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D86_10 (17)

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Record the prevailing barometric pressure. Groups 1 and 2. Ensure that the sample is conditioned in accordance with Table 2 of the written standard. Fit a low-range thermometer provided with a snug-fitting cork or stopper of silicone rubber or equivalent polymetric material tightly into the neck of the sample container, and bring the temperature of the sample to the temperature indicated in Table 3 of the written standard. Check that the temperature of the sample is as shown in Table 3 of the written standard. Pour the specimen precisely to the 100 milliliter mark of the receiving cylinder, and transfer the contents of the receiving cylinder as completely as practical into the distillation flask, ensuring that none of the liquid flows into the vapor tube. It is important that the difference between the temperature of the specimen and the temperature of the bath around the receiving cylinder is as small as practically possible. A difference of 5 degrees Celsius can make a difference of 0.7 milliliters. If the sample is not fluid at ambient temperature, it is to be heated to a temperature between 9 and 21 degrees Celsius above its pour point, Test Methods D97, D5949, D5950, or D5985, prior to analysis. If the sample has partially or completely solidified in the intervening period, it shall be vigorously shaken after melting and prior to sampling to ensure homogeneity. If the sample is not fluid at ambient temperatures, disregard the temperature range shown in Table 3 of the written standard for the receiving cylinder and sample. Prior to analysis, heat the receiving cylinder to approximately the same temperature as the sample. Pour the heated specimen precisely to the 100 milliliter mark of the receiving cylinder, and transfer the contents of the receiving cylinder as completely as practical into the distillation flask, ensuring that none of the liquid flows into the vapor tube. Any material that evaporates during the transfer will contribute to the loss. Any material that remains in the receiving cylinder will contribute to the observed recovery volume at the time of the IBP, or Initial Boiling Point. If the sample can be expected to demonstrate irregular boiling behavior, that is, bumping, add a few boiling chips to the specimen. The addition of a few boiling chips is acceptable for any distillation. Fit the temperature sensor through a snug-fitting device as described in 6.4 of the written standard to mechanically center the sensor in the neck of the flask. In the case of the thermometer, the bulb is centered in the neck, and the lower end of the capillary is level with the highest point on the bottom of the inner wall of the vapor tube. In the case of a thermocouple or resistance thermometer, follow the manufacturer's instructions as to placement. If vacuum grease is used on the mating surface of the centering device, use the minimum amount of grease that is practical. Fit the flask vapor tube provided with a snug-fitting cork or rubber stopper of silicone or equivalent polymetric material tightly into the condenser tube. Adjust the flask in a vertical position so that the vapor tube extends into the condenser tube for a distance from 25 to 50 millimeters. Raise and adjust the flask support board to fit it snugly against the bottom of the flask. Place the receiving cylinder that was used to measure the specimen without drawing the inside of the cylinder into its temperature-controlled bath under the lower end of the condenser tube. The end of the condenser tube shall be centered in the receiving cylinder and shall extend therein for a distance of at least 25 millimeters, but not below the 100 millimeters mark. To reduce evaporation loss of the distillate, cover the receiving cylinder with a piece of blotting paper or similar material that has been cut to fit the condenser tube snugly. If a receiver deflector is being used, start the distillation with the tip of the deflector just touching the wall of the receiving cylinder. If a receiver deflector is not used, keep the drip tip of the condenser away from the wall of the receiving cylinder. Note the start time. Observe and record the IBP to the nearest 0.5 degrees Celsius, or 1.0 degrees Fahrenheit. If a receiver deflector is not being used, immediately move the receiving cylinder so that the tip of the condenser touches its inner wall. To reduce evaporation loss of the distillate, use the device provided by the instrument manufacturer for this purpose. Apply heat to the distillation flask and contents with the tip of the receiver deflector just touching the wall of the receiving cylinder. Note the start time. Record the IBP, or Initial Boiling Point, to the nearest 0.1 degree Celsius or 0.2 degrees Fahrenheit. Regulate the heating so that the time interval between the first application of heat and the IBP is as specified in Table 5 of the written standard. Regulate the heating so that the time from IBP to 5% recovered is as indicated in Table 5 of the written standard. Continue to regulate the heating so that the uniform average rate of condensation from 5% recovered to 5 millimeters residue in the flask is 4 to 5 milliliters per minute. Warning. Due to the configuration of the boiling flask and the conditions of the test, the vapor and liquid around the temperature sensor are not in thermodynamic equilibrium. The distillation rate will consequently have an effect on the measured vapor temperature. The distillation rate shall, therefore, be kept as constant as