5.4.1 A flow meter for measuring the rate of discharge
should be installed in a vertical section of a discharge line or in
any other section of a discharge line as appropriate, so as to be
always filled with the liquid being discharged.
5.4.2 A flow meter should employ an operating
principle which is suitable for shipboard use and, where relevant,
can be used in large diameter pipes.
5.4.3 A flow meter should be suitable for the
full range of flow rates that may be encountered during normal operation.
Alternatively, arrangements such as the use of two flow meters of
different ranges or a restriction of the operational flow rate range
may be necessary to meet this requirement.
5.4.4 The flow meter, as installed, should have
an accuracy of ± 15%, or better, of the instantaneous rate
of discharge throughout the operating range for discharging the effluent.
5.4.5 Any component part of the flow meter in
contact with the effluent should be of corrosion-resistant and oil-resistant
material of adequate strength.
5.4.6 The design of the flow metering arrangements
should have regard to the safety requirements of the space in which
such metering arrangements are located.
5.4.7 In oil tankers fitted with a category B
monitoring system the flow rate may be determined from the pump characteristics
and the data be inserted manually into the computing unit.
5.4.8 In oil tankers fitted with a category B
monitoring system where it is intended to discharge dirty ballast
to the sea by gravity, as permitted by regulation 18(6)(d), means such
as calibration curves should be provided to estimate the flow rate
of discharge and the data should be inserted manually into the computing
unit.