6.1.5 Solar Fluids.
If water quality is poor, water treatment equipment may be used. The product water
from the treatment equipment should be checked.
Usually, water is "softened," to remove scale-causing "hardness." Typically, this is
done with ion-exchange softening equipment. Test for hardness with any standard
water hardness test equipment.
Sometimes iron is a problem. Standard ion-exchange softeners, specialized iron
filters, or chlorine-based treatments are used to remove iron. These can all be
easily checked with a test kit for total iron (both ferrous and ferric iron).
Check for the recommended pressure from the system's operation and maintenance
manual. If no such manual exists, Section 5.2.6 includes a chart of recommended
Glycol-based fluids should be checked for glycol concentration and the condition of
the corrosion inhibitor. If these two cannot be checked, at least check the pH
(acidity/alkalinity) of the fluid.
To check glycol concentration, some manufacturers (including Dow Chemical
Company) furnish simple test kits with simple test strips and color charts. Another
method is an optical refractometer. Both these methods only require a few drops of
fluid and are quite simple.
To check the condition of the corrosion inhibitor, measure either the pH or the
reserve alkalinity of the fluid. Most glycol manufacturers recommend that the pH
should not drop below 7.0 and the reserve alkalinity should not drop below 8.0.
Should either condition be too low, the fluid must be replaced or reinhibited.
To check the pH, use pH paper or tape, or have a laboratory analyze the fluid. If
using pH tape, use fairly fresh tape with a pH range from 6.0 to 8.0. Water
treatment specialists or swimming pool chemical suppliers are good sources for pH
tape. To check the reserve alkalinity, use a special test strip from the manufacturer,
or have a lab check it.
6.1 MAINTENANCE PROCEDURES