I have a 12" tube that I love. I use a kitchen creme brulee torch to get it started, let it flame for about a minute, then blow out the flame. (I think the directions say 10 minutes, but I've never gone over a minute.)
Full tube smokes for 4 hours, 1/2 tube for 2 hours, etc.
I use it for cold smoking cheese and bacon with the pellet grill off. I've never used it for additional smoke with a burning pellet grill.
Family loves the smoked cheese - doesn't have a bad flavor at all.