Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 9 - Fire Protection Systems
Section 909 - SMOKE CONTROL SYSTEMS
Subsection 909.6 - Pressurization method
Current through Register 1531, September 27, 2024
The primary mechanical means of controlling smoke shall be by pressure differences across smoke barriers. Maintenance of a tenable environment is not required in the smoke control zone of fire origin. [F]
909.6.1 Minimum pressure difference. The minimum pressure difference across a smoke barrier shall be 0.05-inch water gage (0.0124 kPa) in fully sprinklered buildings. [F]
In buildings permitted to be other than fully sprinklered, the smoke control system shall be designed to achieve pressure differences at least two times the maximum calculated pressure difference produced by the design fire.
909.6.2 Maximum pressure difference. The maximum air pressure difference across a smoke barrier shall be determined by required door-opening or closing forces. The actual force required to open exit doors when the system is in the smoke control mode shall be in accordance with Section 1008.1.2. Opening and closing forces for other doors shall be determined by standard engineering methods for the resolution of forces and reactions. The calculated force to set a side-hinged, swinging door in motion shall be determined by: [F]
F = Fdc + K(WA[DELTA]P)/2(W- d) | (Equation 9-1) |
where:
A = Door area, square feet (m2).
d = Distance from door handle to latch edge of door, feet (m).
F = Total door opening force, pounds (N).
Fdc= Force required to overcome closing device, pounds (N).
K = Coefficient 5.2 (1.0).
W = Door width, feet (m).
[Delta]P = Design pressure difference, inches of water (Pa).