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3、d. Nonconfidential UOP Methods are available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, USA. The UOP Methods may be obtained through the ASTM website, www.astm.org, or by contacting Customer Service at serviceastm.org, 610.832.9555 FAX, or 610.83
4、2.9585 PHONE. Color Stability of Petroleum Distillates UOP Method 793-12 Scope This method is for determining the color stability of petroleum distillates. A comparison of the ASTM Saybolt Color, D156 or D6045, as determined on the sample before and after a timed heating period, provides a direct in
5、dication of the color stability of the sample. References ASTM Method D156, “Saybolt Color of Petroleum Products (Saybolt Chromometer Method),” www.astm.org ASTM Method D6045, “Color of Petroleum Products by the Automatic Tristimulus Method,” www.astm.org Outline of Method ASTM Saybolt Color is dete
6、rmined on the sample. The sample is placed in a glass bottle at 15-25C allowing free access to air. The sample is rapidly heated to 100C in the absence of light and held at that temperature under atmospheric pressure for 20 hours. After cooling to 15-25C, the ASTM Saybolt Color is redetermined. Appa
7、ratus The apparatus listed are in addition to that required for ASTM Method D156, “Saybolt Color of Petroleum Products (Saybolt Chromometer Method),” or ASTM Method D6045, “Color of Petroleum Products by the Automatic Tristimulus Method.” References to catalog numbers are included as a convenience t
8、o the method user. Other suppliers may be used. Bottles, 250-mL, borosilicate glass, Wheaton No. 219817, VWR, Cat. No. 16159-856 Cylinder, graduated, 250-mL, Class B, VWR, Cat. No. 89000-256 Lead ring flask weights, to stabilize bottles in the bath, VWR, Cat. No. 29700-004 (optional) Oil bath (water
9、 bath), to 99.9C, digital control, with stainless steel gable cover, VWR, Cat. No. 13491-028 2 of 3 793-12 Reagents and Materials The reagents and materials listed are in addition to that required for ASTM Method D156. References to catalog numbers are included as a convenience to the method user. O
10、ther suppliers may be used. Bath fluid, heat transfer fluid, temperature range to 150 C, VWR, Cat. No. 13270-794 Procedure The analyst is expected to be familiar with general laboratory practices, the technique of chromometry, and the equipment being used. Preparation of Apparatus Place the oil bath
11、 in a fume hood that is shielded from light to avoid exposure of the samples during aging. Alternatively, a special ventilation hood may be fitted over the bath to permit free air circulation without exposure of the samples to light. Fill the bath with oil to a sufficient depth so that the oil will
12、be at or above the level of the sample when the test bottles are inserted, but not so high that the inserted bottles will float and become unstable. Lead ring flask weights may be used to prevent floatation of the bottles in the bath. Establish a temperature of 100 2C. Sample analysis 1. Determine t
13、he Saybolt Color of the sample as described in ASTM Method D156 or ASTM Method D6045. The sample may need to be filtered before measurement, see ASTM Method D156. 2. Using the 250-mL graduated cylinder, measure 120 mL of the sample to be tested into a clean, dry bottle. 3. Place the uncovered bottle
14、 into the oil bath, protect from light, and allow the fuel sample to age for 20 hours at 100 2C. 4. Remove the sample from the bath and allow it to cool to ambient temperature. 5. Determine the Saybolt Color on the cooled, heat-treated fuel sample as described in ASTM Method D156 or ASTM Method D604
15、5. The sample may need to be filtered before measurement, see ASTM Method D156. Report Report the Saybolt Color of the fuel before and after heat treatment. Precision The repeatability and reproducibility of the Saybolt Color test is listed in ASTM Method D156 and ASTM Method D6045. Repeatability an
16、d Site Precision Six replicate color stability analyses were performed on an oil sample. The estimated standard deviation was calculated at the Saybolt colors listed in the Table. Two analyses performed in one laboratory by the same analyst on the same day should not differ by more than the repeatab
17、ility allowable difference shown in the Table with 95% confidence. 3 of 3 793-12 Table Repeatability, Saybolt Color Initial Color Color Change Within-Day esd Allowable Difference +22 -7 1.7 4 The data in the Table represent short-term estimates of the repeatability of the method. When the test is ru
18、n routinely, use of a control standard and a control chart is recommended to generate an estimate of long-term repeatability. Reproducibility There is insufficient data to calculate the reproducibility of the test at this time. Time for Analysis The elapsed time for one analysis is 23 hours. The labor requirement is 1 hour. Suggested Suppliers VWR International, 1310 Goshen Parkway, West Chester, PA 19380, USA (610-431-1700)
