Constant Head Permability Calcs

Question 1

In the constant head permeability test, what is the formula for ‘k’?

Answer 1

k = ( Q x L ) / ( t x A x change in h )

Question 2

How is area, A, calculated?

What are the units?

Answer 2

( Pi x sample diameter ^2 ) / 4

mm^2

Question 3

The flow quantity, Q, is often given in ml, what is the conversion factor from ml -> mm?

What are the new units of Q when calculated?

Answer 3

x 10 ^ 3

mm ^ 3

Question 4

How is the time, ‘t’, calculated?

If the time is given as 3 minutes

What are the units?

Answer 4

The time is calculated by multiplying the minutes by 60, 3 x 60 = 180 sec

s, seconds

Question 5

Using the constant factors in the equation, you are left with:

k= calculated value x ( ? / ? )

Answer 5

Q / change in h

Question 6

When the average value of k is calculated, what units should it typically be presented in?

By what factor must the original units (mm/s) be multiplied by?

Answer 6

m/s

x 10 ^ -3