ISO 17197 pdf download

ISO 17197 pdf download Dimethyl ether (DME) for fuels — Determination of water content — Karl Fischer titration method
Scope
This international Standard specifies a procedure oftest for the amount of water content in DME used asfuel by the Karl Fischer titration method. This procedure is applicable to determine the amount of waterup to the value specified in ISO 16861.
This testmethod is intended for use with commercially available coulometric (or volumetric) Karl Fischerreagents and forthe determination of water in DME additives, lube oils, base oils automatic transmissionfluids, hydrocarbon solvents, and other petroleum products. By proper choice of the sample size, thistest method can be used to determine water from mg/kg (ppm) to percent level concentrations.
NOTEThe precision of this method has been studied for a limited set of samples and content levels by alimited amount oflabs. lt allows establishment of a quality specification of DME but cannot be considered as a fulprecision determination in line with the usual statistical methodology as in ISO 4259.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including any amendments) applies.
ISO 29945, Refrigerated non-petroleum-based liquefied gaseous fuels — Dimethylether (DME)– Method ofmanual sampling onshore terminals
3 Principle
A gaseous sample of DME is bubbled into the titration vessel of a coulometric (or volumetric) KarFischer apparatus. The titration is then performed until all of the water has been titrated, the endpoint is detected by an electrometric end point detector, and the titration is terminated. Based on thestoichiometry ofthe reaction, 1.0 mol of iodine reacts with 1,0 mol of water; thus, the quantity of wateris proportional to the quantity of Karl Fisher reagent used.
Reagents and materials4
4.1Sample solvent, reagent grade.
Use methanol (anhydrous) with minimum purity 99,9 mass % and maximum water content 0,1 mass %(and preferably less than 0,05 mass %
This water content could be achieved by dissolving 24 g of magnesium metal turnings in 200 ml ofmethanol (the reaction could be vigorous). When the reaction is completed, add 3 of methanol. Refluxfor 5 h. Distill directly into the container in which the 999 mass % methanol is to be kept. Vent thesystem through a drying tube during the distillation.
4.2 Coulometric Karl Fischer reagent.
Use standard, commercially available reagents for coulometric Karl Fischer titrations.
4.2.1 Anode solution.
Use a standard, commercially available anode Karl Fischer solution. A newly made solution should be used.
4.2.2 Cathode solution.
Use a standard, commercially available cathode Karl Fischer solution. A newly made solution should be used.
4.3 Volumetric Karl Fischer reagent.
Use standard, commercially available, pyridine-free Karl Fischer reagents for volumetric titrations (one or two components). Use as described in 4.1.
4.3.1 One component.
Use a commercial volumetric Karl Fischer reagent. Fresh Karl Fischer reagent shall be used (alternatively,the solution should be standardized or calibrated each time it is used).