1.1.1 The specifications in respect of oil filtering
equipment are considered to be applicable for use in conjunction with
oily bilge-water and ballast water from fuel oil tanks, as these are
of a low or medium capacity, and are conditioned by the need to avoid
discharging oily mixtures with an oil content more than 15 ppm of
the mixture.
1.1.2 It is recognized that the development and
testing of high capacity separating equipment designed for dealing
with effluent from cargo tanks on tankers pose special problems and
such equipment does not require to be tested under these specifications.
Such development and tests should not be hindered and Administrations
should be prepared to accept deviations from these specifications
when they are considered necessary in this context.
1.1.3 It should be understood that a gravitational
filtering equipment cannot be expected to be effective over the complete
range of oils which might be carried on board ship, nor can it deal
satisfactorily with oil of very high relative density or with a mixture
presented to it as an emulsion. Cleansing agents used for cleaning
purposes in machinery spaces may cause these emulsions in bilge water.
To avoid this, only those cleansing agents which do not affect the
performance of the equipment should be used, and care should be taken
that the bilge water is fed to the filtering equipment after the emulsion
has broken. Considering that not all designs of equipment are affected
in the same way by cleansing agents, the manufacturers of filtering
and monitoring equipment should supply recommendations concerning
the use of cleansing agents, and these recommendations should be followed
in shipboard practice.
1.1.4 Where a range of filtering equipment of
the same design, but of different capacities, requires certification
in accordance with these specifications, and where the largest capacity
in the range does not exceed 50 m3 per hour, the Administration
may accept tests in two capacities within the range, in lieu of tests
on every size, providing that the two tests actually performed are
from the lowest quarter and highest quarter of the range.
1.1.5 Regulations referred to in these Guidelines
and Specifications are those contained in Annex
I of MARPOL 73/78.