Selecting the capacity of a diaphragm expansion vessel
Selection of diaphragm expansion vessel capacity
Data
Temperature range: 0°C < t < 100°C
°C
°C
m³
m
bar
bar
m
%
Results
Density of the medium at t1, ρ(t1)– kg/m³
Density of the medium at tz, ρ(tz)– kg/m³
Increase in the specific volume of the medium from t1 to tz, Δυ– dm³/kg
Hydrostatic pressure at the level of the vessel connection (at 10°C), pst– bar
Pre-charge pressure in the vessel's gas space, p– bar
Maximum design pressure in the vessel, pmax– bar
Minimum usable vessel capacity, Vu– dm³
Minimum total vessel capacity, Vn– dm³
Minimum diameter of the expansion pipe *, d– mm
Usable vessel capacity with operating reserve, VuR– dm³
Operating pre-charge pressure of the installation with operating reserve, pR– bar
Total vessel capacity with operating reserve, VnR– dm³
* The standard minimum value (20 mm) was adopted; the exact diameter requires knowledge of the heat output of the heat source.
The calculations were performed according to the methodology for selecting diaphragm expansion vessels (PN-B-02414), using a simplified liquid density model; values for glycol mixtures are approximate. For critical installations, the result should verify with the design engineer.