The role of a special inspector for smoke control systems

Engineered Systems, Nov, 2004 by John Clark

[FIGURE 1 OMITTED]

ACCEPTANCE TESTING

During the pretest, the system can be activated by puffer smoke or a magnet to simulate a fire alarm. The sprinkler flow switch can be manually tripped to simulate water flow. However, during acceptance testing, the pass/fail criteria is pressure differentials across the zone or door barriers, door pull forces that do not exceed 30 pounds, a copy of the TAB report to verify the cfm, and operational verification of all the dampers. However, it is often requested to provide a "smoke show" to indicate that the smoke is controlled. Provide a hot rising thermal plume using a heat source and chemical smoke. In small systems, real smoke can be generated in a galvanized trashcan with a cover that controls and stops the smoke. Burning of wet cardboard works well in this trashcan and simulates a small fire.

THE REPORT AND CERTIFICATION

The report, which is written by the special inspector and signed by the design engineer, confirms that the system meets the design intent.

The report should document the design intent, the system description, schematic diagrams, the measured pressure test values, the airflow TAB report, the pass/fail criteria, pretest memos, installation equipment photographs, and the conclusion. Copies of the report should be filed with the code authority, the client, the design engineer, the responsible contractor, and the special inspector.

WHAT GOES WRONG?

The following is a list of corm-non problems that occur during pretest and sometimes appear at the acceptance test.

* The fan produces too much or too little cfm and/or pressure;

* The barriers are not constructed reasonably airtight;

* Installation screws block damper operations;

* Fire alarm system software is not correctly programmed;

* The smoke detectors are too close to the supply diffusers, and the real smoke will not alarm the system; and

* Fan motors overheat and will not restart.

SUMMARY

A smoke control system is an integrated multidisciplinary system. Its successful operation depends on the team's understanding the interrelationship of the components. Each contractor and code official can install and observe his piece of the smoke control system. However, the special inspector is the commissioning agent who verifies that the system is designed correctly and does operate to the design intent.

The special inspector is required by code, is contracted directly with the client, is involved early in the project, and checks and tests all through the project to avoid a surprise or delay at the point of occupancy sign-off.

Figure 1. Typical event/action matrix based on the
system design and AHJ acceptance.

                                ACTION

                   Status to   Zone fire   Sprinkler
EVENT              security      alarm     flow alarm

Normal operation    Normal        Off         Off
Sprinkler flow       Alarm        Off          On
Space fire alarm     Alarm        On          Off
Tenants' AHU         Alarm        Off         Off

                                ACTION

                   Stairwell   Skeakers     Tenants'
EVENT                 fan       strobes       AHU

Normal operation      Off         Off         Off
Sprinkler flow        On          On          Off
Space fire alarm      On          On          Off
Tenants' AHU          On          On          Off