1.1 Flow table test procedure
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Statutory Documents - IMO Publications and Documents - International Codes - IMSBC Code – International Maritime Solid Bulk Cargoes Code – Resolution MSC.268(85) - Appendix 2 – Laboratory Test Procedures, Associated Apparatus and Standards - 1 Test procedures for materials which may liquefy and associated apparatus - 1.1 Flow table test procedure

1.1 Flow table test procedure

  1.1.1 Scope

 The flow table is generally suitable for mineral concentrates or other fine material with a maximum grain size of 1 mm. It may also be applicable to materials with a maximum grain size up to 7 mm. It will not be suitable for materials coarser than this and may also not give satisfactory results for some materials with high clay content. If the flow table test is not suitable for the material in question, the procedures to be adopted should be those approved by the authority of the port State.

 The test described below provides for determination of:

  • .1 the moisture content of a sample of cargo, hereinafter referred to as the test material;

  • .2 the flow moisture point (FMP) of the test material under impact or cyclic forces of the flow table apparatus; and

  • .3 the transportable moisture limit of the test material.

  1.1.2 Apparatus (see figure 1.1.2)

  • .1 Standard flow table and frame (ASTM Designation (C230-68) – see 3).

  • .2 Flow table mounting (ASTM Designation (C230-68) – see 3).

  • .3 Mould (ASTM Designation (C230-68) – see 3).

  • .4 Tamper (see figure the required tamping pressure may be achieved by using calibrated, spring-loaded tampers (examples are included in figure or some other suitable design of tamper that allows a controlled pressure to be applied via a 30 mm diameter tamper head.

  • .5 Scales and weights (ASTM Designation (C109-73) – see 3) and suitable sample containers.

  • .6 Glass graduated measuring cylinder and burette having capacities of 100-200 ml and 10 ml, respectively.

  • .7 A hemispherical mixing bowl approximately 30 cm diameter, rubber gloves and drying dishes or pans. Alternatively, an automatic mixer of similar capacity can be used for the mixing operations. In this case, care should be exercised to ensure that the use of such a mechanical mixer does not reduce the particle size or consistency of the test material.

  • .8 A drying oven with controlled temperature up to approximately 110°C. This oven should be without air circulation.

  1.1.3 Temperature and humidity

 It is preferable to work in a room where the samples will be protected from excessive temperatures, air currents and humidity variations. All phases of the material preparation and testing procedure should be accomplished in a reasonable space of time to minimize moisture losses and, in any event, within the day of commencement. Where possible, sample containers should be covered with plastic film or other suitable cover.

  1.1.4 Procedure

 The quantity of material required for a flow moisture test will vary according to the specific gravity of the material to be tested. It will range from approximately 2 kg for coal to 3 kg for mineral concentrates. It should be collected as a representative sample of the cargo being shipped. Experience has shown that more accurate test results will be obtained by ensuring that the moisture content of the test sample is increased rather than decreased towards the FMP.

 Consequently, it is recommended that a preliminary flow moisture test should be conducted, generally in accordance with the following, to indicate the condition of the test sample, i.e. the quantity of water and the rate at which it is to be added or whether the sample should be air-dried to reduce its moisture content before commencing the main flow moisture test. Preparation of the test sample

 The representative sample of test material is placed in the mixing bowl and thoroughly mixed. Three subsamples (A), (B) and (C) are removed from the mixing bowl as follows: about one fifth of the sample (A) should be immediately weighed and placed in the drying oven to determine the moisture content of the sample “as received”. Two further subsamples, each of about two fifths of the gross weight, should then be taken, one (B) for the preliminary FMP test and the other (C) for the main FMP determination:

  • .1 Filling the mould. The mould is placed on the centre of the flow table and filled in three stages with the material from the mixing bowl. The first charge, after tamping, should aim to fill the mould to approximately one third of its depth. The quantity of sample required to achieve this will vary from one material to another, but can readily be established after some experience has been gained of the packing characteristics of the material being tested.

