ISO 3733 Petroleum products and bituminous materials - Determination of water - Distillation method
4 Reagents
NOTE For the purposes of this International Standard, the expression "% (V/V)" is used to represent the volume fraction of a material.
A solvent-carrier liquid appropriate to the materials being tested (see Table 3) shall be used.
4.1 Aromatic solvent
The following aromatic solvents, free of water (0.02 % maximum) are suitable:
a) industrial grade xylene (mixed xylenes);
b) a blend of 20 % (V/V) industrial grade toluene and 80 % (V/V) industrial grade xylene (mixed xylenes);
c) petroleum distillate, yielding not more than 5 % (V/V) distillates at 125 °C and not less than 20 % (V/V) at 160 °C when tested in accordance with ISO 3405 and with a density not lower than 855 kg/m3 at 15 °C.
4.2 Petroleum distillate solvent
A petroleum solvent, free of water, of which 5 % (V/V) boils between 90 °C and 100 °C, and 90 % (V/V) distils below 210 °C.
4.3 Paraffinic solvents
The following paraffinic solvents, free of water, are suitable:
a) light petroleum with a boiling range of 100 °C to 120 °C;
b) 2,2,4-trimethylpentane ( iso -octane) of 95 % purity or better.
5 Apparatus
5.1 General
The apparatus comprises 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 O-rings for metal to glass. Typical assemblies 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 results 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, 1000 ml and 2000 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 proved 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.
