Knowing the following data:
- The pre-charge pressure
- The set pressure for the safety valve
- The difference in level
- The volume of the fluid in the system
- The maximum working temperature of the system
- The possible percentage of antifreeze glycol in the system fluid
it’s possible to calculate the required volume of the expansion vessel.
- The calculation is valid in the hypothesis that the initial pressure (hydrostatic pressure) on the expansion vessel is not higher than the pre-charge pressure. On this point, consider that a water column of 10 meters exerts a 1 bar pressure.
- The difference in height (meters) is the difference between the position in which the safety valve is installed and the position of the vessel. Enter a positive difference if the valve is located higher than the vessel, negative otherwise.
- The set pressure for the safety valve, summed to that one due to the possible difference in height, must be lower than the maximum working pressure of the vessel.
- The calculation (compliance to EN 12828, VDI 4708) provides only an indication of the required volume of the vessel and must be checked by a qualified and authorized technician.