1.1 General
1.1.1 This test and performance specification for type
approval relates to oil content meters. In addition, the electronic section of the oil
content meter should be tested in accordance with the specification for environmental
testing contained in part 2 of this Annex.
1.1.2 The meter being tested should satisfy all the relevant requirements
contained in section 5 of these Guidelines and Specifications.
1.2 Test specifications
1.2.01
A meter designed to operate over a wide range of oil content
should-measure the true one content of the sample entering the meter during each
tests within ± 10 ppm or ± 20% , whichever is the greater, and testing should be
performed in accordance with the procedures detailed in paragraphs 1.2.5 to 1.2.18
of this specification
1.2.02
A diagrammatic arrangement of test rig for evaluating the
performance of oil content meters is given in figure 1. The accuracy of the oil
content meter should be determined by comparing its readings with a known flow of
oil injected into a known flow of waters. The grab samples taken should be analysed
in a laboratory by the method described in paragraph 1.3 of this specification. The
results of the laboratory analysis will be used for correlation and to indicate
sampling and test equipment variability. The water flow rate should be adjusted so
that the entire oil-water flow passes through the oil content meter, except the
intermittent grab sample stream. Special care should be given to keep, continuously,
a constant oil content in the water that flows into the meter. The oil and
contaminant metering pumps should be adjusted to deliver a steady flow. If oil
injection becomes intermittent at low concentrations, the oil may be premixed with
water to provide continuous flow, If absolutely necessary. The oil injection point
should be immediately upstream of the oil content meter inlet to minimize time-lags
caused by the sample system. Wherever Arabian light crude oil is specified in
particular rests, a similar crude oil may be substituted, provided that the oil
selected is used throughout the tests.
1.2.03
The sampling arrangement should be such that a representative
homogeneous sample is obtained under all conditions of operation and under all
operational proportions of oil content. The sample should be obtained at the open
discharge outlet from the meter, but when this is impracticable the sampling
arrangements shown in figure 2 should be used. Special care should be taken in
collecting and preserving the sample to ensure validity of the resultant findings.
1.2.04
Should the oil content meter incorporate a filter or owner
device for removing solid contaminants from the mixture to be tested, such a device
should be regarded as part of the oil content meter and be connected during all the
tests. After completion of the contaminant tests referred to in paragraph 1.2.10 the
device used to remove solid contaminants from the mixture should be opened up and
the residues inspected to ascertain that they do tool contain significant amounts of
oil.
1.2.05
The oil content meter should be calibrated and zeroed in
accordance with the manufacturer's Instructions It should then be tested with
Arabian light crude oil at the following concentrations in ppm: 0, 15, 50, 100, 200
and at intervals of 200 up to the maximum of the meter's highest range. A complete
calibration curve should be constructed. Each concentration tests should last for 15
minutes. After each concentration test the meter should be run on oil-free water
fort 15 minutes and the reading noted.
1.2.06
After calibration in the previous test, the oil content meter
should be tested at concentrations of 15 ppm, 100 ppm and 90 per cent of the maximum
full scale with the following oils:
Type of
oil | Categories
represented |
Sahara
blend | Density - low Viscosity - low Pour point - very low Producing country - Algeria General description - mixed
base |
Arabian light crude
| Density - medium Viscosity
- medium Pour point - low Producing
country - Saudi Arabia General description mixed
base |
Nigerian medium crude
| Density - high Viscosity -
medium Pour point - low Producing country
- Nigeria General description - naphthenic |
Bachaquero 17 crude | Density - very high Viscosity - very high Pour point - low Producing country -
Venezuela General description - asphaltic |
Minas crude | Density - medium Viscosity - high Pour point - very high Producing country -
Indonesia General description - paraffinic |
Residual fuel | Bunker C or No.6 fuel oil |
Note: Other rolls covering the range of
properties shown may be substituted If those shown are unobtainable
Following each test, the meter should be run on oil-free water
for 15 minutes and the meter reading recorded. If it is necessary to re-zero,
recalibrate, dismantle or water-flush to clean the meter between tests, this fact
and the time required to recalibrate or clean the meter should be noted and recorded
on the certificate
1.2.07
If the meter is considered suitable for "white" petroleum
products, It should also be tested with the following products in a manner similar
to the tests set out in paragraph 1.2.6
Automotive gasoline,
Kerosene, and
Light diesel or No.2 fuel oil.
