3. Summary of Test Method
3.1 After homogenizing the crude oil with a mixer, a weighed aliquot is dissolved in xylene at 65°C and extracted with specified volumes of alcohol, acetone, and water in an electrically heated extraction apparatus. A portion of the aqueous extract is analyzed for total halides by potentiometric titration.
4. Significance and Use
4.1 A knowledge of water extractable inorganic halides in oil is important when deciding whether or not the oils need desalting. Excessive halide, especially in crude oil, frequently results in higher corrosion rates in refining units.
5. Apparatus
5.1 Extraction Apparatus, made of borosilicate glass, conforming to the dimensions given in Fig. 1, and consisting of the following component parts:
5.1.1 Boiling Flask, 500 mL capacity.
5.1.2 Hopkins Reflux Condenser, having a vapor outlet connected by a rubber tube to an outside vent or to a suction hood.
5.1.3 Thistle Tube, approximately 70 mL capacity, with a line to indicate approximately the 50 mL level.
5.1.4 Heating Tube, containing a chimney for increasing convection in the liquid.
5.1.5 Heating Coil, 250 W, consisting of a suitable gage of Nichrome wire.
5.1.6 Rheostat, of suitable resistance and capacity, for regulating the heater.
5.2 Safety Shield, colorless safety glass, or equivalent, to be mounted in front of the extraction apparatus (see 5.1).
5.3 Sampling Tube, glass, length approximately 600 mm, I.D. approximately 5 mm, with a bulb having a volume of 100 mL, or more, and drawn out at one end to an opening of inside diameter (I.D.) 2 to 3 mm. A pipette with cut-off tip makes a suitable sample tube.
5.4 Potentiometric Titration Equipment, with a measuring accuracy of 6 2 mV, or better, provided with a silver indicating and a glass reference electrode and 10 mL burette, preferably piston type. If an automatic titrator is used, this shall be capable of adding fixed increments of titrant (see 9.3.3.2).
5.5 Magnetic Stirrer, with polytetrafluoroethylene (PTFE) - coated stirring bar.
5.6 Homogenizer. A mixer with counter-rotating blades operating at approximately 3000 r/min (50/s) is usually suitable for homogenization of samples up to 500 mL. Other designs can also be used provided the performance conforms to the requirements described in Annex A1.
5.7 Oven, explosion-proof, temperature 65 6 5°C.
5.8 Filter Paper, Whatman No. 41, or equivalent.
5.9 Stopwatch.
