why gamma scan can't detect MTZ ??(Samiran pls help).

[nong]

Hi,
Do u remember my thread about Dehydration Performance Monitoring? U said gamma scan just told whether beds are lifted or not but won't tell anything about density profile. Vendor said they can detect dif density up to .00036 g/cc.
I cal from useful cap = 6lb/100lb bead == 0.015 lbH2O / in3 pore. Is it possible ?

Thank you
Nong

 

[Samiran]

nong,
I didn't understand clearly your last statement. Pls clarify. I now understand neutron back scatter can identify moisture. However, both these methods will not work in very thick vessel walls. Pls verify with the vendor.

Samiran

 

[nong]

Samiran,
Vendor said gamma can detect change in intensity 5% which in theory it's able to detect density change up to 0.00036 g/cc inmaterial thickness 227cm ( dI/I*100 = -u*x*dP*100, u=0.036cm2/g, x=227,dI/I=0.05). Then I cal from bead properties can adsorb H2O 6lb/100lb bead, bulk den =0.8kg/lit, hence bead bulk vol 56.8 lit should ads H2O 6 lb = 0.048 g/CC ) Can I assume that density diff between dry and wet density = 0.048 g/cc so gamma are able to tell dens profile of bed. From equa, I wonder why the more thickness, the more diff density can detect ? Besides, my vessles thick 2" with insulator 3.5", I'm afraid it'll be a problem.
Thank you very much for your helps!

PS: Neutron backscatter has depth limited at 150 mm