Apparatus for monitoring the accumulation of particulates on {HEAD ~ the lining} of {TAIL ~ an exhaust duct} or the like for a combustion device, comprising: 
Apparatus for monitoring the accumulation of particulates on { HEAD ~ the lining } of { TAIL ~ an exhaust duct } or the like for a combustion device , comprising :
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH