SOLE S.A. – Solar Collectors – Installation Manual
18
balancing valve in each group, properly adjusted. We recommend the second
system.
The pressure drop within each collector should be taken into account when selecting
the appropriate pump. (figure 21 indicates the pressure drop)
Figure 21.
The pipes must be insulated according to existing regulations. The thickness of the
insulation material must be at least 30 mm for a material with conductivity equal to
0.040 W/mºK. The insulation material must be capable of withstanding pipe surface
temperatures higher than 120 ° C without deteriorat ion.
The circulating fluid must contain a sufficient amount of antifreeze liquid to avoid any
risk of freezing. The freezing temperature of the fluid circuit of the solar collector
should be less than the minimum temperature recorded at the site of the facility.
Propylene glycol makes an excellent choice for use as a heat transfer fluid in
applications where contact with potable water, food or beverages might occur. Its low
toxicity, low freezing point, corrosion-inhibiting composition
and high boiling point
make it uniquely applicable for use in such applications.
Below is a table showing the freezing temp. of propylene glycol – water fluid with
respect to the ratio of pure glycol to the water.
