it I will just be hijacking my own thread. Anyway my opinions about problems and problem themes count for very little in the chess universe.

Yes, thanks. The source for that pdf is wikipedia. 
https://en.wikipedia.org/wiki/Glossary_of_chess

I will be double-checking that list. But I will say I find existing lists of themes to be not well thought out. Sort-of on topic, I recently bought Reinfeld (1968) 101 Chess Problems for Beginners. This also has a Glossary.

Valvular Move - A Black (sic) move that opens one line and closes another. --Reinfeld
valve - A move that opens one line and closes another. --Wikipedia

In my opinion that's hokey for two reasons. First, typically a valve in real life just opens/closes one line. Second, every chess move opens at least one line and closes at least one line. (Almost! I haven't thought about this topic in ages but I just realized a move along the edge of the board isn't a valve.) So should I tag every problem as a valve? You could say I have problems with problem themes. I expect I won't be quite satisfied with extant endgame themes, either.

The Reinfeld book is on the whole not bad. The title is awful, these are not beginner problems. It's basically a reprint of Harley/Mansfield (1958) The Modern Two-Move Chess Problem, which is a far more indicative title. I don't have the original but I would say Reinfeld (in a 1960 edition) probably translated from algebraic to descriptive notation as well. Amusingly, the Reinfeld 1968 edition has a cover diagram with a dark square in the right-hand corner, also the black queen is on the same file as the white king. But we can't blame Reinfeld for that, as he passed away in 1964.

I want to start one.

https://en.wikipedia.org/wiki/Controlled_vocabulary

It's basically a tagging system where the tags are not spontaneous but defined in advance. I've been using spontaneous tags but only sporadically. I have saved too many endgame positions without any tags, but this decreases the value of the data. Now I want to buckle down and start tagging every (new) endgame position with multiple tags. And it's just easier to pick from a list than to think of a tag every time. Examples of tags might be "MustKnow" or "QueeningRace". (I like no-spaces because it's easier to tell if it's one tag or two.) 

If anybody knows of a good vocabulary out there please point me to it. An endgame book with a list of themes would be good, an online list would be better. Eventually I would put the list here so anybody could use it or modify it.