2 - Test specifications
2.1 These specifications relate to add-on equipment for oil filtering
equipment. A set of oil filtering equipment and 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.
2.2 The test rig must be so constructed as to include not only oil
filtering equipment and add-on equipment, but also the pumps, valves, pipes and fittings as
shown in figure 1:
- for the testing of oil filtering equipment having no integral pump, the centrifugal
pump "A" (figure 1) is used to feed oil filtering equipment with valves 2 and 4 open, and
valve 3 closed. The rate of flow from the centrifugal pump "A" is matched to the design
throughput of oil filtering equipment by adjustment of the centrifugal pump's discharge
valve;
- 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 throughout the
testing;
- to ensure a good mix of the test fluid and the water, a conditioning pipe as specified
in paragraph 2.4 should be fitted immediately before oil filtering equipment;
- other valves, flow meters and sample points should be fitted to the test rig as shown
in figure 1; and
- the pipe work should be designed for a maximum liquid velocity of 3 metres/second.
Figure 1 – Test rig
2.3 Tests should be performed using test fluid "C" as
defined in resolution MEPC.107(49).
2.4 If oil filtering equipment includes an integrated feed pump, oil
filtering equipment and add-on equipment should be tested with that pump supplying the
required quantity of test fluid and water to oil filtering equipment at its rated capacity.
If oil filtering equipment is to be fed by the ship's pumps, then the unit will be tested
by supplying the required quantity of test fluid and water mixture to the inlet of a
centrifugal pump operating at not less than 1,000 rpm (see dotted line in figure 1). This
pump should have a delivery capacity of not less than 1.1 times the rated capacity of oil
filtering equipment at the delivery pressure required for the test. If a centrifugal pump
is used, 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 oil filtering equipment should be such that the influent to oil
filtering 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 oil filtering equipment hould have a
length not less than 20 times its diameter. A mixture inlet sampling point and a
thermometer pocket should be provided near oil filtering equipment inlet and an outlet
sampling point and observation window should be provided on the discharge pipe.
Figure 2 - Diagram of sampling arrangements
A Distance A, not greater than 400 mm
B Distance B,
sufficient to insert sampling bottle
C Dimension C, straight length
should not be less than 60 mm
D Dimension D, pipe thickness should
not be greater than 2 mm
E Detail E, chisel-edged chamfer (30°)
2.5 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 effected for at least one
minute before any sample is taken.
The sampling points should be in pipes
running vertically.
2.6 In the case of oil filtering equipment and add-on
equipment depending essentially on gravity, the feed to the system 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 shall 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.
2.7 In those cases where, for oil filtering equipment and
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.
2.8 The tests with test fluid "C" should be carried out as
follows:
prior to the test with test fluid "C", oil filtering equipment and
add-on equipment should be filled up with water (density of not more than 1.015 at
20ºC);
oil filtering equipment and 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 oil
filtering equipment and add-on equipment a quantity of test fluid "C"/water mixture not
less than twice the volume of oil filtering and add-on equipment; and
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).
2.9 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.
2.10 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.
2.11 The oil content of the samples should be determined in
accordance with part 4 of the annex to resolution MEPC.107(49).
2.12 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.