Kipp&Zonen CHP 1 Pyrheliometer - Manual (Page 9)

9
3 MAINTENANCE
Once installed the pyrheliometer needs little maintenance. The window must be cleaned and inspected regularly,
ideally every morning.
A periodic check is to ensure that the silica gel desiccant is still coloured orange. When the yellow silica gel in the
drying cartridge is turned completely transparent (normally after several months), it must be replaced by fresh silica
gel as supplied in the small refill packs. The content of one pack is sufficient for one complete refill. At the same
time check that the radiometer mounting is secure and that the cable is in good condition.
Some tips when changing the desiccant:
Make sure the surfaces of the radiometer and the drying cartridge that touch the rubber o-ring are clean (corrosion
can do a lot of harm here and dirt, in combination with water, can cause this);
The rubber o-ring is coated with a silicon grease to improve the seal. If the rubber o-ring looks dry apply some
grease to it (Vaseline will also do);
Check that the drying cartridge is tightly threaded into the radiometer body.
It is very difficult to make the radiometers hermetically sealed; so, due to pressure differences between the inside
and the outside of the instrument, there will always be some exchange of (humid) air.
The radiometer sensitivity changes with time and with exposure to radiation. Calibration every two years is advised.
Further information about Kipp & Zonen recalibration services can be found in Appendix VI.