Testing smoke management systems
Codes and standards are created to standardize the way buildings are designed and constructed to help ensure a safe built environment. Codes tell us where to install something, and the standards typically tell us how. But the ultimate question is: What is considered safe, and why? A great fire system design, if not properly installed, inspected, and tested—or not properly maintained—is a life safety concern that cannot be overlooked.
When considering fire systems, there are several different systems that can fall under this general umbrella. The most common are automatic sprinkler systems, which are found in most nearly all commercial buildings as well as some residential buildings as a result of recent code changes. Other systems to be considered are the fire alarm and detection systems, including initiation devices (e.g., smoke and heat detectors) and notification appliances (e.g., horns, strobes, speakers). Also included are smoke management systems, which are typically composed of stairwell pressurization systems and smoke removal systems within high-rise buildings, atria smoke exhaust, and large open areas provided with smoke management.
Over the course of the past 30 years, smoke management systems have been an integral part of high-rise building design, particularly in Clark County, Nev., where Las Vegas is located. This is due in large part to the MGM fire that took place in 1980 and the designers and authorities having jurisdiction (AHJs) who have been working together to protect the millions of visitors that have been visiting Las Vegas ever since.
Codes and standards
The International Building Code (IBC) is the predominant building construction code in the United States and is spreading throughout the world. This document has been developed over multiple decades as a design guide for building construction. Chapter 9 of the IBC is dedicated to fire protection systems and provides the criteria for where these systems must be installed and minimum requirements for system design and installation.
Section 909 of this chapter outlines the requirements for smoke control systems. This section provides design, installation, and acceptance testing requirements in addition to outlining specific NFPA standards to which the smoke control systems are required to be designed. Specifically, NFPA 92: Standard for Smoke Control Systems is referenced. Knowing the where and how of these systems is critical; so is understanding their interconnection and how they must be tested and maintained.
Inspections and testing
Fire alarm systems often are used to control and monitor smoke management systems. There is a common misconception that the special inspector for smoke control systems is inspecting and testing the associated fire alarm system, as required by NFPA 72: National Fire Alarm and Signaling Code. The special inspector is only confirming the proper function of the fire alarm system as it relates to its interconnection with smoke control systems. NFPA has other requirements for fire alarm system testing beyond what is required for smoke control systems. Therefore, proper system control, monitoring, and sequence output by the fire alarm system are what will be confirmed by the special inspector for smoke control systems. When performing inspections and testing of smoke management systems as the special inspector, there is a standard sequence of events that is consistent for all projects. Following is an outline of these 10 events:
Approved design documentation procurement and review
Test documentation preparation
Duct inspections and testing
System fault testing
Final system fault testing
Emergency/secondary power testing
Special inspections activity reporting.
These activities are intended to occur once final installation is accomplished and system pretesting is completed by the responsible contractors. All inspections and testing activities are typically achieved with a standard team consisting of the special inspectors and contractor representatives responsible for the installation and pretesting of the smoke management system equipment being tested.
It is important to note that the special inspector is there to perform inspection and testing to approved design documentation and generally accepted engineering practices. It is not the responsibility of the special inspector to design, redesign, and/or dictate the design requirements of the associated systems. The special inspector is to execute his or her inspections and testing in accordance with the applicable code of record, approved design documentation, and generally accepted engineering practice.
Ten steps to successful testing
Follow these 10 steps for successful testing of smoke management systems:
1. Approved design documentation procurement and review
As a special inspector of smoke management systems, the first step is to gather the approved design documentation, which should include drawings, reports, rational analyses, control diagrams, equipment data sheets, and possibly specifications. This documentation should be thorough enough to provide a complete understanding of how the systems are designed and intended to function to produce necessary performance criteria. Additionally, the design documentation will provide direction on the means and methods in which the special inspections are to be performed to confirm proper construction and functionality of the subject smoke management systems. The design documents should show zone boundaries, equipment specific to the smoke control system, and a sequence of operations outlining how the system operates.
2. Test documentation preparation
After reviewing all pertinent documentation and information, the inspector can begin putting together the testing documentation, which typically consists of a testing plan as well as testing scenarios, outlining the cause and effect of various input/output functions of the systems. For example, the initiation of a smoke detector may cause a combination fire/smoke damper to close or open, supply fans to stop, exhaust fans to start, doors on magnetic hold-open devices to close, and the building notification appliances to activate, thereby notifying building occupants of a potential fire hazard and to exit the building appropriately.
