Pressure Measurement

[AgeOfEmpire]

Hi ,

Could you guide me about this problem?

I want to calculate max pressure in the capillary rheometer.And then I will calculate outher diameter of barrel and die for safe.But I can't find true formula for this aim.Max piston load ,barrel diameter die diameter and max-min shear rate values are known but I think P=F/S is not enough for calculate pressure because of viscosity ,shear rate etc.

How can I calculate max pressure in barrel and die?.

Thank you so much your interest.

 

[zekeman]

You usually use the hoop pressure formula for thinwalled cylindrical vessels,
s=pd/2t
where
s=tensile stress in wall
p=pressure
t= wall thickness
d= diameter of cylinder

 

[BobM3]

Assuming you are measuring the force on the plunger rod, I would say P = F/A would give the maximum pressure. The effects of viscosity, shear, etc would reduce the pressure at other points in the cylinder.