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58
AST 14 C 255/00
The curves given in the above diagram refer to a request of a “fictitious ambient
temperature” of 20°C.
In case of different fictitious temperature, all curves are shifted in a parallel translation:
Example of curve shifting with P10=1.5 and ambient
fictitious temperature from 20 to 25°C.
Curves can be chosen proceeding either roughly and approximately or using a simple
mathematical formula. In either case, it will be necessary to check the temperature
changes so as to correct and choose the proper curve accurately.
In the former case you will simply need to take an actual value of external temperature
and associate the desired flow value to it. Then choose the closest curve.
Example:
at an external temp. of -4°C, a flow of 62°C is required; curve: 1.5
In the latter case use the following formula:
CURVE
Testmin
20
20
Tmax
Where, Tmax is the maximum flow temperature and Textmin is the minimum external
temperature.
Example:
Low temperature: High temperature:
Tmax = 44°C Tmax = 70°C
Text = -10°C Text = -10°C
CURVE
(-10)
20
20
44
CURVE
(-10)
20
20
70
P10 curve = 0.8 P10 curve = 1.7
+5
-5
