ASTM D1322 Test Method for Smoke Point of Kerosine and Aviation Turbine Fuel
11. Procedure
11.1 Soak a piece of extracted and dried wick, not less than 125 mm long, in the sample and place it in the wick tube of the candle. Carefully ease out any twists arising from this operation. In cases of dispute, or of referee tests, always use a new wick, prepared in the manner specified in 9.2.
NOTE 8 - It is advisable to resoak the burning-end of the wick in the sample after the wick is inserted in the wick tube.
11.2 Introduce as near to 20 mL of the prepared sample as available, but not less than 10 mL, at room temperature, into the clean, dry candle.
11.3 Place the wick tube in the candle and screw home. Take care that the candle air vent is free from fuel. If a wick-trimmer assembly is not being used, cut the wick horizontally and trim it free of frayed ends so that 6 mm projects from the end of the candle. Use a clean razor blade or other sharp instrument. (Some razor blades have a protective coating; in such cases, remove the coating with a solvent before using the blade). Insert the candle into the lamp.
11.3.1 An alternative method of preparing a wick free of twists and frayed ends utilizes a wick-trimmer assembly. The wick-trimmer holder is inserted over the top of the wick tube and the long-nosed triceps are inserted through the tube and holder. The wick is grasped and carefully pulled through the tube without twisting. A new, clean, sharp razor is used to cut the wick at the face of the holder and remove wisps and frayed ends. When the holder is removed, the wick will be at the correct height in the tube. The tube is then inserted into the candle and screwed home. The candle is inserted into the lamp.
11.4 Light the candle and adjust the wick so that the flame is approximately 10 mm high and allow the lamp to burn for 5 min. Raise the candle until a smoky tail appears, then lower the candle slowly through the following stages of flame appearance:
11.4.1 A long tip; smoke slightly visible; erratic and jumpy flame.
11.4.2 An elongated, pointed tip with the sides of the tip appearing concave upward as shown in Fig. 2 (Flame A).
11.4.3 The pointed tip just disappears, leaving a very slightly blunted flame as shown in Fig. 2 (Flame B). Jagged, erratic, luminous flames are sometimes observed near the true flame tip; these shall be disregarded.
11.4.4 A well rounded tip as shown in Fig. 2 (Flame C). Determine the height of Flame B to the nearest 0.5 mm. Record the height observed.
11.4.4.1 To eliminate errors due to parallax, the eye of the observer shall be slightly to one side of the centreline, so that a reflected image of the flame is seen on the scale on one side of the central vertical white line, and the flame itself is seen against the other side of the scale. The reading for both observations shall be identical.
11.5 Make three separate observations of the flame height at the smoke point by repeating the flame-appearance sequence specified in 11.4. If these values vary over a range greater than 1.0 mm, repeat the test with a fresh sample and another wick.
11.6 Remove the candle from the lamp, rinse with heptane, and purge with air to make ready for re-use.
12. Calculation
12.1 Calculate the smoke point, to the nearest 0.1 mm, from the equation:
smoke point = L x f
where:
L = the average, rounded to the nearest 0.1 mm, of three individual readings, and
f = the correction factor (see 10.2), rounded to the nearest 0.01.
12.2 Record the result thus obtained, rounded to the nearest 0.5 mm, as the smoke point of the sample.