If the meter is to be considered suitable for any of the
category C and D oil-like noxious liquid substances referred to in the list
contained in the unified interpretations to regulation 14 of Annex 11 of MARPOL
73/78, it should also be tested against each such substance for which approval is
required, in a manner similar to the tests set oui in paragraph 1.2.6. The high
shear pump shown in figure 1 should be kept in operation at high speed during this
test to assist in dissolving the appropriate fraction of the substance in the water
stream.
1.2.08
The oil content meter should be run on oil-free water and
zeroed. The oil injection pump, set to 100 ppm Arabian light crude oil, should be
turned on The following response times should be recorded and Included on the
certificate:
- time for first detectable reading,
- time to read 63
ppm, and
- time for reading to stabilize at maximum, the value (ppm) of
which should be recorded.
Following this upscale test, the oil
injection pump should be turned off and the following response times should be
recorded and included on the certificate: - time for the maximum reading
to drop detectably;
- time to read 37 ppm; and
- time for reading
to stabilize at minimum, the value (ppm) of which should be recorded.
The response time of the meter, which should be taken as the average of the response
time recorded to read 63 ppm and the response time recorded to read 37 ppm, should
be less than 20 seconds.
1.2.09
Two tests using Arabian light crude oil should be performed to
determine the effect of oil fouling on calibration shift. The first test should be
done with a 10% oil concentration and the second with a 100% oil concentration
For the 10% oil concentration test the meter
should initially be running on oil-free water. The high capacity oil injection pump,
set to glue 10% oil In water should be turned on for one minute and then turned off.
For the 100% oil concentration test the meter
should be running on oil-free water. The watershould be turned off and oil turned on
for one minute. The oil should then be turned off and the oil-free water flow
resumed.
Care must be taken in the design of the
test equipment to ensure that the oil fouling test results are not degraded by
fouling of the sample piping external to the meter.
The following response times should be noted for both lasts and
recorded on the certificate:
- time for first detectable reading;
- time to read 100 ppm;
- time for reading to go off scale on the
highest range;
- time for reading to return back on scale on the highest
range;
- time for reading to return to 100 ppm; and
- time for
reading to return to zero or stabilize at minimum ppm reading.
If It is necessary to dismantle or water-flush
to clean the meter after each oil fouling test for it to return to a zero reading,
this fact and the time required to clean and recalibrate the meter shall be noted
and recorded on the certificate.
After
successful completion of both oil fouling tests, a 100 ppm mixture of Arabian light
crude oil should be introduced and any calibration shift noted and recorded on the
certificate.
1.2.10
The meter should be run on contaminated water as follows:
- the meter should be run on water, and the contaminant described in .2 of
this paragraph should be added to the water contained in the mixing tank in the
concentration stated. Arabian light crude oil will be added to the mixture of
water and contaminants in the following concentrations
- - 15 ppm;
- - 100 ppm; and
- - 300 ppm;
- the
contaminant should be a mixture containing not less than 270 ppm by weight of
attapulgite (see note (a)) and 30 ppm by weight of iron oxides (see note (b)).
Each material should be mixed sequentially in the mixing tank to the following
criteria: .2.1 attapulgite for a period of not less than 15 minutes so that
a homogeneous suspension is formed; iron oxides for an additional period of not
less than 10 minutes. The mixing process should maintain the contaminants in
suspension throughout the test period;
.2.2 sufficient water
should be available in the mixing tanks to ensure an effective test period of
not less than 15 minutes.
Notes(a) Attapulgite is a clay mineral with
the chemical formula (M g ,A l) 5S i 8O 22( OH ) 44H 2O and Is stable In both fresh
and salt water. The test contaminant should halve a particle she distribution with
about 30% of 10 microns or less and a maximum particle sloe of 100 microns
(b) The term "iron oxides" is used to
describe black ferrosoferric oxide ( Fe3 04 ) With a particle size distribution of
which 90% is less than 10 microns, the remainder having a maximum particle sloe of
100 microns.
