ISO 12937 pdf download – Petroleum products -Determination of water – Coulometric Karl Fischer titration method.
5 Apparatus
5.1 Automatic coulonietric Karl Fischer titrator. capable of meeting the requirements given in clause 8.
52 Non-aerating mixer, capable of meeting the homogenization requirements given in k3.
NOTE Both insertion mixers and cwculating mixers, such as those used nith automatic sampng containers are acceptable provided they comply with the principles of annex A
5.3 Syringes, of glass, with needles of suitable lenglh such that the tip can reach under the surface ot the anolyte when inserted through the inlet-port septum. The bores of the needles used shall be kept as smal as possible, but large enough to avoid problems arising I ram back pressure or blocking whilst sampling.
NOTE I Needles with bores between 0.5 nvn and 0,8 ryan have been found suitable, NOTE 2 Recommended synnge sizes are
a) 10 p1 with a fixed needle for periodic checking 01 the fiirator performance.
b) 1 ml or 2 iN ler petroleum product samples, and
C) 10 ml for addlion of the sodlim dioctylsulfosuconate solution to petroletsn product sanles which are not clear and bright, or which contain tree waler or particAate matter.
5.4 Balance, capable of weighing to 0.1 mg.
5.5 VolumetrIc flask, capacity of 100 ml.
5.6 Sealable bottles or deslccators, to hold activated molecular sieve and dried sodium dioctylsulfosuccinate.
5.7 Ovens, capable of maintaining temperatures of 105 C to 110 C and 200 C to 250 C.
5.8 CoolIng bath. if required, capable 01 meeting the requirements cit 6.2.8.
5.9 Thermometer, capable of measuring the sample temperature to the nearest I iC.
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). Ii should not be transferred to another container.
6.2.2 Immediately prior to analysis, shake the sample vigorously by hand for 30s and then, when free from bubbles, visually inspect it. Hold the sample L4 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 It the sample Is both clear and bright, free from water droplets and particuLate matter, proceed In accordance with clause 9,
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 62.6 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 proceckire 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 manufacturers 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.
7.4 If a single Karl Fischer solution (4.3.3) is used, add this solution to the cell
7.5 It separate electrolyte solutions are used, add the anolyte (4.3.1) to the outer compartment of the titration cell to the level recommended by the manufacturer. Add the catholyte (4.3,2) to the inner compartment of the titration cell to a level 2mm to 3 mm below the level at the anolyte.
7.6 Turn on the titrator and stirrer. Allow the residual moisture in the titration cell to be titrated until the end-pont Is reached. Do not proceed beyond this stage until the background current (or background titration rate) is constant and less than the maximum recommended by the manufacturer of the instrument (see the note below).
ISO 12937 pdf download – Petroleum products -Determination of water – Coulometric Karl Fischer titration method
