Page 33 - International safety guide for oil tankers and terminals

DEFINITIONS

Torch (also referred to as ‘Flashlight’)
A battery operated hand lamp. An approved torch is one that is approved by a
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competent authority for use in a flammable atmosphere.

Toxicity The degree to which a substance or mixture of substances can harm humans or
The absolute pressure exerted by the gas produced by evaporation from a liquid when์นาวี
animals.
‘Acute toxicity’ involves harmful effects to an organism through a single short term
exposure.
‘Chronic toxicity’ is the ability of a substance or mixture of substances to cause harmful
effects over an extended period, usually upon repeated or continuous exposure,
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sometimes lasting for the entire life of the exposed organism.

True Vapour Pressure (TVP)

gas and liquid are in equilibrium at the prevailing temperature and the gas liquid ratio is
effectively zero. See ‘Reid Vapour Pressure’.

Ullage
The space above the liquid in a tank, conventionally measured as the distance from the
calibration point to the liquid surface.

Upper Flammable Limit (UFL)
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The concentration of a hydrocarbon gas in air above which there is insufficient oxygen
to support and propagate combustion. Sometimes referred to as Upper Explosive Limit
(UEL).

Vapour
A gas below its critical temperature.

Vapour Emission Control System (VECS)
An arrangement of piping and equipment used to control vapour emissions during
tanker operations, including ship and shore vapour collection systems, monitoring and
control devices and vapour processing arrangements.

Vapour lock system
Equipment fitted to a tank to enable the measuring and sampling of cargoes without
release of vapour or inert gas pressure.

Volatile petroleum
Petroleum having a flashpoint below 60ºC as determined by the closed cup method
of test.

Water fog
A suspension in the atmosphere of very fine droplets of water usually delivered at a
high pressure through a fog nozzle for use in fire-fighting.

Water spray
A spray of water divided into coarse drops by delivery through a special nozzle for use
in fire-fighting.

© ICS/OCIMF/IAPH 2006 xxxiii