Column head pressure determination

[Mouat]

Respected,

For GC, I need help in determining column head pressure at specific temp. From Van Deemter plot, I have determined the optimum linear flow rate. We are give parameters - column length, internal diameter & stationary phase thickness.
I searched enough.. all I found was that column head pressure depends on all these parameters, but how? wiki suggests using Poiseuille's equation, however we dont have inlet / outlet pressure readings.

Any help would be greatly appreciated. Thanks!

[Mouat]

Anyone? Please..

[tom jupille]

Inlet pressure = the "head pressure" (is this what you are trying to estimate?)
outlet pressure = 1 atm

The math (which you have already found) is here:
http://en.wikipedia.org/wiki/Poiseuille ... ble_fluids
You know the flow rate, the capillary diameter and length, and the outlet pressure. The only parameter you are missing is the viscosity of the carrier gas at your operating temperature.