By developing a testing plan in conjunction with scenarios, the special inspector can be sure that all elements of the systems will be tested in accordance with the design documents and in compliance with AHJ requirements. In addition, these documents provide a road map for anyone who would be doing the testing, either at initial approval stage or years down the road when trying to recommission the systems. The more complete this information is, the more prepared the special inspector and the more comfortable a building engineer is once the building is open and operational. Once complete, it is intended that this documentation be shared with all concerned parties working on the project (i.e., owner, general contractor, mechanical contractor, fire alarm contractor, etc.) and in some jurisdictions, this will be submitted to the AHJ for its acceptance.
3. Duct inspections and testing
There are several distinct stages to testing interconnected systems, and the process starts with ductwork inspections and testing. Per IBC Section 909.18.8.1, during erection of the ductwork and prior to concealment, testing is required to confirm duct leakage is within the allowable ranges. As the building is constructed, some of the first things to be installed are the fans and associated ductwork because they can both take up a large amount of space. Further, In accordance with IBC Section 909.10.2 (2012 edition):
“Duct materials and joints shall be capable of withstanding the probable temperatures and pressures to which they are exposed as determined in accordance with Section 909.10.1. Ducts shall be constructed and supported in accordance with the International Mechanical Code. Ducts shall be leak tested to 1.5 times the maximum design pressure in accordance with nationally accepted practices. Measured leakage shall not exceed 5% of design flow.”
The intent of leakage testing is to ensure that the amount of air designed to be exhausted from a space is actually able to be exhausted from that space, the amount of air required to be supplied may be provided, and that smoke does not leak out of the duct as it’s being transmitted from the smoke zone to the exterior of the building. In addition to leakage testing, ducts should be inspected to confirm anchoring to appropriate structures and that they are reasonably installed per design documentation. At this time, the special inspector should also confirm that the exhaust from smoke exhaust fans does not discharge to areas that will result in the reintroduction of smoke into the building. Ensuring that air is permitted to go to and from the smoke zone in alarm conditions lays the foundation of a functioning smoke management system. Identifying any ductwork issues at this time allows for repairs to be accomplished before shafts or ceilings are complete.
4. Field inspections
Field inspections occur throughout the entire special inspection process. This includes inspecting automatic sprinkler system zoning as it relates to smoke zone boundaries, equipment related to smoke management systems, and smoke control barriers for proper continuity. All equipment will be inspected to confirm it matches specified equipment and meets the requirements of associated design documentation and applicable codes and standards. Another key aspect of special inspections is field inspections of passive and active smoke management system barrier containment.
The IBC requires that all smoke zones be separated from one another by 1-hour fire-resistance rated smoke barriers, at a minimum. Any openings within those barriers are required to be protected, typically with an approved and listed door or damper. When inspecting doors, the inspector must review the rating to confirm it’s installed in accordance with the contract documents and its listing, as well as whether it’s provided with the necessary automatic or self-closing door mechanisms. Requiring either an automatic or self-closing mechanism on doors within a smoke zone boundary provides a means of ensuring that the integrity of the wall is maintained during a fire event.
Dampers also are inspected to confirm they are installed per their listing and manufacturer guidelines, are the proper device type, have the necessary associated smoke detection device, and to confirm the damper position upon loss of power or smoke control mode. Again, ensuring that the smoke zone boundary’s integrity is maintained is critical to minimizing the potential smoke and fire spread through a building. Exit enclosures have a slightly higher degree of safety based on their use as exits. The only penetrations that may occur in an exit enclosure are those that are associated with the use and operation of the exit enclosure. In other words, conduit, equipment, HVAC ductwork, piping, or other utilities cannot be within the exit enclosure unless it serves the exit enclosure. The special inspector should take note of any exit enclosures to confirm openings and penetrations comply with code.
5. System force faulting
This phase of testing is intended to confirm the provided system for monitoring is truly monitoring the true position/status of necessary smoke management system equipment, as required by IBC Section 909.12. This is regularly referred to as “force faulting” the system, which means the inspector is intentionally and manually manipulating system equipment opposite its required status to achieve proper system performance to confirm a fault status actually is provided. Force faulting is achieved through manipulation of equipment that is monitored, opposite its required position, per design documentation necessary to achieve system performance. This can include confirming that notification is provided with loss of power to equipment if a fan is running without belts. At this stage of testing, it is only verified that smoke management system fans provide a fault with loss of power. Final verification of proper equipment monitoring of fans and dampers occurs following verification that system performance is accomplished.
