1.2.1 These Specifications relate to 15 ppm Bilge
Separators. 15 ppm Bilge Separators should be capable of producing an effluent for
discharge to the sea containing not more than 15 ppm of oil irrespective of the
oil content of the feed supplied to it.
1.2.2 The influent, whether emulsified or non-emulsified, which the
system has in practice to deal with, depends on:
.1 the position of
the oil/water interface, with respect to the suction point, in the space being
pumped;
.2 the type of pump used;
.3 the type and degree of closure of any
control valve in the circuit; and
.4
the general size and configuration of the system. Therefore the test rig must be
so constructed as to include not only the 15 ppm Bilge Separator, but also the
pumps, valves, pipes and fittings as shown in figure 2. It is to be so designed
for testing 15 ppm Bilge Separators with and without an integral supply pump.
- For the testing of 15 ppm Bilge Separators having no integral pump, the
centrifugal pump .A. (figure 2) is used to feed the 15 ppm Bilge Separator with
valves 4 and 6 open, and valve 5 closed. The rate of flow from the centrifugal
pump "A" is matched to the design throughput of the 15 ppm Bilge Separator by the
adjustment of the centrifugal pump.s discharge valve.
- Where the 15 ppm Bilge Separator is fitted with an integral
pump, the centrifugal pump "A" is not required.
- 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. Re-circulation is not required for Test Fluids A and B.
- To ensure a good mix of the Test Fluid and
the water, a conditioning pipe as specified in paragraph 1.2.5 of part 1 of this
annex shall be fitted immediately before the 15 ppm Bilge Separator.
- Other valves, flow meters and sample points
should be fitted to the test rig as shown in figure 2.
- The pipe work should be designed for a maximum liquid velocity
of 3 metres/second.
1.2.3 The tests should be carried out
with a supply rate equal to the full throughput for which the 15 ppm Bilge
Separator is designed.
1.2.4 Tests
should be performed using three grades of test fluids
.1 Test Fluid
.A. which is a marine residual fuel oil in accordance with ISO 8217, type RMG 35
(density at 15oC not less than 980 kg/m3)
.2 Test Fluid "B" which is a marine distillate fuel oil in accordance
with ISO 8217, type DMA (density at 15oC not less than 830 kg/m3).
.3 Test Fluid "C" which is a mixture of
an oil-in-fresh water emulsion, in the ratio whereby 1 kg of the mixture consists
of
- 947.8 g of fresh water;
- 25.0 g of Test Fluid .A"
-
25.0 g of Test Fluid .B.;
- 0.5 g surfactant
(sodium salt of dodecylbenzene sulfonic acid) in the dry form;
- 1.7 g .iron oxides. (The term .iron oxide. is used to
describe black ferrosoferric oxide (Fe3 O4) with a particle size distribution of
which 90% is less than 10 microns, the remainder having a maximum particle size of
100 microns);
Note: Procedure for preparing Test Fluid C: (see
example calculation)
1_________
- Preparation
(1) measure out
1.2 times the quantity of surfactant required for the .Test with Test Fluid C. as
described in 1.2.11; and
(2) mix it
with fresh water and stir well in a small container (e.g., a beaker or bucket) to
make a mixture (.Mixture D.) until the surfactant has been thoroughly dissolved.
- To make Test Fluid C in the test fluid tank (figure
3),
(3) Fill test fluid tank with fresh water with a
quantity 1.2 times the volume of the total quantity of water in the test fluid .C.
needed for the test described in 1.2.11.
(4) Operate centrifugal pump B running at a speed of not less than
3,000 rpm (nominal) with a flow rate at which the volume of the test fluid has
been changed out at least once per minute.
(5) Add .Mixture D. first, followed by oil and suspended solids (iron
oxides) respectively, both 1.2 times of the required amounts, to the fresh water
in the tank,
(6) To establish a stable
emulsion keep running the centrifugal pump B for one hour and confirm no oil
floats on the surface of the test fluid.
(7) After the one hour stated in paragraph (6) above keep running the
centrifugal pump B at reduced speed to approximately 10% of original flow rate,
until the end of the test.
Note:
(1) The
tank should be of a cylindrical shape. The level of the water should be: 2D
> H
> 0.5D, when preparing Test Fluid .C..
(2) Outlet going to centrifugal pump
B should be placed at as low a position to the tank as possible.
