Fireground Support Operations (1st Edition)
Chapter 11 - Controlling Building Systems
Test Review
NOTICE: STORY-BASED ENTRIES/DISCUSSIONSARE not included in notes
§ Climate control systems range from small window-mounted units to huge commercial untis.
§ In general, the smaller the HVAC unit, the smaller the risk to firefighters.
§ HVAC ducts can be used to aid in expelling smoke from a building.
§ Many HVAC ducts have automatic-closing dampers (for fire conditions).
§ Window-mounted air conditioners are sometimes supported only by flimsy wood or metal platforms that may fail in a fire.
§ Defective worn-out HVAC belts and bearings on drive shafts of old HVAC units precipitate many "odors of smoke from ducts" calls.
§ Without lateral support when a rooftop HVAC unit collapses the roof, sidewalls can collapse.
§ An "In/Out" collapse occurs when sidewalls of different floors collapse, one inward, one outward, in a V-shape horizontally, out from the building.
§ ssSmall gas-fired furnaces can usually be controlled by shutting down the fuel at the gas meter.
§ Electrical heaters & HVAC systems can usually be controlled by shutting off electrical service at the main panel.
§ Many electrical heaters can be controlled by unplugging them.
§ HVAC systems can sometimes be used to help ventilate large building, so they should not be arbitrarily shut down.
§ HVAC system controls should be operated by an engineer, not firefighters.
§ Domestic lighting is defined as that normally used for interior/exterior illumination on day-to-day basis.
§ Emergency lighting is defined as that used to illuminate exit corridors and means of egress when domestic lighting fails.
§ All lighting units are ignition sources unless they are intrinsically safe.
§ Most emergency lighting activates automatically when domestic lighting fails (battery- or generator-operated).
§ Wet-cell batteries used for emergency lighting can cause acid burns if the electrolyte solution contacts skin.
§ Firefighters should look away from main electrical switches as they open them.
§ Shutting down emergency generators may also disable fire pumps and other emergency systems (done only on orders from IC).
§ The most common conveyance systems are elevators and escalators.
§ Sprinklers protecting escalators must be well supplied with water.
§ Preventing fire spread through escalator openings is difficult unless sprinklered or protected by automatic fire shutters.
§ One of the functions of "Lobby Control" is to bring all elevators to ground level and lock them there.
§ Building occupants are not allowed to use elevators as a means of egress.
§ Elevators may not be used by firefighters to access the fire floor or above until officer in charge of fire floor declares it safe to do so.
§ Some departments allow use of blind-shaft elevators to travel above the fire floor, then walk down to the fire floor.
§ Smoke detection systems range from individual battery-operated detectors to hard-wired systems with multiple interconnected detectors.
§ Smoke detectors can be actuated by products of combustion generated early in the growth stage.
§ Photoelectric smoke detectors (AKA visible products of combustion detectors) use photoelectric cells and a light source.
§ Beam application type photoelectric detectors emit a beam horizontally across the ceiling of a compartment to a photoelectric cell on the other side of the room (holds an electromagnetic switch open).
§ Ionization detectors use tiny radioactive beta sources (usually americium) to ionize air molecules entering the smoke detector chamber (smoke cause drop in electrical current, setting off detector).
§ The major hazard with smoke detection systems is false alarms.
§ Fixed-temperature thermostats are a type of heat detection system which relies on tiny heat sensors (called thermostats).
§ Fixed-temperature thermostats are actuated by a bimetallic contact bending from heat or by fusible element melting from heat (both cause electrical contacts to meet and set off alarm).
§ Rate-of-rise detectors can set off at a much lower temperature than fixed-temperature detectors.
§ The greatest hazard with heat detections systems is unreliability.
§ Flame detectors (AKA light detectors) are among the most sensitive fire detection systems and consist of UV detectors and IR detectors, or combinations of both.
§ Flame detectors operate on a line of sight basis (blocked by opaque objects).
§ IR detectors are designed to require a flickering motion of light (reducing false alarms).
§ Flame detectors are susceptible to false alarms from sunlight, welding, mercury vapor lamps, and other bright light sources.
§ Fewer false alarms occur in systems that have IR and UV detectors covering the same area.
§ In wet sprinkler systems, water fills the entire system from water source to each sprinkler head and are installed where freezing is NOT likely.
§ Wet sprinkler systems may be filled with antifreeze (ethylene glycol, propylene glycol, or glycerine).
§ In dry sprinkler systems, the distribution piping is filled with air under pressure.
§ Deluge systems are used to protect specialized occupancies.
§ Hazards of sprinkler systems are that they can keep smoke from getting hot enough to activate fusible links on smoke vents, can prevent heat from escaping vertically, can scold firefighters, cause icy conditions, and increase load on the structure from water.
§ If an OS&Y valve is shut down to a sprinkler system, a firefighter with radio should stay at the valve in case it must be turned back on.
§ Alarm bells or alerting devices of heat/flame detection systems should be silenced during investigation.
§ Alarm systems should not be reset (only silenced) until source is found and presents no hazard.
§ Halon systems have an "abort" switch in conjunction with the manual activation handle.
§ In most cases, an OS&Y or PIV valve is used to control sprinkler system water supplies (some are shut down by stopping fire pump).
§ Shutting down a sprinkler system must only be done on orders from IC.
§ Most fire departments do not allow personnel to restore dry pipe systems to service.
§ Some departments set up an electronic heat/smoke detector for rekindles prior to leaving the scene.
§ In dry pipe standpipes systems, water supply is controlled by disconnecting supply hose from FDC.
§ In wet pipe standpipe systems, water supply is controlled by shutting off fire pump or main water supply valve.
§ In standpipe systems that share water supply with sprinkler systems, water supply must be shut down at the OS&Y or PIV valve.
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