Retrotec FanTestic Integrity (ISO) - Manual (Page 44)

rev-2014-10-27
Page 44 of 50
©Retrotec Inc. 2012
The summary details the predicted peak pressure, the required minimum leakage to keep the pressure
under the specified enclosure pressure limit, and any additional vent area that will be required over
what is being assumed to provide the leakage for peak pressure relief (vent only or enclosure and vent).
The summary includes the following for each

Peak pressure [Pa]
The peak pressure that the enclosure is predicted to develop during the hold time, based
on the leakage being used for positive pressure relief.

“Leak to Volume ratio” (LVR
pos
, LVR
neg
) [sq in/1000 cu ft or cm 2 /m 3 ]
Used in the FSSA (and FIA for halocarbon) equations, peak pressure development during
hold time is a direct function of the Leak to Volume ratio. The Leak to Volume ratio
indicates how much leakage there is for a given unit of volume.

“Leakage area of enclosure” [sq in or cm 2 ]
The leakage area of the enclosure alone, with the result extrapolated to a pressure of 125
Pa.

“Leakage area of vent only” [sq in or cm 2 ]
The leakage area of the PRV alone, with the result extrapolated to a pressure of 125 Pa.

“…… used for positive/negative pressure relief” [sq in or cm 2 ]
Lists the leakage area the user has chosen to be used for pressure relief, calculated based
on the values in the venting datasets and the Total Enclosure leakage. It is used for the
purpose of calculating Peak Pressure during hold time of the fire suppression system. This
number is calculated based on the selection in the “For pressure relief use leakage area of”
dropdown menu (refer to section 4.3).
There can be a different leakage area used for the positive and negative direction since
different agents have different pressure release characteristics. Generally, Halocarbon
gases create a large negative Peak Pressure with smaller amount of positive Peak Pressure,
whereas Inert gases usually create large Peak Pressure only in the positive direction.

“Minimum leakage to relieve positive/negative pressure” [sq in or cm 2 ]
The smallest leakage area that will allow the peak pressure to stay under the specified
enclosure pressure limit and maintain the structural integrity of the enclosure during hold
time.

“Additional vent area needed” [sq in or cm 2 ]
The Additional vent area needed is the calculated amount of leakage that needs to be
provided, that does not currently exist based on the current settings. 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.
The additional vent area needed is calculated by subtracting the “… area used for pressure
relief” value from the “Minimum leakage to relieve pressure” value.