Toronto Fire Services Training Note - March 2019 - PDF

Fire Services Training Division Training Note FROM: Fire Chief EFFECTIVE DATE: March 25, 2019 FILE IN TFS TRAINING MANUAL UNDER: GROUP: 100 Firefighting Knowledge and Skills SECTION: 101 Buildings SUB-SECTION: 101.1 High Rise Buildings UNIT: 101.1.2 Heating, Ventilation and Air Conditioning TABLE OF...

Fire Services Training Division Training Note FROM: Fire Chief EFFECTIVE DATE: March 25, 2019 FILE IN TFS TRAINING MANUAL UNDER: GROUP: 100 Firefighting Knowledge and Skills SECTION: 101 Buildings SUB-SECTION: 101.1 High Rise Buildings UNIT: 101.1.2 Heating, Ventilation and Air Conditioning TABLE OF CONTENTS 1. INTRODUCTION.................................................................................................. 2 2. HEATING, VENTILATION AND AIR CONDITIONING (HVAC)........................... 2 3. HVAC AND FIRE.................................................................................................. 2 4. PRESSURIZED FLOORS AND STAIRWELLS.................................................... 2 5. HVAC CONSIDERATIONS.................................................................................. 2 Toronto Fire Services Training Division Training Note: 101.1.2 Date Prepared: March 2019 Page 1 of 3 1. INTRODUCTION Heating, Ventilation and Air Conditioning (HVAC) Systems are installed in buildings to circulate heated or cooled air, depending on the season, and to maintain a suitable mixture of fresh and recycled air throughout the building. There may be a conflict between HVAC and Fire Service Ventilation when dealing with fire conditions in a high-rise fire. This conflict may be compounded because of the size and complexity of the HVAC system and structure. 2. HEATING, VENTILATION AND AIR CONDITIONING (HVAC) High rise buildings depend on HVAC systems. High rise buildings are sealed in order to establish predictable, controllable interior air movement. Unfortunately, fire can easily interfere with the predictable nature of an HVAC system. 3. HVAC AND FIRE In a working high-rise fire or large building complex, continued operation of the HVAC System may aid or hinder fire attack and tactics. Smoke and heat detectors are required at different locations within the system to shut down specific zones or components, such as dampers and fans, if products of combustion or heat are detected in the distribution system. A fan shut down stops mechanical fresh air to the fire area. Fire dampers are similar to automatic fire doors which operate by fusible link connections. The fire damper’s primary goal is to stop fire spread. The fusible links are activated by either heat (due to fire) or mechanically (by manual control). Failure of components from direct exposure to fire, faulty installation or simple malfunctions can quickly complicate a fire scene. 4. PRESSURIZED FLOORS AND STAIRWELLS The Ontario Building Code requires many safeguards in HVAC systems to prevent or minimize smoke extension from the area of origin. The actions that occur because of the integration of fire alarm and HVAC systems vary but generally, when the alarm is activated, the ventilation system should shut down the ventilation system on the alarm floor. It should pressurize stairwells and firefighter elevator shafts until the fire alarm panel is reset. In buildings with pressurized stairwells, the ground level doors may open when the alarm is activated to relieve pressure. If the doors are not opened, over pressurization of the stairwell may result in difficulty opening stairwell access doors on individual floors. Some systems are capable of pressurization of up to 280 kPa (40 psi). Toronto Fire Services Training Division Training Note: 101.1.2 Date Prepared: March 2019 Page 2 of 3 5. HVAC CONSIDERATIONS The Incident Commander, as part of initial size-up and IAP development, must address the status of the HVAC system. Anticipation of smoke travel will be based on experience, building familiarization and the characteristics of the incident at hand. HVAC systems, because of their complexity, require qualified individuals to assess, troubleshoot and operate. A qualified operator should always confirm automatic operation of features and components. Firefighter teams can provide updates on smoke conditions as they move through the building. This information coupled with HVAC system knowledge and operations panel indicators will be of assistance to the HVAC operator and ultimately to the Ventilation Sector Officer. Toronto Fire Services Training Division Training Note: 101.1.2 Date Prepared: March 2019 Page 3 of 3