Planning A Fire Detection System; Detector Application - Siemens FC2025 Manual

4

Planning a Fire Detection System

When planning a fire detection system, select a detector based on the type of fires expected.
Consider the type and quantity of fuel, possible ignition sources, ranges of ambient conditions,
and the value of the property to be protected.
In general, heat detectors have the lowest cost and false alarm rate, but are the slowest to
respond. Since the heat generated by small fires tends to dissipate rapidly, heat detectors are
best used to protect confined spaces, or directly over hazards where flaming fires can be
expected. Usually they are installed on a grid pattern at their recommended spacing distances
or at reduced spacing for faster response. The operating temperature of a heat detector
should be at least 25°F above the maximum expected ambient temperature in the area
protected.
Smoke detectors cost more than heat detectors, but respond faster to fires. They are better
suited to protect large open spaces than heat detectors because smoke does not dissipate as
rapidly as heat does in the same size space. Smoke detectors are either installed according to
prevailing air current conditions or on a grid layout.
Photoelectric smoke detectors are best used in places where wire insulation or other
smoldering fires can be expected.
NFPA Standard 72 Chapter 5 has more specific information on the installation of the various
types of detectors.

Detector Application

4.1
In view of the problems that can be expected with the misapplication and location of detection
devices aboard a ship, the following guidelines are recommended when designing a system.
The table below list situation where smoke detectors should be avoided.
Moisture:
Salt water spray
Corrosive atmospheres
Excessive tobacco
smoke
Combusting Products and Fumes:
Cooking equipment
Ovens
Dryers
Exhaust hoods
Diesel trucks
Siemens Industry, Inc.
Building Technologies Division
Steam tables Heat treating
Humid outside air Dust or lint
Humidifiers Pneumatic transport
Live Steam Slop sinks, Showers
Metal cutting Chemical Fumes
Machining Cleaning fluids
Paint spray Gasoline forklifts
Curing Welding and brazing
Engine exhaust Dust accumulation
FS20 Marine Fire Detection Control Panel
Sawing, drilling and grinding
Water spray
Engines not vented outside
Heating element
Improper exhaust systems
Incomplete combustion
Locomotives
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