Page 380 - International safety guide for oil tankers and terminals
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INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS
completely closed during conditions of high temperatures and humidity, this
discomfort should be accepted in the interests of safety.
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24.2 Central Air Conditioning and Ventilation Systems
There is a benefit from having a gas detection and/or alarm system fitted to airิชย์นาวี
On ships with central air conditioning units, it is essential that the accommodation is
kept under positive pressure to prevent the entry of hydrocarbon vapours. Intakes for
air conditioning units are usually positioned in a safe area and vapours will not be
drawn into the accommodation under normal conditions. A positive pressure will be
maintained only if the air conditioning system is operating with its air intakes open
and if all access doors are kept closed, except for momentary entry or exit. The
system should not be operated with the intakes fully closed, that is in 100%
recirculation mode, because the operation of extraction fans in galley and sanitary
งานห้องสมุด ศูนย์ฝกพาณ
spaces will reduce the atmospheric pressure in the accommodation to less than that
of the ambient pressure outside.
conditioning intakes. In the event that hydrocarbon vapours are present at the inlets,
the ventilation system should be shut down and transfer of cargo suspended until
such time as the surrounding atmosphere is free of hydrocarbon vapours.
The same principles of positive pressure and gas detection apply to ships that have
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alternative air conditioning systems or where additional units have been fitted. The
overriding consideration in all cases is that hydrocarbon vapours must not be
permitted to enter the accommodation.
Externally located air conditioning units, such as window or split air conditioning
types, should not be operated during any of the operations listed in Section 24.1
unless they are either located in safe areas or are certified as safe for use in the
presence of flammable vapours.
On ships that depend on natural ventilation, ventilators should be kept trimmed to
prevent the entry of petroleum gas. If ventilators are located so that petroleum gas
can enter regardless of the direction in which they are trimmed, they should be
covered, plugged or closed.
24.3 Openings in Cargo Tanks
24.3.1 Cargo Tank Lids
During the handling of volatile petroleum and the loading of non-volatile
petroleum into tanks containing hydrocarbon vapour, and while ballasting
after the discharge of volatile cargo, all cargo tank lids should be closed
and secured.
Cargo tank lids or coamings should be clearly marked with the number
and location (port, centre or starboard) of the tank they serve.
Tank openings of cargo tanks that are not gas free should be kept closed,
unless gas freeing operations are being conducted alongside by prior
agreement.
346 © ICS/OCIMF/IAPH 2006