6. Sequence testing
Sequence testing of smoke management systems includes verification that properly zoned initiation devices, once activated, result in the proper configuration necessary to achieve the prescribed performance criteria. This includes confirmation of automatic activation (i.e., smoke detectors, water flow switches, etc.) and manual control of the system at the firefighter’s smoke control panel. Necessary equipment and system configurations are determined from design documentation and outlined in the prepared test scenarios. All initiating devices required to activate the smoke management systems will be tested to confirm proper functionality of the device. Fans, dampers, and sometimes doors will be confirmed to be in their proper sequence to achieve the design requirements. Special inspectors will verify each device in the field and confirm monitoring at the panel. Nonmonitored equipment (i.e., side-hinge man doors on hold-open devices, etc.) will be reviewed at this time to confirm proper operation and configuration of the equipment with system activation.
7. Performance verification
Smoke management system performance criteria, as determined by the engineer of record, are dictated by the method of smoke control utilized and should be documented in associated design documentation. For performance verification to occur, the status of construction is to be final condition to ensure all measured results are accurate and true and will reflect in the building when open. The prescribed performance criteria will be provided by approved design documentation which may include pressure differences, airflow, or exhaust rates. Code requires that testing activities be performed by qualified inspectors. As verification of the performance of smoke management systems necessitates the measurement of air movement and atmospheric conditions, inspectors/agencies certified for test and balance (i.e., Associated Air Balance Council, National Environmental Balancing Bureau, etc.) should be utilized for this aspect of inspection and testing. The design criteria will be used to determine where and how the measurements will be taken.
8. Final system fault testing
This phase of testing typically encompasses final confirmation of proper monitoring of smoke management fans’ operational status by the control system. As the majority of fans are belt driven and the operational status of fans is provided primarily through a current sensing devices, during this time a “belt-on/off” test is performed for all fans required to energize and operate for a smoke management system. This test is only to occur after conformation of the proper performance of a smoke management system has been determined. This test consists of removing the drive belts and operating the fan to verify this trouble condition is properly reported.
9. Emergency/secondary power testing
When all smoke management systems and associated equipment have been thoroughly inspected and tested, and performance criteria is met, necessary emergency/secondary power sources are verified to all necessary equipment. Typically, this verification is accomplished through the transfer of normal power sources to emergency/secondary sources via activation of the building shunt(s) or manual transfer to backup power sources. Once transferred, confirmation of proper power sources is accomplished by activation of all necessary smoke management systems, with proper operation being verified at the firefighter’s smoke control panel. It is assumed at this time, due to special inspector activities, a level of confidence in the system components and monitoring systems has been achieved and the inspector is relying on the appropriate control and monitoring systems to confirm proper operation. Typically, the largest operating zone will be placed in operation prior to transfer of power to verify the system reconfigures in the required timeframe. The largest zone typically places the largest load on the secondary power source.
10. Special inspections activity reporting
The IBC requires all testing activities to be recorded by the special inspector. Upon the completion of inspection and testing activities, the inspector will compile all associated data in a final report and typically submit this to the owner, at a minimum, and typically to the AHJ for review and acceptance. The intent is that this report be maintained on record to confirm the proper commissioning of the associated systems has occurred and to assist in the future acceptance of the associated systems due to regular recertification requirements or tenant improvements.
These activities are a general outline of typical necessary special inspection activities for confirming the proper construction and operation smoke management systems. Depending on the type of project and level of construction, some of the listed activities may not be applicable. Thorough and comprehensive inspections and testing of smoke management systems are intended to ensure a safer built environment for a building’s occupants.
Nicholas A. Moriarty is director of fire protection at JBA Consulting Engineers. Moriarty has nearly 10 years of experience in fire protection and life safety. He is experienced in hotel/casino, residential, correctional, and educational projects. Mark E. Mecham is senior engineer – fire protection at JBA Consulting Engineers. Mecham has experience in witnessing the verification of smoke control and fire alarm systems, and producing smoke control diagrams.