Delta-T Devices PR2 User Manual page 25

Water reading
Insert the PR2 fully into an access tube and immerse the tube
into a large body of water at 20 to 25°C. The water container
should be sufficiently large so that the PR2 is >100mm from any
edge. Take a reading using an HH2 meter, or other meter or
logger. Although this reading is outside the PR2's specified
accuracy range, the reading should lie between 1040 and
1100mV.
Centring springs
Check that the centring springs are all fitted, clean and
undamaged. Immediately replace any that do become
damaged.
Installation problems
Augering and access tube insertion
Most PR2 errors are caused by inserting an access tube into the
wrong size of augered hole.
If the hole is too large, gaps around the tube will result in
generally low readings and poor response to soil moisture
changes – unless the gaps fill with rainwater.
If the augered hole is too small, the effort necessary to hammer
the access tube into the soil will often result in gaps forming
around the tube at the top and compaction of the soil lower down
the tube.
Refer to the Augering Manual for advice on augering holes of the
correct size.
Profile Probe User Manual 3.0a Troubleshooting 25