sensing the temperature of reaction products at {TAIL ~ said outlet side} of {HEAD ~ said tube bundle}; and 
sensing the temperature of reaction products at { TAIL ~ said outlet side } of { HEAD ~ said tube bundle } ; and
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH