The role of a special inspector for smoke control systems

Engineered Systems, Nov, 2004 by John Clark

just how special is this special inspector, anyway? When does he become involved? What kind of tests and reports are produced, and how does this inspection relate to inspections by code officials? Could I be a special inspector? As with any element of life safety, the answers are important--and that's not just blowing smoke.

Smoke control systems are required by building codes for high-rise building stairwells, zone smoke pressurized systems in hospitals, secure inmate facilities, floor-by-floor isolation in tall buildings, atriums, underground buildings, transit tunnels, and covered shopping malls. The systems may be pressurized systems or exhaust systems, and often contain both types.

The goal of these systems is to provide a smoke-free environment for occupants to safely evacuate or relocate to a smoke-free area. The facility with smoke control is also required to be "fire" alarmed and fully sprinklered. International Building Code (IBC) 2000, Section 909.3, requires that smoke control systems be subject to special inspections and testing to verify, the design and operation of the installed system. The special inspections duties and tasks are similar to commissioning.

THE SPECIAL INSPECTOR

The IBC 2000 909.3 and 1704.14 describes the duties and the qualifications for a special inspector. The key point is for the special inspector, individual, or agency to have the specialized knowledge of multidiscipline design comprised of ducted air, fire alarms, and fire sprinklers. The special inspector is an expert that assists the projects' team to verify a working code compliant system. The special inspector should be a licensed professional engineer with fire protection (sprinkler) design experience and the ability to manage the testing and balancing of the installed equipment. The project team is composed of the client, the designer, the various local code officials, the installing contractors, and the insurance underwriters. The special inspector should not design the system or replace the inspections of the various code officials during design and construction.

THE SYSTEMS

A smoke control system is an air-ducted system with fans, dampers, and the appropriate controls. The alarm and activation systems are the fire alarm and water flow in the fire sprinklers. Building security systems are used to alert security personnel and the fire department.

The systems are powered by normal and emergency power. Communication between the systems is by a fan-damper control interface, sprinkler alarm interface, and building security interface.

The following is a list of the typical system parts:

* Fans--supply and/or exhaust;

* Airflow paths through ductwork, dampers, louvers, intake/exhaust hoods, and doors;

* Fire command control panel;

* Sprinkler zones and flow switches;

* Fire alarm zones and detection types; and

* Security system calling, messages, and door lock control.

DESIGN REVIEW

The special inspector shall review the system design relative to the code requirements, discussing system design method with the authority having jurisdiction (AHJ) and the client. The design engineer should provide the calculations for cfm capacity at an early stage of the project.

During the review or discussion, a decision should be made relative to which power, alarm, and control systems must be installed in conduit, and which can he in plenum-rated cable.

The physical barrier zones, the fire alarm zones, and the sprinkler zones must be coordinated to all reflect the same coverage.

CONSTRUCTION PHASE OBSERVATION

A meeting should be scheduled early in the construction to communicate to the various subcontractors the expectations for their involvements in the smoke control system. An important message to the electrical subcontractor is to have the smoke control components wired up early for normal and emergency power. Coordinate a construction schedule with the general contractor.

PRETESTING

The purpose of this phase is to avoid surprises at the time of acceptance testing. Acceptance testing often occurs close to the sign-off date for occupancy. Many other client tasks depend on this occupancy date. Therefore, pretest and complete the acceptance list as soon as possible. A duct leakage pressure test at 1.5 times the designed pressure should be done using duct caps before grilles, registers, and diffusers are installed. Review the fan shop drawings for the required fan temperature ratings and the 1.5 times number of required drive belts with a minimum of two drive belts. Have the electrical contractor check the phase wiring between normal and emergency power. This is important to prevent fans from operating backward under emergency power. Verify that the security system that normally locks doors unlocks them when the smoke control system is activated. Also, verify lock operation on emergency power.

TEAM COMMUNICATION

The team should receive a copy of an event/action matrix as shown as a simple example on Figure 1. This matrix is based on the system design and AHI acceptance.