Check out Penn State Industries. I have one of their Cyclone units, with the stand up micron filter. All my piping is metal, and, as long as you have enough distance between your spark source and your collector, you'll be fine.
Some guys build water traps, that's another way to go. I have found that, if you design and position your traps correctly, in a short time, you get a build-up of swarf that tends to catch the hot particles before they get sucked all the way thru the system anyway. I'll just wet the swarf pile with a handful of H20 from the dunk bucket when I'm making hot sparks and it does the trick.
Grinding Ti at a low belt speed is a really good idea as well. It really cuts down on the spark temperature and volume.