Page 326 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

Heat, smoke and fire gas detectors should be installed in a grid pattern at
their recommended spacing, or at reduced spacing for faster response.
---ใช้เพื่อการศึกษาเท่านั้น---
Each system should be engineered for the specific area being protected,
with due consideration given to ventilation characteristics.

งสมุด ศูนย์ฝกพาณิชย์นาวี
Detection systems for actuation of fire extinguishing systems should be
arranged using a cross-zone array. In a cross-zone array, no two adjacent
ionisation type detectors should be in the same detection circuit zone.
The first detector actuated should activate the fire alarm system, while the
actuation of a detector on an adjacent circuit should activate the fire
extinguishing system.

19.2.7 Fixed Combustible and Toxic Gas Detectors

These gas detectors are designed to sense the presence of combustible
or toxic gases to provide an early warning. They are used to provide
continuous monitoring of potentially hazardous areas to safeguard
against fire or explosion and for personnel protection from toxic gas leaks.
The operating principles of combustible and toxic gas detectors are
similar to those for the product of combustion-gas sensing fire detectors.
See also Sections 2.3 (Toxicity) and 2.4 (Gas Measurement).
Terminals that handle crude oil or products containing toxic components
ึ
should consider installing fixed gas detection and alarm equipment in
areas where personnel may be exposed. Consideration should be given
to placing sensors in locations where leaks or spills could occur, for
example loading arms, valve manifolds and transfer pumps, or where gas
could accumulate due to inadequate ventilation. Toxic gas detectors may
also be installed in the supply air intakes of pressurised control rooms
and inside non-pressurised control rooms.

19.2.8 Locating Fixed Combustible and Toxic Gas Detectors
General considerations in positioning combustible and toxic gas detectors
include the following:
Elevations depending on relative density of air and any potential gas
leakage.
งานห้อ Accessibility of detectors for calibration and maintenance.
Possible flow direction of leaking gas.

Proximity to potential hazards.

Sources of damage, such as water and vibration.

Manufacturer’s recommendations for sensors connected to analysers.

Fixed Combustible and Toxic Gas Analysers
19.2.9
Continuous analysers are typically permanently installed, electrically
operated devices for the continuous analysis of air samples for detecting
combustible and toxic gases, often using multiple sensors.

The analysers may be of the remote detection type in which individual
diffusion sensors are connected to the analysers by electrical cable. In
this case, the central equipment is available either for installation in

292 © ICS/OCIMF/IAPH 2006