Instrumentation 2: Alarm Systems Overview

Course Information

• Course Code: ECME-214
• Course Title: Instrumentation 2 & Monitoring Systems
• School: Engineering Technology & Applied Science (SETAS)
• Week: 2
• Topic: Alarm System Components and Operation

Objectives

• Study of alarm systems and their components, including:
  • Pull Stations
  • Heat Detectors
  • Smoke Detectors
  • Bells
  • Strobes
  • Speakers
  • Thumpers
  • Ancillary relay circuits
  • Annunciators

Purpose of Fire Alarm Systems

• Primary purpose: Protect lives
• Secondary purpose: Protect property and initiate fire fighting
• Best way to fight fire: Prevent it by avoiding circumstances that start fires

Types of Systems

• Passive systems:
  • Include building components and design choices
  • Mandated by building and fire safety codes, including:
    • Fire walls
    • Separation between hazardous locations
    • Fire resistance ratings
    • Flame spread ratings with smoke control and fire stops
  • Approved exit systems for emergency egress from a building are necessary.
  • High-rise buildings face challenges due to stack effect from wind and temperature differences, which can cause stairwells and corridors to fill with smoke during fires

Main Components of Fire Alarm Systems

• 3 main components:
  • Manual and automatic initiating and detection devices
  • Audible alarm signal devices
  • Central control unit to process the incoming information

Detection/Signaling Systems (continued)

• Detection devices (pull stations, heat, flame, and smoke detectors) detect fires and send a signal to the Fire Alarm Control Panel (FACP).
• Visual signals include strobe lights.
• Audible signals include bells, horns, sirens, and speakers.

Main Controller

• Brains of the system
• Provides power to the system
• Monitors inputs and controls outputs through circuits
• Performs other functions as required by the appropriate code

Elements of a Control Panel

• Requires two power sources (electrical outlet and battery backup).
• Inputs:
  • Initiating Device: Originates transmission of a change of state condition (e.g., smoke detector).
  • Initiating Device Circuit (IDC): Automatic or manual initiating devices are connected, where the signal received does not identify the individual device operated.
• Outputs:
  • Notification Appliance: A component (bell, horn, speaker, light, text display) that provides an audible, tactile, or visual output or any combination.
  • Notification Appliance Circuit: The circuit directly connected to the notification appliance.

The Basic System

• Diagram of the components (main controller, initiating devices, and notification appliances).

Initiating Devices (Manual Fire Alarm Stations)

• Manually-operated devices to initiate an alarm.
• Single action stations require a single operation (pulling down).
• Dual action stations require two distinct operations (setup and activate).

Fire Lite BG-12

• Dual action model with screw terminal connections and a hex lock reset.

Fire Detection Principles

• Automatic Detectors: Detect smoke, heat, or flame, and are categorized as spot type.

Smoke Detectors

• Photoelectric: Detects light scattering from smoke particles.
• Ionization: Detects the ions created when smoke particles enter the ionization chamber.
• Sensitivity differences: Photoelectric detectors are better at detecting light smoke, while ionization detectors detect early-stage smoke.

Heat Detectors

• Detect fixed temperatures like 57°C or 90°C or rapid temperature changes (rate-of-rise).
• Combination units are also available.

Flame Detectors

• Used in high-hazard applications for rapid fire detection.
• Must not be blocked by objects.
• Infrared detectors have capabilities to detect radiation from walls.
• Detection cone/viewing angle similar to the human eye.

Beam Detectors

• Photoelectric light obscuration.
• Light source and photosensitive sensor.
• Smoke obstructing the light path reduces the light reaching the receiving sensor.
• Alarm condition triggers when preset criteria are met.

Air Sampling/Duct Detectors

• Piping/tubing connects the detector to the area to be monitored.
• Aspirating fan draws air.
• Air is analyzed for fire products.

Notification Appliances Types

• Audible (horns, bells, sounders, sirens, chimes, speakers)
• Visual (strobes)
• Physical (bed shakers)
• Olfactory (smell)
• Thumper (alerts the blind)

Building Notification/Notification Appliances

• Fire alarm system components (bell, horn, speaker, light, or text display) provide audible, tactile, or visible outputs.
• Audible notification appliances alert by the sense of hearing.
• Visible notification appliances alert by the sense of sight

Audible devices

• Bells: Distinctive sound used in fire alarms or sprinkler systems.
• Horns: Loud, often used in high-noise environments.
• Sounders: Electronic or mechanical devices capable of different tones.
• Chimes: Soft-toned devices used in areas where loud noises are disruptive.
• Sirens: Extremely loud, typically used outdoors or heavy industry.
• Speakers: Audible output used with evacuation messages.

Visual Signaling Appliances

• Visual signaling appliances are used in high-noise environments, areas occupied by hearing-impaired individuals, or where audible devices are not desired.

Annunciators

• Fire alarm notification appliance that displays system modes, status, and alarms.
• Addressable fire alarm panels display configuration information in a floor plan.

Types of Fire Alarm Control Panels (FACP)

• Conventional (hard-wired): Simplest design with a single circuit board containing power, control, initiation, and notification circuitry.
• Programmable: Components are selected to meet specific customer needs; circuits are programmable.
• Addressable (multiplexed): Each device has a unique address and data transmits along a signaling line circuit (SLC) loop.
• Intelligent (analog data transfer): Addressable, detailed analog data is processed and sensitivity data can be provided.

Wiring Requirements

• Power-limited and nonpower-limited circuits must be separated in the cabinet.
• Special wiring considerations include:
  • Maximum of two wires are joined together.
  • Wires are not looped around terminal screws. Wires must be cut and placed under screw.
  • End-of-line (EOL) resistors must be in separate boxes for more than one notification device.
• Correct and incorrect wiring methods are visually demonstrated for two-wire detectors.

Terminology

• List of terms and acronyms related to fire alarm systems (e.g., FACP, ULC, NFPA).

ULC Standards

• Detailed list of ULC standards related to fire alarm systems.