Lesson learned today...Place a deflector over the AMNPS...

I put a couple of pork shoulders in this morning, placed them over to the right of my MES, and put my AMNPS on the bottom left.  Let them go for about 3 hours, and then put a rack of baby back ribs on the top rack.  It stretched all the way across the smoker.  Looked again in another 3 hours, and EACH of the 3 rows of the AMNPS were about 2/3 burned.  That's gonna be some smokey meat!  I can only imagine that the fat from the ribs dripped on the pellets, and caused all three rows to ignite at once.  

What kind of methods have you guys used to prevent this?

Thanks,

Allen