ISO 3733:1999 pdf free download.Petroleum products and bituminous materials-Determination of water Distillation method.
ISO 3733 specifies a method tar determination of water up to 25 % in petroleum products. bitumens, tars and products derived from these materials, excluding emulsions, by the distillation method. The specific products considered during the development of this test method are listed in Table 3.
ISO 3733 may be used to determine water content in excess of 25 %. However, no precision data has been determined at levels greater than 25 %. Volatile water-soluble material, if present, is measured as water.
NOTE 1 A knowfedge of the water content of petroleum products is important in the refining, purchase, sale and transfer of products.
NOTE 2 The amount of water determined by this method can be used to correct the volume involved in the custody transfer of product.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on ISO 3733 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to appties. Members of ISO and IEC maintain registers of currently valid International Standards.
ISO 3170:1988, Petroleum liquids — Manual sampling.
ISO 3171:1988, Petroleum liquids — Automatic pipeline sampling.
ISO 3405:_i). Petroleum products Determination of distillation characteristics at atmospheric pressure.
3 Principle
The test material is heated under reflux with a water-immiscible solvent, which co-distills with the water in the sample. Condensed solvent and water are continuously separated in a trap, the water settling in the graduated
b) a blend of 20 % (V/I’) industrial grade toluene and 80 % (V/I’) industrial grade xylene (mixed xylenes);
c) petroleum distillate, yielding not more than 5% (VII’) distillates at 125 °C and not less than 20 % (V/I’) at 160 °C when tested in accordance with ISO 3405 and with a density not lower than 855 kglm3 at 15 °C.
4.2 Petroleum distillate solvent
A petroleum solvent, free of water, of which 5% (VII’) boils between 90 °C and 100 °C, and 90% (V/I’) distils below
210°C.
4.3 Paraffinic solvents
The following paratfinic solvents, free of water, are suitable:
a) light petroleum with a boiling range of 100 °C to 120 °C;
b) 2.2,4-tnmethylpentane (iso-octane) of 95 % purity or belier.
5 Apparatus
5.1 General
The apparatus compnses a glass or metal still, a heater, a reflux condenser, and a graduated glass trap. The still, trap and condenser shall be connected by any suitable method that produces a leak-proof joint. Preferred connections are ground joints for glass, and 0-rings for metal to glass. Typical assemb4ies of the glassware are shown in Figures 1 to 3 and the dimensions are given in Table 1. Any given testing apparatus will be deemed suitable, if accurate resufts are obtained using the methods described in 6.2 and 6.3. However, a straight water- cooled condenser with a length of 400 mm is recommended. The stills and traps shall be chosen to cover the range of materials and water contents expected. If the amount of water collected is likely to exceed 25 ml, a 25 ml trap fitted with a stopcock shall be used and the excess water shall be drained off into a graduated cylinder meeting the requirements of 6.2 and 6.3.
5.2 Still, comprising a glass or metal vessel with a short neck and a suitable joint for accommodating the reflux tube of the trap. Vessels of nominal capacity 500 ml, 1 000 ml and 2 000 ml have proved satisfactory. The metal still shall be fitted with a heat-resistant gasket of material other than asbestos.
5.3 Heater, a suitable electric heater may be used with the glass still. A heater combined with a magnetic stirrer has pi-oved to be effective to avoid bumping. A gas ring burner with ports on the inside circumference shall be used with the metal still. The gas ring burner shall be of such dimensions that it can be moved up and down the vessel when testing materials that are likely to foam or solidify in the still.
6 Verification and recovery test
6.1 General
Before initial use, verily the accuracy of the trap in accordance with 6.2. Before using the apparatus, carry out a
recovery test in accordance with 6.3.
6.2 VerificatIon
Before initial use, verify the accuracy of the graduation marks on the trap by adding 0.05 ml increments of distilled water from a 5 ml microburette or a precision micropipette readable to the nearest 0,01 ml. If there is a deviation of more than 0,05 ml between the water added and water observed, reject the trap or recalibrate.
6.3 Recovery test
Before using the apparatus for a water determination, test the overall recovery of water in the entire apparatus by introducing 250 ml to 1 000 ml of dry (0.02 % water maximum) xylene. according to the size of the vessel, to the apparatus (500 ml to 2000 ml vessel as specified in 5.2) and proceed as described in clause 8. When complete, discard the contents of the trap, allow the contents of the still to cool and add the appropriate quantity of distilled water from a burette directly to the distillation flask in accordance with Table 2, and proceed as described in clause 8. The readings shall be judged accurate if the permissible limits given in Table 2 for graduated traps of different sizes are not exceeded.
A reading outside the permissible limits indicates malfunction due to vapour leaks, too rapid boiling, Of ingress of extraneous moisture. Eliminate these factors and repeat the recovery test.
7 Sampling (see annex A)
7.1 General
Sampling is defined as all steps required to obtain a representative sample of the contents of any pipe. tank or other
system and to place the sample in the laboratory test container.
7.2 Laboratory sample
Only representative samples obtained as specified in ISO 3170 and ISO 3171 shall be used in this International Standard.
The size of the test portion shall be based on the expected water content of the sample, such that the water yield does not exceed the capacity of the trap, unless a trap with a stopcock is used, since excess water can then be withdrawn into a graduated cylinder.
7.3 Preparation of the test samples
The following sample-handling procedures shall apply in addition to those covered in ISO 3170 and ISO 3171.
7.3.1 Solid samples which are sufficiently brittle shall be crushed and mixed thoroughly. A representative test portion shall be drawn from the crushed and mixed samples.
7.3.2 Liquid samples shall be mixed, after warming, if necessary, in the original container. The mixing time, mixing power (speed) and height above the bottom of the container shall be satisfactory for the product being analysed as established in the procedure given in annex A. The volume and water content of the sample shall not exceed the maximum validated in annex A.
NOTE If there is any doubt about the homogeneity of the mixed samples prepared in 7.3.1 or 7.3.2, determinatIons should be made on the total volume of the sample if the sample size is compatible with the expected water content. If this is not possible, a determination should be made on at least three test portions. All these results should be included in the test report and their average should be recorded as the water content of the sample.