  • The second charge, after tamping, should fill the mould to about two thirds of its depth and the third and final charge, after tamping, should reach to just below the top of the mould (see figure 1.1.4-2).

  • .2 Tamping procedure. The aim of tamping is to attain a degree of compaction similar to that prevailing at the bottom of a shipboard cargo of the material being tested. The correct pressure to be applied is calculated from:

  • Tamping pressure (Pa) = Bulk density of cargo (kg/m3)

        • x Maximum depth of cargo (m)

          x Gravity acceleration (m/s2)

  • Bulk density can be measured by a single test, using the Proctor C apparatus described in ASTM Standard D-698 or JIS-A-1210, on a sample of the cargo at the proposed moisture content of loading.

  • When calculating the tamping pressure, if no information concerning cargo depth is available the maximum likely depth should be used.

  • Alternatively, the pressure may be estimated from table

  • The number of tamping actions (applying the correct, steady pressure each time) should be about 35 for the bottom layer, 25 for the middle and 20 for the top layer, tamping successively over the area completely to the edges of the sample to achieve a uniformly flat surface for each layer.

  • .3 Removal of the mould. The mould is tapped on its side until it becomes loose, leaving the sample in the shape of a truncated cone on the table.

Typical cargo Bulk density (kg/m3) Maximum cargo depth
2 m 5 m 10 m 20 m
Tamper pressure (kPa)
Coal 1,000 20 (1.4) 50 (3.5) 100 (7.1) 200 (14.1)
  2,000 40 (2.8) 100 (7.1) 200 (14.1) 400 (28.3)
Metal ore 3,000 60 (4.2) 150 (10.6) 300 (21.2) 600 (42.4)
Iron ore concentrate 4,000 80 (5.7) 200 (14.1) 400 (28.3) 800 (56.5)
Lead ore concentrate 5,000 100 (7.1) 250 (17.7) 500 (35.3) 1,000 (70.7)
(values in parenthesis are equivalent kgf when applied via a 30 mm diameter tamper head) The preliminary flow moisture test

  • .1 Immediately after removing the mould, the flow table is raised and dropped up to 50 times through a height of 12.5 mm at a rate of 25 times per min. If the material is below the FMP, it usually crumbles and bumps off in fragments with successive drops of the table (see figure 1.1.4-3).

  • .2 At this stage, the flow table is stopped and the material returned to the mixing bowl, where 5-10 ml of water, or possibly more, is sprinkled over the surface and thoroughly mixed into the material, either with rubber-gloved fingers or an automatic mixer.

  • The mould is again filled and the flow table is operated as described in for up to 50 drops. If a flow state is not developed, the process is repeated with further additions of water until a flow state has been reached.

  • .3 Identification of a flow state. The impacting action of the flow table causes the grains to rearrange themselves to produce compaction of the mass. As a result, the fixed volume of moisture contained in the material at any given level increases as a percentage of the total volume. A flow state is considered to have been reached when the moisture content and compaction of the sample produce a level of saturation such that plastic deformation occursfootnote. At this stage, the moulded sides of the sample may deform, giving a convex or concave profile (see figure 1.1.4-4).

  • With repeated action of the flow table, the sample continues to slump and to flow outwards. In certain materials, cracks may also develop on the top surface. Cracking, with the appearance of free moisture, is not, however, an indication of development of a flow state. In most cases, measurement of the deformation is helpful in deciding whether or not plastic flow has occurred. A template which, for example, will indicate an increase in diameter of up to 3 mm in any part of the cone is a useful guide for this purpose. Some additional observations may be useful. For example: when the (increasing) moisture content is approaching the FMP, the sample cone begins to show a tendency to stick to the mould. Further, when the sample is pushed off the table, the sample may leave tracks (stripes) of moisture on the table. If such stripes are seen, the moisture content may be above the FMP: the absence of tracks (stripes) is not necessarily an indication of being below the FMP.

