Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 59)

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6.0 Maintenance
6.1 Introduction
High quality, consistent on-site m aintenance is crucial if accurate long-term records are to be obtained.
Not only does the individual have to care for the instrum ents, they m ust also carefully docum ent any
work that they do on those instrum ents. It is not good enough to assum e that instrum ents are cleaned
regularly; this activity m ust be properly docum ented. To help in this docum entation, sam ple log sheets
are reproduced in Annex G. Many national networks have developed their own m ethods of docum entation
and these can be used if they contain the appropriate inform ation for the radiom eters. ALL MAINTENANCE
PROCEDURES, VARIATIONS IN INSTRUMENT BEHAVIOUR AND CHANGES IN INSTRUMENTATION
MUST BE FULLY DOCUMENTED WITH RESPECT TO ACTIVITY, TIME AND DATE.
6.2 Daily Maintenance
The m inim um daily requirem ents for m aintaining a BSRN radiation station are as follows:
(1) Cleaning:
(i) Active Cavity Radiometers: Radiom eters fitted with a protective optical flat should be
cleaned using a soft cloth and/or a photographer’s airbrush. Material adhering to the
surface of the optical window should be rem oved using a soft cloth dam pened by either
deionized water or m ethyl hydrate (or equivalent). If the window is other than glass
or quartz, the type of solvent used for cleaning the m aterial m ust be checked before
applying it to the surface. Care should be taken to ensure that no build-up of m aterial
is found at the border of the flat with the flange holding it on the instrum ent. When cleaning
with any type of liquid, it is essential that no film or residue be left on the surface. The
general procedures outlined below should be followed if frost or ice is on the window.
For cavity radiom eters without protective flats the area around the opening aperture
should be inspected and any foreign m aterial should be brushed away from the opening.
(ii) Pyranom eters and Pyrheliom eters: The exterior of dom es or optical surfaces of each
instrum ent m ust be cleaned at least once per day. It is preferable that this cleaning
is done before dawn. However, if this cannot be accom plished, the sensors should
then be cleaned as early as possible during the day. If possible, the instrum ents should
also be cleaned following the occurrence of any form of precipitation or atm ospheric
events that would cause degradation to the signal. Each tim e an instrum ent is cleaned,
the tim e and duration of the cleaning should be recorded in the site docum entation.
All loose dust or particulate m atter should be blown off gently (a cam era brush is a
useful tool) before the dom e is wiped. Using a soft lint-free cloth the dom e should then
be wiped clean. If any m atter is adhering to the dom e, either deionized water or m ethyl
hydrate (or equivalent) should be used to wet the cloth before cleaning the dom e. Do
not pour the liquid onto the dom e directly. Caution m ust be used so that the dom e is
not scratched, nor the instrum ent m oved, during this procedure. Any film left from the
cleaning m aterial m ust to rem oved.
Several m ethods m ay be used to rem ove frost or ice from the dom e, depending upon
the severity. Light deposits can be rem oved by lightly rubbing the surface using the
lint-free cloth as in norm al cleaning. Heavier deposits can be rem oved by using a m ethyl
hydrate solution on the cloth. W here an ice build-up cannot be rem oved with m ethyl
hydrate alone, the observer (depending on weather conditions) can m elt the ice by
placing his hand on the dom e. In severe cases a hand-held hair dryer can be used.
In the m ost severe cases the instrum ent should be rem oved and brought inside to thaw.
Using any sharp objects to chisel away the ice is NEVER appropriate. In cases where
the ice is m elted by whatever m eans, the dom e should be cleaned with m ethyl hydrate
and then wiped with a clean lint-free cloth following the operation. The procedure used
and the tim e required should be docum ented.
W hile cleaning the dom e, an inspection should be m ade to decide whether any scratches
or chips have occurred since the last cleaning. Such m arks are m ade by scouring of