Retrotec FanTestic Integrity (Venting Calculator) - Manual (Page 26)

rev-2014-10-27
Page 26 of 29
©Retrotec Inc. 2012
Choose the % of the enclosure leakage available that will be used as part of the leakage for peak
pressure relief.
4 Calculate Pressure Relief Vent area needed
Enter your data into all the yellow boxes – the yellow boxes indicate required entry items without
default values. They will turn green after entry.
Click the “Calculate” button once all the data is entered in order to view the results; gray boxes show
the calculated results and are not editable.
Pressure relief vent area is the size of the vent that will be required, already taking into account that the
specified percent of enclosure leakage will also be available for peak pressure relief. This additional
leakage needs to be put in place so that Peak Pressure can be lowered to the point where the structural
integrity of the enclosure is not compromised during agent hold time
4.1 Case of Inert gas extinguishing agents
Only positive pressure relief will be needed, so that is all that is calculated.
4.2 Case of Halocarbon gas extinguishing agents with FSSA and FIA:
As long as data is available defining the Leak to Volume ratio for the agent, both positive and negative
pressure relief area will be calculated. All the agents in the list have data.
4.3 Case of Halocarbon gas extinguishing agents with VdS:
VdS equations assume only positive peak pressures will occur, so no negative PRV area can be
calculated, even though experiments show that negative peak pressures usually form.