Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 63)

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6.3 W eekly Maintenance
The m inim um weekly requirem ents for m aintaining a BSRN radiation station are as follows (in addition
to the daily m aintenance):
(1) Check the desiccant in each sensor. Desiccant should norm ally last several m onths, but is
dependent upon atm ospheric water vapour, the quality of radiom eter seals, the size of the
desiccant cham ber and the quality of the desiccant. In drier clim ates checking the desiccant
m onthly m ay be sufficient while in areas where m onsoon conditions occur, twice weekly
inspections should be m ade during the m ost hum id season. Depending upon the type of sensor
and the type of ventilated housing, the shield portion of the ventilator m ay require rem oval
to check the desiccant. Once checked and replaced if necessary, the shield should be carefully
replaced ensuring that the top of the shield is below the level of the instrum ent receiver surface.
W henever possible, desiccant should be changed during conditions of low relative hum idity.
If the desiccant is not a bright blue/purple, it should be changed. Desiccant can be recharged
by drying. Therefore, no saving is gained by attem pting to have the desiccant last another
week. The material rem oved from any instrum ents should be saved and re-activated by placing
in an oven at a low heat for several hours. The desiccant will return to its original colour when
dry. Desiccant should be stored in an air tight container.
(2) If not part of the norm al data acquisition program , the resistance of each of the instrum ents
should be checked and recorded. Significant changes in resistance can be used to detect
system faults.
(3) If not part of the norm al data acquisition program , a reference voltage source and reference
resistor should be used to test the stability of the response of the data acquisition system .
This should be repeated at various temperatures to determ ine the effect of tem perature changes
on the data acquisition system when such system s experience tem perature extrem es (e.g.
data loggers kept in unheated outdoor enclosures).
6.4 Long-term maintenance
6.4.1 Sem i-annual m aintenance
(1) The pyranometers used for the m easurem ent of global and diffuse radiation should be swapped.
For m ore inform ation please see Section 8.3 on calibration.
(2) The pyrgeom eter should be replaced for calibration. For details please see Section 8.4 on
calibration of pyrgeom eters.
(3) Any wiring that has becom e cracked or brittle should be replaced. Any connectors that have
begun to corrode should be replaced.
(4) A careful inspection of all instrum ents should be m ade to determ ine aging. If radiation shields
etc. have begun to show signs of aging (brittleness, discolouration etc.) they should be replaced.
Pyranom eters should be checked for excessive weathering, O-rings checked and lubricated
etc.
(5) All-weather housings for cavity radiom eters should be cleaned and any internal electrical
connections checked and repaired as necessary. All weather-tight seals should be checked,
lubricated or replaced as appropriate. Fans m otors should be check and lubricated or replaced
as necessary. Any other m oving parts should be checked and lubricated according to the
m anufacturer’s recom m endations.
(6) Som e trackers require sem i-annual m aintenance. Check with the m anual provided with the
tracking device to determ ine these requirem ents.
(7) All seals in weather-tight enclosures should be checked and lubricated or changed if necessary.