(3) Inlet to the tank should be fitted at the center
of tank bottom so that the mixture flows upward to obtain uniform and stable
emulsion. If the 15 ppm Bilge Separator is fitted with heating facilities to allow
the separated oil retained in it to be discharged when the automatic discharge
valve is activated, the Certificate of Type Approval should be endorsed under the
heading .Limiting Conditions Imposed. with the following statement:
- "The 15 ppm separator is fitted with
heating facility." 1.2.5 If the 15
ppm Bilge Separator includes an integrated feed pump, this 15 ppm Bilge
Separator should be tested with that pump supplying the required quantity of
Test Fluid and water to the 15 ppm Bilge Separator at its rated capacity. If the 15 ppm Bilge Separator is to be fed
by the ship.s bilge 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 that 1,000 rpm (see dotted line in
figure 2). This pump should have a delivery capacity of not less than 1.1
times the rated capacity of the 15 ppm Bilge Separator at the delivery
pressure required for the test. The variation in Test Fluid/water ratio will
be obtained by adjusting valves on the Test Fluid and water suction pipes
adjacent to the pump suction, and the flow rate of Test Fluid and water or the
Test Fluid content of the supply to the 15 ppm Bilge Separator should be
monitored. 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 the 15 ppm Bilge Separator should
be such that the influent to the 15 ppm Bilge Separator 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 the 15 ppm Bilge Separator should have a
length not less than 20 times its diameter. A mixture inlet sampling point and
a thermometer pocket should be provided near the 15 ppm Bilge Separator inlet
and an outlet sampling point and observation window should be provided on the
discharge pipe. 1.2.6 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 4 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. 1.2.7 In the case of the 15 ppm
Bilge Separator 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 40°C, and heating and cooling coils should be provided
where necessary. The water shall have a density of not more than 1,015 at
20°C. 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 10°C to 40°C or should be taken at a temperature in
this range where the separation efficiency is known to be worst. 1.2.8 In those cases where, for the
15 ppm Bilge Separator, 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. 1.2.9 The tests with Test Fluid .A. should be carried out as
follows: .1 To ensure that the 15 ppm Bilge Separator commences
the test with the oil section full of Test Fluid and with the supply line
impregnated with Test Fluid, the 15 ppm Bilge Separator should, after filling
with water (density at 20°C not more than 1,015) and while in the
operating condition, be fed with pure Test Fluid for not less than 5 min. .2 The 15 ppm Bilge Separator should
be fed with a mixture composed of between 5,000 and 10,000ppm of Test Fluid in
water until steady conditions have been established. Steady conditions are
assumed to be the conditions established after pumping through the 15 ppm
Bilge Separator a quantity of Test Fluid/water mixture not less than twice the
volume of the 15 ppm Bilge Separator. The test should then proceed for 30 min.
Samples should be taken at the effluent outlet at 10 min and 20 min from the
start of this period. At the end of this test, an air cock should be opened on
the suction side of the pump and, if necessary, the oil 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).
.3 A test identical to that
described in 1.2.9.2, including the opening of the air cock, should be carried
out with a mixture composed of approximately 25%* Test Fluid and 75%* water.
.4 The 15 ppm Bilge Separator
should be fed with 100%* of Test Fluid for at least 5 min during which time
the observation window should be checked for any oil discharge. Sufficient
Test Fluid should be fed into the 15 ppm Bilge Separator to operate the
automatic oil discharge valve. After the operation of the oil discharge valve,
the test should be continued for 5 min using a 100%* Test Fluid supply in
order to check the sufficiency of the oil discharge system. .5 The 15 ppm Bilge Separator should be fed with
water (density at 20°C not more than 1,015) for 15 min. Samples of the
separated water effluent are taken at the beginning of the test and after the
first 10 min. .6 A test lasting a
minimum of 2 h should be carried out to check that the 15 ppm Bilge Separator
will operate continuously and automatically. This trial should use a cycle
varying progressively from water to oily mixture with approximately 25%* Test Fluid content and back to water every
15 minutes, and should test adequately any automatic device which is fitted.
The whole test sequence should be performed as a continuous programme. At the
end of the test, while the 15 ppm Bilge Separator is being fed with 25%* Test
Fluid, a water effluent sample should be taken for analysis. 1.2.10 The
tests with Test Fluid .B. should be carried out as follows: .1 The
15 ppm Bilge Separator should be fed with a mixture composed of between 5,000
and 10,000ppm of Test Fluid in water until steady conditions have been
established. Steady conditions are assumed to be the conditions established
after pumping through the 15 ppm Bilge Separator a quantity of Test
Fluid/water mixture not less than twice the volume of the 15 ppm Bilge
Separator. The test should then proceed for 30 min. Samples should be taken at
the effluent outlet at 10 min and 20 min from the start of this period. At the
end of this test, an air cock should be opened on the suction side of the pump
and, if necessary, the oil 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 A test identical to that described in 1.2.10.1,
including the opening of the air cock, should be carried out with a mixture
composed of approximately 25%* Test Fluid and 75%* water. ________ * Percentage of volume.1.2.11 The tests with Test Fluid
.C. should be carried out as follows: .1 The 15 ppm Bilge
Separator 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 the 15 ppm Bilge Separator a
quantity of Test Fluid .C./water mixture not less than twice the volume of the
15 ppm Bilge Separator. .2 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). 1.2.12 Sampling should be carried
out as shown in figure 4 so that the sample taken will suitably represent the
fluid issuing from the effluent outlet of the 15 ppm Bilge Separator. 1.2.13 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. 1.2.14 The oil content of the samples
should be determined in accordance with part 4 of the annex. 1.2.15 When accurate and reliable oil content
meters are fitted at inlet and outlet of the 15 ppm Bilge Separator, 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. 1.2.16 In the
presentation of the results, the following data testing methods and readings
should be reported: .1 Properties of test fluids A and B: - density at 15ºC; - kinematic viscosity (centistokes @ 100ºC /40ºC); - flashpoint; - ash; and - water
content; .2 Properties of test
fluid C: - type of surfactant; - particle size percentage of the non
soluble suspended solids; and - surfactant
and iron oxide quality verification; .3 Properties of the water in the water tank: - density of water at 20ºC; and - details of any solid matter present; .4 Temperature at the inlet to the 15 ppm Bilge
Separator; .5 A diagram of the test
rig; .6 A diagram of the sampling
arrangement; and .7 The method used
in analysis of all samples taken and the results thereof, together with oil
content meter readings, where appropriate.