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graph of a pressure ratio

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.

RE: graph of a pressure ratio

Rearrange the equation slightly.  It's a little tough without making explicit assumptions on the order of your operations, but I'm going to assume your equation is:

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

(OP)
The main problem is that permeability depends on the partial pressure.

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

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