Low-level salvage is lv10-25. Mid-level is 26-40. Upper level is 41-53.
Edit: Whoops. those are the levels of recipes using those tiers. Stargazer's numbers are correct for the drop levels.
http://www.fimfiction.net/story/36641/My-Little-Exalt
Paragon Wiki to the rescue.
For each type (Tech, Arcane), the three tiers are according to Paragon Wiki lvl 4-25, 20-39 and 35-54 respectively (level of the mobs that can drop them).
Thanks a bunch. I knew I would feel silly asking that I did find salvage descriptions on the wiki but my search fu is very weak and I didn't see the chart you linked.
I've been away for a looong time and just came back to all the new cool stuff. I made a dual build and went to create a mess of IOs to populate the slots. It seems that the lower level salvage can be hard to find so finally my question. Is there a source that tells the level of certain salvage so I know what alt to mission with hoping to get some pieces?