Hamworthy Trigon ST1 Installation, Commissioning, Operation & Service Instructions page 26

8 Function check valves [installer]
Do you need to know it exactly?
The density of the solar fluid decreases with rising temperature. In high installations with large
temperature differences, the difference in density will cause gravity circulation. This circulation
can cool down the storage tank.
Calculation example: Δp = Δρ * g * h
Collector temperature:
Storage tank temperature:
Δρ = ρ - ρ = 39.5 kg/m³
1 2
g = 9.81 m/s²
Installation height h = 10 m
Δp = 3875 Pa = 395 mm wc
The two check valves in the station (2 x 200 mm wc) are sufficient for an installation height of
10 m and a temperature difference between the collector and the tank of up to 62 K.
0DNO0201
5 °C  Density solar fluid ρ
67 °C  Density solar fluid ρ
Installation-Operation ST1 Solar Pump Station
= 1042 kg/m³
1
= 1002.5 kg/m³
2
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