possible throughout the test. In context of this method, uniform average rate of condensation has the following intention. Heating of the boiling flask shall be regulated to maintain as best as possible a uniform flow of condensation, which will then provide the most desired precision for the test. However, some distillation tests can have one or more short-term rates of condensation which deviate from the 4 milliliters per minute to 5 milliliters per minute indicated in 10.11 and Table 5 of the written standard. This is a common occurrence for some sample types. The periods of these short-term deviations may last for several percent of material condensed until the temperature slope becomes constant again and may occur at several periods along the entire condensation range. These deviations will typically correct after the temperature slope again becomes constant. These short-term deviations shall not occur over the entire range of condensation. Typically, these short-term deviations should not occur for more than 10 contiguous percent volume. The precision of the temperature readings shall be significantly affected during these periods. When the overall calculated average rate of condensation between 5% recovered and 5 milliliter residue is within the prescribed rate, the requirement of 10.11 and Table 5 of the written standard is satisfied. As example, those samples containing a 10% ethanol fuel blend or those that exhibit a significant change of temperature slope at points during the distillation can have a short-term rate of condensation which deviates from the 4 milliliters per minute to 5 milliliters per minute minute indicated in 10.11 and Table 5 of the written standard. When testing gasoline samples, it is not uncommon to see the condensate suddenly form non-miscible liquid phases and beat up on the temperature measuring device and in the neck of the boiling flask at a vapor temperature of around 160 degrees Celsius. This may be accompanied by a sharp, about 3 degrees Celsius dip in the vapor temperature and a drop in the recovery rate. The phenomenon, which may be due to the presence of trace water in the sample, may last for 10 to 30 seconds before the temperature recovers and the condensate starts flowing smoothly again. This point is sometimes colloquially referred to as the hesitation point. Repeat any distillation that did not meet the requirements described in 10.9, 10.10, and 10.11 of the written standard. If a decomposition point is observed, discontinue the heating and proceed as directed in 10.17. Characteristic indications of thermal decomposition are evaluation of fumes and erratic, typically decreasing temperature readings that occur during the final stages of the distillation. In the interval between the IBP, Initial Boiling Point, and the end of the distillation, observe and record data necessary for the calculation and reporting of the results of the test as required by the specification involved, or as previously established for the sample under test. These observed data can include temperature readings at prescribed percentages recovered or percentages recovered at prescribed temperature readings or both. Record all volumes in the graduated cylinder to the nearest 0.5 milliliters and all temperature readings to the nearest 0.5 degrees Celsius or 1.0 degrees Fahrenheit. Record all volumes in the receiving cylinder to the nearest 0.1 milliliters and all temperature readings to the nearest 0.1 degree Celsius or 0.2 degrees Fahrenheit. In cases in which no specific data requirements have been indicated, record the IBP and the EP, End Point, or FBP, Final Boiling Point, or the dry point, or both, and temperature readings at 5%, 15%, 85% and 95% recovered and at each 10% multiple of volume recovered from 10 to 90 inclusive. When a high-range thermometer is used in testing aviation turbine fuels and similar products, pertinent thermometer readings can be obscured by the centering device. If these readings are required, perform a second distillation in accordance with group 3. In such cases, reading from a low-range thermometer can be reported in place of the obscured high-range thermometer readings, and the test report shall so indicate. If, by agreement, the obscured readings are waived, the test report shall so indicate. When it is required to report the temperature reading at a prescribed percent evaporated or recovered for a sample that has a rapidly changing slope of the distillation curve in the region of the prescribed percent evaporated or recovered reading, record temperature readings at every 1% recovered. The slope is considered rapidly changing if the change in slope, c, of the data points described in 10.14.2 of the written standard in that particular area is greater than 0.6 change of slope, f, is greater than 1.0 as calculated by Equation 1, Equation 2 of the written standard. When the residual liquid in the flask is approximately 5 milliliters, make a final adjustment of the heat. The time from the 5 milliliters of liquid residue in the flask to the EP FBP shall be within the limits prescribed in Table 5 of the written standard. If this condition is not satisfied, repeat the test with appropriate modification of the final heat adjustment. Since it is difficult to determine when there is 5 milliliters of boiling liquid left in the flask, this time is determined by observing the amount of liquid recovered in the receiving cylinder. The dynamic holdup has been determined to be approximately 1.5 milliliters at this point. If there are no front-end losses, the amount of 5 milliliters in the flask