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Technical Data for Expansion Vessel

Information about the technical data dialog for expansion vessels.

This dialog allows you to dimension diaphragm expansion vessels according to EN 12828.

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Technical data expansion vessel Linear Revit

Name

Specifies the name of the component. You can modify the name. Clicking restores the default setting.

Manufacturer, Order number

These fields are freely editable. This data is displayed in parts lists.

Calculation of Expansion Volume

To calculate the expansion volume Ve of the expansion tank at maximum operating temperature, enter the partial volume of system, the filling temperature and the maximum operating temperature of the system. Expansion is calculated using the medium table and is thus correctly adjusted when using a medium different from water.

The Partial volume of system is calculated by the pipe network calculation and consists of the fluid content of the calculated pipe network: the content of the drawn and possibly edited pipes, radiators, tanks, potable water heaters, general consumers and partial network ends. If more than one expansion vessel exists in the system and the tank is to be dimensioned for only part of the system or if the actual system volume deviates from the calculated value you may edit this value. Activate the checkbox and enter the desired value. Deactivating the field resets it to the calculated value.

Water temperature at the time of filling is suggested to be 12 °C but can be edited.

Maximum operating temperature is taken from the supply water temperature of the system’s heat generator. Activate the checkbox in case this value needs to be changed. Deactivating the field resets it to the original value.

Safety relief valve

Relief pressure of the safety relief valve psv is suggested to be 2.5 bar. Enter the relief pressure of the safety relief valve used. From this value the dimensioning end pressure of the system pe is calculated. If psv is smaller or equal to 3.0 bar, pe is reduced by 0.5 bar. If psv is larger than 3.0 bar, pe is reduced by 10 % bar.

Pre pressure calculation

The System height above vessel is taken from the model. The static pressure of the system is calculated using this value. Activate the checkbox to change this value. Deactivating the field resets it to the calculated value. Enter the cut-off temperature for the safety temperature limiter from the heat generator in the field Temperature limit (STL). A maximum value of 105 °C is suggested for the scope of DIN EN 12828. From these values, the pre pressure p0 required when installing the expansion vessel is calculated.

Expansion vessel volume

The values for Compensational water Vc and Expansion volume Ve are calculated and can not be edited. The compensational water comprises 0.5 % of the partial volume of the system, or at least 3 L.

The nominal volume Vn of the expansion vessel is derived from that value. The calculated value relates to the minimum vessel size, where start pressures ps min and ps max are equal. When filling the system, exactly this pressure has to be set.

The calculated nominal volume usually is not a commercially available size. Activate the checkbox Nominal volume and select the next greater commercially available size for the expansion tank. As a result, a difference between psa,min and psa,max emerges. The start pressure when filling the system should be set within those limits. As soon as the difference between psa,min and psa,max is equal or greater than 0.2 bar for the selected nominal volume, the note displayed will confirm that the nominal volume selected is sufficient.