ISO 12937:2000 pdf download

ISO 12937:2000 pdf download.Petroleum products – Determination of water -Coulometric Karl Fischer titration method.
5 Apparatus
5.1 Automatic coulometric Karl Fischer titrator, capable of meeting the requirements given in clause 8.
5.2 Non-aerating mixer, capable of meeting the homogenization requirements given in A.3.
NOTE Both insertion mixers and circulating mixers, such as those used with automatic sampling containers, are acceptable provided they comply with the principles of annex A.
5.3 Syringes, of glass, with needles of suitable length such that the tip can reach under the surface of the anolyte when inserted through the inlet-port septum. The bores of the needles used shall be kept as small as possible, but large enough to avoid problems arising from back pressure or blocking whilst sampling.
NOTE 1 Needles with bores between 0,5 mm and 0,8 mm have been found suitable.
NOTE 2 Recommended syringe sizes are
a) 10 il with a fixed needle for periodic checking of the titrator performance,
b) 1 ml or 2 ml for petroleum product samples, and
C) 10 ml for addition of the sodium dioctylsulfosuccinate solution to petroleum product samples which are not clear and bright, or which contain free water or particulate matter.
5.4 Balance, capable of weighing to ± 0,1 mg.
5.5 Volumetric flask, capacity of 100 ml.
5.6 Sealable bottles or desiccators, to hold activated molecular sieve and dried sodium dioctylsulfosuccinate.
5.7 Ovens, capable of maintaining temperatures of 105 00 to 110 00 and 200 00 to 250 00.
5.8 Cooling bath, if required, capable of meeting the requirements of 6.2.8.
5.9 Thermometer, capable of measuring the sample temperature to the nearest 1 °C.
6 Sampling and sample preparation (see annex A)
6.1 Sampling
Samples shall be drawn in accordance with ISO 3170, ISO 3171, or an equivalent national standard.
If sampling is carried out manually, use a clear borosilicate glass bottle. If an automatic technique is employed, either collect a separate sample for water determination, or treat the whole sample collected in accordance with
6.2.4.
6.2 Sample preparation
6.2.1 If the sample is not in a container suitable for visual inspection, or is opaque, then it should be treated as if it were not clear and bright (see 6.2.4). It should not be transferred to another container.
6.2.2 Immediately prior to analysis, shake the sample vigorously by hand for 30 s and then, when free from bubbles, visually inspect it. Hold the sample up to the light and examine it for haze or lack of clarity and then swirl the sample to produce a vortex and examine both the bottom of the vortex and the bottom of the sample container for water droplets and particulate matter. Record the visual clarity as clear and bright or not clear and bright. Record whether water droplets or particulate matter were, or were not, observed on swirling.
6.2.3 If the sample is both clear and bright, free from water droplets and particulate matter, proceed in accordance with clause 9.
6.2.4 If the sample is not clear and bright, or if water droplets or particulate matter were observed on swirling, proceed in accordance with 6.2.5 to 6.2.8.
NOTE The precision of this method for samples which are not clear and bright is critically dependent upon the effectiveness of the homogenization stage which is proved periodically, see normative annex A.
6.2.5 Use a clean, dry 10 ml syringe (5.3) to add a volume of sodium dioctylsulfosuccinate solution (4.4.1) as established by the procedure specified in annex A.
NOTE Correction of the sample water content for the water content of the sodium dioctylsulfosuccinate solution is not required because the latter is negligible.
6.2.6 Record the temperature of the sample in degrees Celsius immediately before mixing.
6.2.7 To ensure homogeneity, mix the sample in the original container immediately prior to analysis. The mixing time, mixing power (speed) and mixer position relative to the bottom of the container, shall be that found to be satisfactory for the material and sample size as established by the procedure given in A.3. The sample volume and water content of the sample shall not exceed the maxima validated in A.3.
6.2.8 Record the temperature of the laboratory sample in degrees Celsius immediately after mixing. The rise in temperature between this reading and the reading in 6.2.6 shall not exceed 2 °C, otherwise loss of sample light ends or loss of water may occur. If this criterion cannot be met, the sample shall be placed in a cooling bath (5.8) prior to carrying out the procedure in 6.2.6.
7 Apparatus preparation
7.1 Due to the known reaction of acetone and other ketones with Karl Fischer reagent, the use of such solvents
to dry apparatus, sample syringes, homogenizers and sample receivers, is not permitted.
7.2 Follow the manufacturer’s directions for preparation and operation of the titration apparatus.
7.3 Seal all joints and connections to the titration cell to prevent atmospheric moisture from entering.