graph of a pressure ratio
graph of a pressure ratio
(OP)
I have an equation that is basically
Permeability = Constant/time x ln (Pressure ratio)
Pressure ratio is:
(Pressure Outside- Pressure at some time)
divided by
(Pressure Outside - Pressure initial)
Anyhow, when I am interested in obtaining a value of the permeability. I have data showing pressure differences with respect to time. If I graph the ln of the Pressure Ratio with respect to time what will this tell me?
Any other help is appreciated.
Permeability = Constant/time x ln (Pressure ratio)
Pressure ratio is:
(Pressure Outside- Pressure at some time)
divided by
(Pressure Outside - Pressure initial)
Anyhow, when I am interested in obtaining a value of the permeability. I have data showing pressure differences with respect to time. If I graph the ln of the Pressure Ratio with respect to time what will this tell me?
Any other help is appreciated.





RE: graph of a pressure ratio
Permeability = (C/t) x ln(Pressure Ratio)
So, rearrange to:
t = (C/Permeability) x ln(Pressure Ratio)
If C and Permeability are constants, then the slope of this line (it will be a line) is C/Permeability. Solve for Perm.
RE: graph of a pressure ratio
My setup is basically a milk carton with water in it. I have purged the dissolved gases out of the milk carton. Over time the milk carton leaks (permeable) the dissolved gases back in (oxygen is what I measure). I have data showing dissolved oxygen readings with respect to time. It is not linear.
So if I graph the ln (Pressure Ratio) vs. time, does this info give me any useful info.
Using the equation that I listed:
Permeability = Constant/time x ln (Pressure ratio)
My data is as follows:
Recorded Data
Net Time Temperature Permeability
(hours) (C)
0.27 21.3 2.58E-18
0.47 21.4 2.13E-18
19.98 23 3.25E-19
38.22 25 1.87E-19
61.97 25 2.18E-19
89.38 23.7 2.59E-19
121.80 22.7 3.20E-19
161.30 25.3 3.29E-19
190.30 22.9 4.26E-19
213.05 23 4.87E-19