ehm... i understood what was the problem. inside the "Nozzle flax", "Fluid SG" i put 900 as i did in "fluid density". so the Fluid SG is:

water=1 (and fluid density 1000kg/m3)
hot oil=0.9 (and fluid density 900kg/m3)

is it right?

caesar help reports:
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i thought it was the same of fluid density