It can be that the alpha PQ test is not accepted. One reason for failing the PQ is when the internal humidity of the alpha is too high. Hence, you need to change or dry the desiccant in order to lower the internal humidity of the device.
When to change the desiccant?
When the internal humidity exceeds 30%, the reliability of the alpha performance decreases thus, a change in desiccant is needed. The internal humidity can be checked by clicking on the green/orange/red dot (figure 1) in the lower right corner of the SoilWizard software.
Figure 1: Sensor status Figure 2: Interferometer
Then, click on the interferometer (figure 2) inside the instrument status table, and select ‘Service Info’. Finally, check the internal humidity (figure 3) by looking at the number for ‘relative humidity IF compartment (%)’ of the Alpha instrument. When this number exceeds 30,000 a change in desiccant is needed.
Figure 3: Relative humidity inside the alpha compartment in %
How to change the desiccant
First switch off the Alpha and disconnected the power and LAN cables, which are located at the back of the Alpha device. Move the Alpha to an open area and unscrew the 4 screws at the back by using the Alpha screwdriver (figure 4).
Figure 4: Removing the 4 screws at the back of the Alpha
Place the cover carefully with all four screws to the side. The desiccant is placed in a compartment on the right side of the alpha (see figure 5).
Figure 5: Position of the desiccant
Take the desiccant out and dry the packages for at least 30 min in the dryer on 70°C (figure 7).
The desiccant can only be dried 3 times, after that it needs to be replaced.
Figure 6 drying the desiccant in the dryer at 70 degrees
After drying, check if all the stickers on the desiccant packages have turned completely blue again (figure 7).
Figure 7 the desiccant is dried successfully
If the desiccant has not turned completely blue (figure 8) then it can be dried again for another 30 min. If the stickers remain to show a pinkish colour then the desiccant needs to be replaced with a new one.
Figure 8 incorrect colour of the desiccant
To place the desiccant back:
Fold the desiccant in a package and place it back in the right corner at the back of the Alpha. Fasten the 4 screws (see picture 4). Place the Alpha back on its original spot and connect the Alpha with the LAN and power cables. Wait until the alpha is switched on for at least 1 hour. Then contact the SoilCares Service desk and request a calibration for the Alpha.
A calibration by the SoilCares support team is always necessary when the back of the Alpha has been opened!
How to request a calibration:
Send an email to firstname.lastname@example.org and include in the subject ‘Alpha calibration (Lab name).’ In the email you describe that you have dried or replaced the desiccant. SoilCares will contact you with a request for the TeamViewer credentials and perform the calibration.
What you need to do:
- Make sure the Alpha is on for at least an hour after changing the desiccant.
- Send the TeamViewer credentials to SoilCares and leave the software on.
- Place the golden cup inside the Alpha machine.
- Keep the Alpha on.
NOTE: Changes in temperature will attract moisture. Leaving the Alpha on will keep it at a steady warm temperature. This decreases the moisture level and will reduce the number of times that you need to replace the desiccant.