Fire Alarm Detectors (2)

Combined Smoke and Heat Detectors

Combine smoke and heat detector shall comprise of two chambers. One chamber containing the photoelectric smoke detector and the other shall contain the heat detector. The smoke detector shall utilize a horizontal optical bench construction which houses the detector and the optical sensor.

Fire Alarm Detectors (1)

1.     Photoelectric Detectors

Photoelectric smoke detectors use light and how it is reflected to detect smoke. Normally light is projected into a smoke sensing chamber inside the detector assembly. The light hits a black background of the chamber and is absorbed. When enough smoke enters the chamber it reflects the light on to a sensor inside the chamber. This causes the sensor to indicate an alarm. Photoelectric detectors are suitable for most applications giving the fastest response to slow burning fires - the most common start to fire events. Use of photoelectric detectors is highly recommended to provide coverage for escape routes due to their superior ability to detect optically dense smoke that would easily obstruct the use of escape routes.

What CCTV is?

What does CCTV stand for? CCTV means  Closed Circuit Television, which is a visual surveillance technology designed for monitoring a variety of environments and activities. CCTV systems are used in applications such as monitoring public areas for violent actions, vandalism, theft, and unlawful entry, both indoors and out. CCTV recordings are used to obtain and provide evidence for criminal and other investigations, they are sometimes disclosed to the media in the hopes of gaining information about images of a suspect or suspects caught in or near a crime scene.

B. ADDRESSABLE OR “ INTELLIGENT ” FIRE ALARM SYSTEM (Cont.)

Addressable Fire Alarm Panel

Allows security staff to determine exactly from where the alarm is coming without searching the entire building. Being intelligent implies that each detector can “think” independently, determining when and where there is a fire. The panel provides the information about the sensor’s performance, event log, indication when the sensor needs servicing.
Unlike conventional alarm methods, these systems monitor and control the capabilities of each alarm initiating and signaling device through microprocessors and system software.

A. CONVENTIONAL FIRE ALARM SYSTEM

 A.K.A  “point wired” fire alarm system. One or more circuits are routed through the protected spaces or building. Along each circuit one or more detection devices are placed
System is often the natural choice for smaller system. Conventional type monitors the condition of each circuit by sending a small current through the wire. Should a fault occur, such as due to wire break, this current can not proceed and is registered as “trouble” condition.

Fundemantal of Fire Alarm System

In order to undertake the process of designing a fire Alarm and Detection system for a building it is essentially  necessary to have a full understanding, if not, the fundamentals of the relevant design standards, codes, ordinances, the legal framework surrounding building safety legislation and a sound working knowledge of product application theory. The following system design process is intended to give a reasonable overview of all the areas of knowledge required for the successful design of a fire alarm system. Due to the complex nature of legislation and design standards relating to fire alarm system design, this chapter will somehow serve as  a very useful source of background information to which further application specific detailed information can be added from other sources as required.

            Basically, a fire is a chemical reaction in which a carbon based material (fuel), mixes with oxygen (usually as a component of air), and is heated to a point where flammable vapors are produced. These vapors can then come in contact with something that is hot enough to cause vapor ignition, and a resulting fire. In simple terms, something that can be burn touches something that is hot, and a fire is produced.