1.2.11
The meter should be run on water with air entrainment as
follows
- Air should be injected into the test circuit immediately before the
sample pump or, in the absence of such pump, immediately before any conditioning
unit used to prepare the mixture for measurement. Injection should be by needle
having an orifice dimension not exceeding 0.5 mm in diameter arranged in line
with the sample flow. The quantity of air injected should be 1% of the
designated flow rate of the sample pump or conditioning unit at the point of
injection. Air should be delivered to the system by direct injection or pump via
a suitable measuring device designed to permit a constant controllable flow rate
within ± 10% of the required rate of injection for an uninterrupted effective
test period of not less than 15 minutes.
- Arabian light crude oil should
be added to this mixture of water and 3lr In the following concentrations:
- - 15 ppm;
- - 100 ppm; and
- - 300 ppm.
Any shift in the meter reading should be recorded on the
certificate.
1.2.12
The meter should be run on a mixture of water and Arabian
light crude oil of 100ppm The high shear pump, shown in figure 1, should be run at
various speeds to provide a range of oil particle size to the meter and on
completion of this test the pump should be stopped. Any effect of particle size on
the meter reading should be noted and recorded on the certificate. The purpose of
this tests is to demonstrate that the meter's accuracy is not significantly affected
by the oil droplet size or by the degree of oil and water mixing.
1.2.13
The meter should be run on a mixture of water and Arabian
light crude talk of 100ppm The water temperature should initially be set at 10°C and
then at 65°C. If the manufacturer's specification lists an operating maximum water
temperature of less than 65°C,the metier should be run 3l that maximum temperature
and this fact together with and effect of water temperature on the meter reading
should be recorded on the certificate.
1.2.14
The meter should be run on a mixture of water and Arabian
light crude oil of 100 ppm. The water pressure or flow rate of the mixture should be
adjusted from one-half normal, to normal and to twice normal. Any effect of these
changes on the melee reading should be recorded on the certificate. This test may
require modification, depending on the flow characteristics of the meter.
1.2.15
The meter should be run on a mixture of water and Arabian
light crude oil of 100 ppm. The water and oil injection pumps should be shut off and
the meter left on with no other changes made. After 8 hours, the water and the oil
injection pumps should be turned on and set to provide a mixture of 100 ppm. The
meter readings before and after each test and any damage to the meter should be
recorded on the certificate. This test also determines the proper functioning of the
low flow shut-off and alarm.
1.2.16
The meter should be run on a mixture of water and Arabian
light crude oil of 100 ppm. The supply voltage should be increased to 110% of the
nominal value for one hour and then reduced to 90% of the nominal value for one
hour. Any effect on meter performance should be recorded on the certificate.
If the operation of the meter requires any
utilities besides electricity, It should be tested with these utilities at 110% and
90% of the design figures,
1.2.17
The meter should be calibrated and zeroed in accordance with
the procedures in the manufacturer's instructions manual. A mixture of water and
Arabian light crude oil of 100 ppm should be run through the meter for 8 hours and
any calibration drift recorded on the certificate. Following this, the meter should
be run on oil-free water and any zero drift recorded on the certificate.
1.2.18
The meter should be shutdown and de-energized for one week. It
should be turned on and started in accordance with the manufacturer's instructions.
After the suggested warm-up and calibration procedures, the meter should be run for
a period of 8 hours, operating alternately for one hour on a mixture of water and
Arabian light crude roll of 100 ppm and for one hour on oil-free water. After each
step in the operation, any zero or span drift should be recorded on the certificate.
The total time required to perform the manufacturer's suggested warm-up and
calibration procedures should also be recorded on the certificate.
1.2.19
A specification of the instrument concerned and a diagrammatic
presentation of the test arrangements should be provided to the Administration by
the manufacturer when applying for type approval and the following data should be
reported in the international metric system of units
- types and properties of
oils used in the tests;
- details of contaminants used, in the form, for
example, of a supplier's certificate or laboratory test protocol; and
- results of tests and analysis of grab samples.
Figure 1 - Test rigThe size of the mixing tank should be specified
so as to allow a minimum "once through'' effective test period of 15 minutes.
Adequate arrangements should be made for in-tank mixing of recycling to ensure a
homogeneous mixture.
Figure 2 - Alternative sampling arrangement in test
rig