NFPA 90A Section 4.3.3

NFPA 90A / NEC Article 725.3

Duct smoke detector shutdown must be hardwired directly to the HVAC equipment disconnect, independent of BAS software. A software-only alarm response means the system continues running during a smoke event if the BAS fails or the alarm is dismissed. NFPA 90A requires hardwired shutdown with audio/visual alarm at the control display panel.

NFPA 90A / NEC Article 725.3 / IBC 907.3

HVAC shutdown and smoke damper control on fire alarm must be accomplished through hardwired connections, not through BAS software commands alone. BAS software can supplement but not replace hardwired interlocks. If the BAS network fails, loses power, or has a software error, the life-safety interlock would not function. NFPA 90A requires direct hardwired shutdown independent of any programmable system.

NFPA 90A Section 4.3.10.3

Flexible duct is not permitted to penetrate fire-rated wall or floor assemblies. Only rigid metal duct with proper fire dampers may pass through rated barriers. Flex duct will burn through and compromise the fire barrier.

NFPA 92 / IBC Section 909

Smoke control dampers must never be overridden from the BAS workstation, regardless of whether the fire alarm is in test mode. Smoke control overrides can only be performed at the fire alarm panel or the firefighter smoke control panel (FSCP) per NFPA 92 and IBC 909. BAS overrides of life-safety devices are a serious code violation that compromises building occupant safety.

NFPA 92 Section 4.4.2 / IBC 1010.1.3

This passes code. NFPA 92 Section 4.4.2 requires stairwell pressurization to achieve two performance criteria: (1) a minimum pressure differential of 0.05 inches w.c. across closed doors (this system achieves 0.08), and (2) sufficient airflow through open doors to prevent smoke migration. The 200 fpm velocity through open doorways is commonly accepted as the minimum to prevent smoke infiltration. IBC 1010.1.3 limits door-opening force to 30 lbf — the measured 20-28 lbf is within limits. The system achieves the delicate balance between maintaining enough pressure to exclude smoke while not overpressurizing to the point where doors cannot be opened.

NFPA 92 Section 4.4.2.1

NFPA 92 Section 4.4.2.1 requires multiple injection points for stairwells exceeding 8 stories in height. A single injection point creates excessive pressure at the top and insufficient pressure at the bottom, resulting in inability to open doors at upper floors and inadequate pressurization at lower floors. Multiple injection points every 2-3 floors are required for tall stairwells.