[BillA]

Les
yes, but there may be an offset - I need to think for a bit on it
may be ok ??
thinking of the swapped offset described in "C"

Incoherent
the instrumentation 'cross' is actually a modified tee, to function as a cross, with the branches having a RTD port and a pressure tap
the crosses are on either side of the DUT and are shown bare in the first post and as now insulated below

the measured difference is a steady state avg (peak to peak / 2) between the inlet and outlet
(from the RTDs within the crosses, each corrected per its cal on that inst)
equip kinda pushed to get these values
want the spreadsheet ?

EDIT
the temps are NOT a simultaneous difference but independent max-mins,
the lag varies with velocity
lag