And magma.
I have read over and over on the forum that wooden pumps deconstruct spontaneously if used to pump magma too long, but had use them in a pinch and never had an accident, so for science I did an experiment and set up a completely wooden screw pump to pumping magma and left it run to see how long it lasts... Well 3 elven caravans have expired in my trade depot since I pulled the lever and still no spontaneous gooey flaming fun has occurred, so I am going to go out on a limb here and say that, as long as magma does not actually occupy the same tile as the pump and the pump is not situated with both its tiles over flowing magma, wooden pumps are safe for pumping magma, just like any other pump made from non-magma safe material..
-Update (for those who don't want to scroll down through all my spam):
It appears that flowing magma under the pump will cause it to explode. So far my testing has shown that it has to be flowing under both tiles of the pump to cause it to catch fire, and that as long as I keep 1 tile of the pump free from magma below then the pump keeps pumping. Testing in temperate to hot biomes have all shown the same repeatable results, regardless of on the surface or below ground.
And yet the science continues! I know that at this stage in the game the point of researching this is probably moot, since there are likely changes in the new version which will make the mechanics of pumping magma with wooden pumps a completely different situation, but I am trying to figure it out anyway, just because its something that has been nagging at me for a while I guess.