To ensure that the instrument and automation systems provide for the safe carriage and
handling of cargoes.
11.1 General
11.1.1 Each cargo tank should be provided with a means for indicating level.
11.1.2 If loading and unloading of the vessel is performed by means of remotely
controlled valves and pumps, all controls and indicators associated with a given cargo
tank should be concentrated in at least one cargo control station.
11.1.3 Instruments should be tested to ensure reliability under working conditions and
recalibrated at regular intervals. Test procedures for instruments and the intervals
between recalibration should be in accordance with manufacturers' recommendations.
11.2 Level indicators for cargo tanks
11.2.1 Each cargo tank should be fitted with a liquid level gauging device or devices,
arranged to ensure a level reading is always obtainable whenever the cargo tank is
operational. The device(s) should be designed to operate throughout the design pressure
range of the cargo tank and at temperatures within the cargo operating temperature
range.
11.2.2 Where the installation of liquid level gauging devices are impractical due to the
properties of the cargo, such as liquid muds, a visual means of indicating the cargo
tank level should be provided for cargo loading operations, subject to approval by the
Administration.
11.2.3 Where only one liquid level gauge is fitted, it should be arranged so that it can
be maintained in an operational condition without the need to empty or gas free the
tank.
11.2.4 Cargo tank liquid level gauges may be of the following types, subject to special
requirements for particular cargoes shown in column j in the table of chapter
17 of the IBC Code:
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.1 Open device, which makes use of an opening in the tanks and may expose the
gauge to the cargo or its vapour. An example of this is the ullage opening.
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.2 Restricted device, which penetrates the tank and which, when in use, permits a
small quantity of cargo vapour or liquid to be exposed to the atmosphere. When not
in use, the device is completely closed. The design should ensure that no
dangerous escape of tank contents (liquid or spray) can take place in opening the
device.
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.3 Closed device, which penetrates the tank but which is part of a closed system
and keeps tank contents from being released. Examples are the float-type systems,
electronic probe, magnetic probe and protected sight-glass. Alternatively, an
indirect device which does not penetrate the tank shell and which is independent
of the tank may be used. Examples are weighing of cargo and pipe flowmeter.
11.3 Overflow control
The requirements of 15.19 of the IBC Code are applicable where specific reference is made in
column o in the table of chapter 17 thereof, and are in addition to the provisions for
gauging devices as stated in 11.2.
11.4 Vapour detection
11.4.1 Vessels carrying toxic or flammable products or both should be equipped with at
least two instruments designed and calibrated for testing for the specific vapours in
question. If such instruments are not capable of testing for both toxic concentrations
and flammable concentrations, then two separate sets of instruments should be provided.
11.4.2 Vapour-detection instruments may be portable or fixed. If a fixed system is
installed, at least one portable instrument should be provided.
11.4.3 When toxic-vapour-detection equipment is not available for some products which
require such detection, as indicated in column k in the table of chapter
17 of the IBC Code, the Administration may exempt the vessel from the
requirement, provided an appropriate entry is made on the Certificate of Fitness. When
granting such an exemption, the Administration should recognize the necessity for
additional breathing-air supply and an entry should be made on the Certificate of
Fitness drawing attention to the requirements of 14.2.4 and
16.4.2.2
of the IBC Code.
11.4.4 Vapour-detection requirements for individual products are shown in column k in
the table of chapter 17 of the IBC Code.