Retrotec FanTestic Integrity (Venting Calculator) - Manual (Page 16)

rev-2014-10-27
Page 16 of 29
©Retrotec Inc. 2012
If you choose to use equations relying on peak mass flow rate to calculate peak pressure and minimum
leakage required to relieve the peak pressure, entering smaller peak flow rates to override default
values may result in under-estimating minimum venting area required. Such an under-estimation would
lead to over-pressurization if a smaller than necessary vent is installed.
2.4 Choose enclosure leakage standard for calculating max hold time
2.5 Choose agent discharge model used in calculations
Select which type of fire suppression system discharge model will be assumed for calculation of the
maximum leakage for the specified hold time.
There are two options, defined according to how the extinguishing agent behaves after a discharge in
the enclosure:
“Descending Interface “– Agent is discharged at near-ceiling level into the enclosure. An ‘interface’ with
a constant concentration (known as the Initial Concentration) descends from the discharge level as gas
leaves the enclosure through leaks. The time it takes for this ‘interface’ to reach the Minimum
protected height is defined as the “hold time”.