Problems appear to be caused by hot spots, short circuits or {TAIL ~ fluid composition deviations} coming from {HEAD ~ the upper reaction bed} 
Problems appear to be caused by hot spots , short circuits or { TAIL ~ fluid composition deviations } coming from { HEAD ~ the upper reaction bed }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD