If it is desired to use the second option in 714.4.4 for these
penetrations, the combined 50 cfm of air leakage through all
penetrations within a 100-square-foot area, then the cfm per square
foot value for each penetration must first be converted to cfm before
adding them all together. To convert cfm per square foot to cfm,
multiply the cfm per square foot L-rating value by the size of the
non fire-stopped opening, using units of square feet for the opening
size. After that conversion, the cfm leakage through all the nearby
penetrations can be added together to ascertain if the total leakage
is within the allowed 50 cfm per 100 square feet.
MOVEMENT RATING
During/ after a major earthquake, there is always a risk of a fire
breakout due to the damaged gas lines, electrical systems, etc.
Historical records show that small fires are often initiated by
earthquakes, and these sometimes grow into large destructive fires
causing loss of life and severe damage to property.
Inadequate supply of reticulated water is the largest single reason
for post-earthquake fire damage. This results mainly from damage
to the underground pipe distribution network, but also much other
active fire protection related components. Of the thirteen events
shown in the Table below, only one appears to have no major
damage to water supply systems. This is a major area of concern
for designers and providers of infrastructure.