4.1 These specifications relate to add-on
equipment. The add-on equipment should be capable of producing an
effluent for discharge to the sea containing not more than 15 ppm
of oil when 3,000 ppm oil in water emulsions are fed.
4.2 The test rig must be so constructed as to
include not only add-on equipment but also the pumps, valves, pipes
and fittings as shown in figure 3:
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.1 for the testing centrifugal pump "A" (figure
3) is used to feed the add-on equipment. The rate of flow from the
centrifugal pump "A" is matched to the design throughput of the add-on
equipment by the adjustment of the centrifugal pump's discharge valve;
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2 a centrifugal pump "B" should be fitted to re-circulate
the test fluid C in the tank to ensure that the test fluid C is maintained
in a stable condition throughput the testing;
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.3 to ensure a good mix of the test fluid and
the water, a conditioning pipe as specified in paragraph 4.4 should
be fitted immediately before add-on equipment;
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.4 other valves, flow meters and sample points
should be fitted to the test rig as shown in figure 3; and
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.5 the pipe work should be designed for a maximum
liquid velocity of 3 metres/second.
4.4 The add-on equipment is tested by supplying
the required quantity of test fluid and water mixture to the inlet
by a centrifugal pump operating at not less than 1,000 rpm. This pump
should have a delivery capacity of not less than 1.1 times the rated
capacity of add-on equipment at the delivery pressure required for
the test. The excess pump capacity should be controlled by a throttle
valve on the discharge side of the pump. In all cases, to ensure uniform
conditions, the piping arrangements immediately prior to add-on equipment
should be such that the influent to add-on equipment should have a
Reynolds number of not less than 10,000 as calculated in fresh water,
a liquid velocity of not less than 1 metre per second and the length
of the supply pipe from the point of test fluid injection to add-on
equipment should have a length not less than 20 times its diameter.
A mixture inlet sampling point and a thermometer pocket should be
provided near add-on equipment inlet and an outlet sampling point
and observation window should be provided on the discharge pipe.
4.5 In order to approach isokinetic sampling –
i.e. the sample enters the sampling pipe at stream velocity –
the sampling arrangement should be as shown in figure 2 and, if a
cock is fitted, free flow should be affected for at least one minute
before any sample is taken. The sampling points should be in pipes
running vertically.
Figure 3 Test rig
4.6 In the case of add-on equipment depending
essentially on gravity, the feed to the add-on equipment of the test
water and test fluid mixture should be maintained at a temperature
not greater than 40ºC, and heating and cooling coils should be
provided where necessary. The water should have a density of not more
than 1.015 at 20ºC. In other forms of separation where the dependence
of separation efficiency on temperature is not established, tests
should be carried out over a range of influent temperatures representing
the normal shipboard operating range of 10ºC to 40ºC or
should be taken at a temperature in this range where the separation
efficiency is known to be worst.
4.7 In those cases where, for add-on equipment,
it is necessary to heat water up to a given temperature and to supply
heat to maintain that temperature, the tests should be carried out
at the given temperature.
4.8 The tests with test fluid "C" should be carried
out as follows:
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.1 prior to the test with test fluid "C", add-on
equipment should be filled up with water (density of not more than
1.015 at 20ºC);
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2 add-on equipment should be fed with a mixture
composed of 6% test fluid "C" and 94% water to have emulsified oil
content of 3,000 ppm in the test water until steady conditions have
been established. Steady conditions are assumed to be the conditions
established after pumping through add-on equipment a quantity of test
fluid "C"/water mixture not less than twice the volume of add-on equipment;
and
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.3 the test should then proceed for 2.5 h. Samples
should be taken at the effluent outlet at 50 minutes and 100 minutes
after conditioning. At the end of this test, an air cock should be
opened on the suction side of the pump and, if necessary, the test
fluid "C" and water valves should be slowly closed together, and a
sample taken at the effluent discharge as the flow ceases (this point
can be checked from the observation window).
4.9 Sampling should be carried out as shown in
figure 2 so that the sample taken will suitably represent the fluid
issuing from the effluent outlet of add-on equipment.
4.10 Samples should be taken in accordance with
ISO 9377–2:2000. The sample is to be extracted on the same day
of collection, and be sealed and labelled in the presence of a representative
of the national authority and arrangements should be made for analysis
as soon as possible and in any case within seven days, provided the
samples are being kept between 2ºC and 6ºC at laboratories
approved by the Administration.
4.11 The oil content of the samples should be
determined in accordance with part 4 of the annex to resolution MEPC.107(49).
4.12 When accurate and reliable oil content meters
are fitted at inlet and outlet of add-on equipment, one sample at
inlet and outlet taken during each test will be considered sufficient
if they verify, to within ±10%, the meter readings noted at
the same instant.