Retrotec FanTestic Integrity (ISO) - Manual (Page 40)

rev-2014-10-27
Page 40 of 50
©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.
4.2 Enter air leakage data used to determine leakage area of PRV
When “no pressure relief vent” is chosen in the “Pressure relief vent (PRV) type” drop down, venting
area to relieve positive and negative peak pressure is calculated using “enclosure leaks only “ which is
displayed in the “Leakage area for enclosure” data box. The “Leakage area for enclosure” is the leakage
taken from the Total Enclosure Leakage section extrapolated to a standard reference condition of 125
Pa which is representative of conditions where most of the peak pressure will be relieved. In this case,
the venting datasets are not used.
When any of the other PRV types tare chosen, both venting datasets are used, the “Venting datasets
express leakage area of:” drop down is used to indicate what was measured (or estimated) in the
datasets.
When any of the PRV types that provide venting in both directions (for positive and negative pressure)
are chosen, both venting datasets are used.
If the “Venting datasets express leakage area of:” drop down shows “enclosure and vent”, datasets
contain data which resulted from measuring or entering an estimate of the leakage area of the
enclosure and vent combined. For measuring the positive venting dataset, the enclosure would have
been set up in a condition where dampers were fixed in the position they would assume under +125 Pa,
and for the negative venting dataset, the enclosure would have been set up in a condition where
dampers were fixed in the position they would assume under -125 Pa.