[BillA]

worms for breakfast
the test is to determine the correction factor for the hydraulic resistance of the cross plus 6" of tubing used for the instrument and DUT connections
for the test shown the coolant and the ambient were held as close as possible (0.3 to 0.45°)

the connection correction for pressure drop is typical,
the flow effect is puzzling

to preclude some of the obvious; 1/3 DIN RTDs individually/simultaneously caled with their inst using a quartz ref thermometer and a bath (bath thermal pattern cked)

am rerunning for more accuracy, then will reverse to ck
will try a larger tee to drop the velocity around the RTD tip
??

EDIT
units should be lpm in temp 'corr' graph