can be assumed to correspond with an amount of 93.5 milliliters in the receiving cylinder. This amount has to be adjusted for the estimated amount of front-end loss. If the actual front-end loss differs more than two milliliters from the estimated value, the test shall be rerun. Observe and record the EP, FBP, or the dry point, or both as required, and discontinue the heating. The end point, final boiling point, rather than the dry point, is intended for general use. The dry point can be reported in connection with special purpose naphthas, such as those used in the paint industry. Also, it is substituted for the end point, final boiling point, whenever the sample is of such a nature that the precision of the end point, final boiling point, cannot consistently meet the requirements given in the precision section. Once the final heat adjustment is made, the vapor temperature and thermometer reading will continue to increase as the distillation nears the end point. As the distillation nears the end point, final boiling point, the distillation typically achieves dry point first. After the dry point has been achieved, the vapor temperature and thermometer reading should continue to increase. The bottom of the flask will be dry, but the sides and neck of the flask and the temperature sensor will still have vapor condensate present. The vapor condensate may have the appearance of a white cloud of fumes. This vapor condensate and cloud of fumes should totally engulf the temperature measuring sensor before the vapor temperature starts to decrease. If these observations do not occur, the end point may not have been reached. It would be advisable to repeat the test adding additional heat to the final heat adjustment. Typically, the vapor temperature will continue to rise as the dry point is reached and the vapor cloud engulfs the temperature measuring sensor. When the end point is near, the rate of temperature increase will slow and level off. Once the end point is reached, the vapor temperature will start and continue to decrease. If the vapor temperature starts to decrease but then increases and repeats this cycle while the vapor temperature continues to increase, you have added too much heat to the final heat adjustment. If this is the case, it would be advisable to repeat the test lowering final heat setting. Many Group 3 and 4 samples will have the same distillation characteristics in regards to dry point and end point as Groups 1 and 2. With samples that contain higher temperature boiling materials, it may not be possible to detect a dry point or an end point before the decomposition point occurs. Allow the distillation to drain into the receiving cylinder after heating has been discontinued. While the condenser tube continues to drain into the graduated cylinder, observe and note the volume of condensate to the nearest 0.5 milliliters at two-minute intervals until two successive observations agree. Measure the volume in the receiving cylinder accurately and record it to the nearest 0.5 milliliters. The apparatus shall continually monitor the recovered volume until this volume changes by no more than 0.1 milliliters in two minutes. Record the volume in the receiving cylinder accurately to the nearest 0.1 milliliter. Record the volume in the receiving cylinder as percent recovery. If the distillation was previously discontinued under the conditions of a decomposition point, deduct the percent recovered from 100. Report this difference as the sum of percent residue and percent loss and omit the procedure given in 10.19 of the written standard. After the flask has cooled and no more vapor is observed, disconnect the flask from the condenser, pour its contents into a 5 milliliter graduated cylinder and, with the flask suspended over the cylinder, allow the flask to drain until no appreciable increase in the volume of liquid in the cylinder is observed. Measure the volume in the graduated cylinder to the nearest 0.1 milliliters and record as percent residue. If the 5 milliliter graduated cylinder does not have graduations below 1 milliliter and the volume of liquid is less than 1 milliliter, pre-fill the cylinder with 1 milliliter of heavy oil to allow a better estimate of the volume of the material recovered. If a residue greater than expected is obtained and the distillation was not purposely terminated before the EP, check whether adequate heat was applied towards the end of the distillation and whether conditions during the test conformed to those specified in Table 5 of the written standard. If not, repeat test. The distillation residues of this test method for gasoline, kerosene, and distillate diesel are typically 0.9 to 1.2, 0.9 to 1.3, and 1.0 to 1.4 volume percent, respectively. The test method is not designed for the analysis of distillate fuels containing appreciable quantities of residual material. See 1.2 of the written standard. Record the volume in the 5 milliliter graduated cylinder to the nearest 0.1 milliliter as percent residue. If the intent of the distillation is to determine the percent evaporated or percent recovered at the pre-determined corrected temperature reading, modify the procedure to conform to the instructions described in Annex A4 of the written standard. Examine the condenser tube and the sidearm of the flask for waxy or solid deposits. If found, repeat the test after making adjustments described in Footnote A of Table 5 of the written standard.

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Posted by: abuckmaster on Jul 17, 2018

D86_10 (17)

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