Page 114 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

Class B liquids are generally divided into the two broad categories of
non-volatile and volatile materials. This division is generally sufficient to ensure
---ใช้เพื่อการศึกษาเท่านั้น---
that proper precautions and measures can be specified for handling Class B
liquids. In summary, non-volatile materials have a flashpoint of 60°C (140°F) or
above, as determined by the closed cup method of testing. Volatile materials
break the force of discharge and to build up an unbroken smothering blanket.ย์นาวี
have a flashpoint below 60°C (140°F), as determined by the same method.
Flammable gases are volatile materials that typically have flashpoints at
temperatures at or below the ambient temperature range. Flammable gases
have relatively high vapour pressures, when in the liquid state, compared to
flammable (volatile) liquids.

Low expansion foam, defined and discussed in Section 5.3.2.1, is an effective
agent for extinguishing most hydrocarbon liquid fires. It should be applied so as
งานห้องสมุด ศูนย์ฝกพาณิช
to flow evenly and progressively over the burning surface, avoiding undue
agitation and submergence. This can best be achieved by directing the foam
discharge against any vertical surface adjacent to the fire, both in order to

If there is no vertical surface, the discharge should be advanced in oscillating
sweeps, in the direction of the wind when possible, taking care to avoid foam
plunging into the liquid. Foam spray streams, while limited in range, are also
effective.

Volatile liquid fires of limited size can be rapidly extinguished with dry chemical
agents, but are subject to re-ignition when hot surfaces are in contact with
ึ
flammable vapours.
Non-volatile liquid fires that have not been burning for an extended period can
be extinguished by water fog or water spray if the whole burning surface is
accessible. The surface of the burning oil transfers its heat rapidly to water
droplets, which present a very large cooling surface area. The flame can be
extinguished with advancing and oscillating sweeps of fog or spray across the
complete width of the fire. Any oil fire that has been burning for some time is
more difficult to extinguish with water, since the oil will have been heated to a
progressively greater depth and cannot readily be cooled to a point where it
ceases to give off gas.

Water should only be applied to oil fires as a spray or fog. The use of a water
jet may spread the burning oil by splashing or overflow.

An aspect that must be borne in mind with liquid petroleum is the risk of
re-ignition, so a continuing watch and preparedness should be maintained after
the fire has been extinguished.

5.2.3 Class C – Electrical Equipment Fires

Class C fires involve energised electrical equipment. These fires may be
caused by a short circuit, overheating of circuits or equipment, lightning or fire
spread from other areas. The immediate action should be to de-energise the
electrical equipment. Once de-energised, a non-conductive extinguishing agent
such as carbon dioxide should be used. Dry chemical is an effective
non-conductive extinguishing agent, but is difficult to clean up after use. If the
equipment cannot be de-energised, it is vital that a non-conductive agent
be used.

80 © ICS/OCIMF/IAPH 2006