  • Measuring the diameter of the cone, at the base or at half height, will always be useful. By addition of water in increments of 0.4% to 0.5% and applying 25 drops of the flow table, the first diameter increase will generally be between 1 and 5 mm and after a further increment of water the base diameter will have expanded by between 5 and 10 mm.

  • .4 As an alternative to the procedure described above, for many concentrates a fast way of finding the approximate FMP is as follows:

  • When the moisture content is definitely beyond the FMP, measure the diameter after 25 drops, repeat the test after adding a further increment of water, measure the diameter and draw a diagram as illustrated in figure 1.1.4-1, showing increase in diameter plotted against moisture content. A straight line drawn through the two points will cross the moisture content axis close to the FMP.

 Having completed the preliminary FMP test, the sample for the main test is adjusted to the required level of moisture content (about 1% to 2%) below the flow point. Main flow moisture test

 When a flow state has been reached in the preliminary test, the moisture content of subsample (C) is adjusted to about 1% to 2% less than the last value which did not cause flow in the preliminary test (this is suggested simply to avoid starting the main test too close to the FMP and then having to waste time air-drying it and starting again). The final test is then carried out on this adjusted sample in the same manner as for the preliminary test, but in this case with the addition of water in increments of no more than 0.5% of the mass of the test material (the lower the “preliminary” FMP, the smaller the increments should be). After each stage, the whole moulded sample should be placed in a container, weighed immediately and retained for moisture determination if required. This will be necessary if the sample flowed or if the next, slightly wetter, sample flows. If not required, it may be returned to the mixing bowl.

 When a flow state has been reached, the moisture content should be determined on two samples, one with moisture content just above the FMP and the other with moisture content just below the FMP. The difference between the two values should then be 0.5% or less, and the FMP is taken as the mean of these two values. Determination of moisture content


It should be noted that, for many materials, there are recognized international and national methods for determining moisture content. These methods, or ones that have been established to give equivalent results, should be followed.

 Concentrates and similar materials

It is clearly important that the samples should be dried to a constant mass. In practice, this is ascertained after a suitable drying period at 105°C by weighing the sample successively with an interval of several hours elapsing. If the mass remains constant, drying has been completed, whereas if the mass is still decreasing, drying should be continued.

 The length of the drying period depends upon many variables, such as the disposition of the material in the oven, the type of container used, the particle size, the rate of heat transfer, etc. It may be that a period of five hours is ample for one concentrate sample, whereas it is not sufficient for another. Sulphide concentrates tend to oxidize, and therefore the use of drying ovens with air circulation systems is not recommended for these materials, nor should the test sample be left in the drying oven for more than four hours.


The recommended methods for determination of the moisture content are those described in ISO 589-1974, “Hard Coal – Determination of Total Moisture”. This method, or ones that have been established to give equivalent results, should be followed.

  Calculation of moisture content, FMP and transportable moisture limit:

Taking m1 as the exact mass of the subsample “as received” (see,

Taking m2 as the exact mass of the “as received” subsample, after drying,

Taking m3 as the exact mass of the sample just above the flow state (see,

Taking m4 as the exact mass of the sample just above the flow state, after drying,

Taking m5 as the exact mass of the sample just below the flow state (see,

Taking m6 as the exact mass of the sample just below the flow state, after drying,


  • .1 The moisture content of the concentrate “as received” is:

  • .2 The FMP of the material is:

  • .3 The transportable moisture limit of the material is 90% of the FMP.

 Peat moss

For all peat moss, determine the bulk density, using either the ASTM or CEN (20 L) method.

Peat should be above or below 90 kg/m3 on a dry weight, basis in order to obtain the correct TML.

As indicated in 1.1.1, the following should be determined:

  • .1 the moisture content of a sample of cargo (MC);

  • .2 the flow moisture point (FMP);

  • .3 the transportable moisture limit (TML). The TML will be determined as follows:

    • .3.1 for peat with a bulk density of greater than 90 kg/ m3 on a dry weight, the TML is 85% of the FMP; and

    • .3.2 for peat with a bulk density of 90 kg/ m3 or less on a dry weight, the TML is 90% of the FMP.

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