5.1.1 The monitoring system should be capable
of effectively monitoring and controlling the discharge of any effluent
into the sea through those overboard discharge outlets permitted by regulation 18 which, in the opinion
of the Administration, are necessary to fulfil the operational requirements
of the oil tanker.
5.1.2 The discharge of dirty ballast water or
other oil-contaminated water from the cargo tank areas into the sea
through outlets which are not controlled by the monitoring system
is an infringement of the Convention.
5.1.3 The monitoring system should function effectively
under all environmental conditions which oil tankers are normally
assumed to encounter, and should be designed and constructed to satisfy
the specifications for environmental testing specified in part 2 of
the Annex to these Guidelines and Specifications. Moreover,
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.1 the system should, except as permitted for
a category B system, be so designed that no discharge of dirty ballast
or other oil-contaminated water from the cargo tank areas can take
place unless the monitoring system is in the normal operating mode
and the relevant sampling point has been selected;
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.2 preferably the system should sample the effluent
discharge from a minimum number of discharge outlets and be so arranged
that discharge overboard can take place via only one outlet at a time;
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.3 where it is intended that more than one line
be used for simultaneous discharging purposes, one oil content meter,
together with a flow meter, should be installed in each discharge
line. These instruments should be connected to a common processor;
and
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.4 in order to avoid alarms due to short-term
high oil concentration signals (spikes) causing indications of high
instantaneous rates of discharge, the short-term high ppm signal may
be suppressed for a maximum of 10 seconds. Alternatively, the instantaneous
rate of discharge may be continuously averaged during the preceding
20 seconds or less as computed from instantaneous ppm values of the
oil content meter readings received at intervals not exceeding 5 seconds.
5.1.4 The monitoring system should comprise:
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.1 an oil content meter to measure the oil content
of the effluent in ppm. The meter should be approved in accordance
with the provisions contained in the Annex to these Guidelines and
Specifications and be certified to take into account the range of
cargoes carried;
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.2 a flow rate indicating system to measure the
rate of effluent being discharged into the sea. For a category B monitoring
system, where the flow rate may be inserted into the computing unit
manually, the arrangement described in paragraph
5.4.7 should be used;
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.3 a vessel speed indicating device to give the
vessel's speed in knots. For a category B monitoring system, where
the vessel's speed may be inserted into the computing unit manually,
the arrangement described in paragraph
5.5.2 should be used;
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.4 a sampling system to convey a representative
sample of the effluent to the oil content meter;
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.5 an overboard discharge control to stop the
overboard discharge. For a category B system the arrangement for stopping
the overboard discharge may be manual;
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.6 a starting interlock to prevent the discharge
overboard of any effluent unless the monitoring system is fully operational.
A category B system requires no starting interlock;
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.7 a control section comprising:
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.7.1 a processor, which accepts signals of oil
content in the effluent, the effluent flow rate and the vessel's speed
and computes these values into litres of oil discharged per nautical
mile and the total quantity of oil discharged;
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.7.2 means to provide alarms and, for a category
A monitoring system, command signals to the overboard discharge control;
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.7.3 a recording device to provide a record of
data in accordance with paragraph 5.8.2;
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.7.4 a data display to exhibit the current operational
data in accordance with paragraph 5.9;
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.7.5 a manual override system to be used in the
event of failure of the monitoring system; and
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.7.6 for a category A monitoring system, means
to provide signals to the starting interlock to prevent the discharge
of any effluent before the monitoring system is fully operational.
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5.1.5 Each main component of the oil content monitoring
system should be fitted with a name-plate, properly identifying the
component by assembly drawing number, type or model number and serial
number, as appropriate.
5.1.6 If installed in a hazardous area, the electrical
components of the monitoring system should meet the appropriate safety
requirementsfootnote laid down for these
areas.