13
First read the left flow meter 60- 600 cm³/min (=0.06...0.6 l/min).
Try to regulate the pressure in combination with an air flow in the range of 300...600 cm
3
/min.
If the reading is higher then 0.6 l/min, open the middle valve and close the left one.
Read the middle flow meter range 0.2...2.0 l/min.
If the reading is higher then 2.0 l/min, open the right valve and close the middle one
Read the right flow meter range 1.0...10 l/min.
Check the thermometer to be sure that the transported air temperature trough the sample is (nearly) equal
to the surrounding climate.
d. Note the measured values; … l/min @ … mmH
2
O @ … °C.
Keep measurement time as short as possible (max. 2 minutes) as the airflow will dry out the soil
sample.
Temperature from a compressed air source can differ significantly from ambient temperature and will influence
the result.
Always read the pressure gauge and flow meters the same way so you can make a reliable comparison between
different samples and measured values.
Flow rate is then measured against the flat top edge of the float.
If for some unexpected reason the pressure exceed the maximum range of pressure gauge, then the water will
be drained into the plastic bottle at the backside of the apparatus.
Prevent exposure of your face above the sample during pressure build-up.
Prevent applying pressure with all valves closed. Serious pressure build-up can destroy the samples
or cause a dangerous situation during opening one or more flow meters afterwards.
Never block openings like tube to bottle. This leads to disfunction or dangerous situations.
