ISO 3016 Petroleum products - Determination of pour point
6 Procedure
6.1 Pour the sample into the test jar to the level mark. If necessary, heat the sample in a water bath until it is just sufficiently fluid to pour into the test jar.
If it is necessary to heat the sample to a temperature greater than 45 °C to effect the transfer to the test jar, or when it is known that a sample has been heated to a temperature higher than 45 °C during the preceding 24 h, or when the thermal history of the sample is not known, keep the Sample at room temperature for 24 h before testing it.
6.2 Close the test jar (5.1) with the cork (5.3) carrying the high-cloud-and-pour thermometer or, if the expected pour point is above 36 °C, the melting point thermometer (annex A). Adjust the position of the cork and thermometer so that the cork fits tightly, the thermometer and the test jar are coaxial, and the thermometer bulb is immersed to a depth which places the beginning of the capillary 3 mm below the surface of the sample.
6.3 Subject the sample in the test jar to a preliminary treatment, appropriate to its pour Point, in accordante with 6.4 or 6.5.
6.4 Samples having pour Points above -33 °C shall be treated as follows.
6.4.1 Heat the sample without stirring to 9 °C above the expected pour Point, or to 45 °C, whichever is greater, in a bath maintained at 12 °C above the expected pour Point, but at least 48 °C.
6.4.2 Transfer the test jar to a bath maintained at 24 °C +/- 1.5 °C.
6.4.3 When the sample temperature reaches 9 °C above the expected pour point (estimated as a multiple of 3 °C), commence observations for flow in accordante with 6.7.
6.4.4 If the sample has not ceased to flow when the temperature has reached 27 °C, carefully remove the test jar from the bath, wipe the outside surface with a clean cloth moistened with wiping fluid (4.5), and place it in the 0 °C bath (5.7) in accordance with 6.6. Make observations for flow in accordance with 6.7 and cool as specified in the schedule given in 6.8.
6.5 Samples having pour points of -33 °C and below shall be treated as follows.
6.5.1 Heat the sample without stirring to 45 °C in a bath maintained at 48 °C, and cool to 15 °C in a bath maintained at 6 °C +/- 1.5 °C.
6.5.2 When the temperature has reached 15 °C, carefully remove the test jar from the water bath, wipe the outside surface with a clean cloth moistened with wiping fluid (4.5), remove the high-cloud-and-pour thermometer and replace it with the low-cloud-and-pour thermometer (annex A). Place the test jar in the 0 °C bath (6.7) in accordance with 6.6. Successively place the test jar into lower-temperature baths in accordance with the schedule specified in 6.8.
6.5.3 When the temperature reaches 9 °C above the expected pour point, commence observations for flow in accordance with 6.7.
6.6 Ensure that the disc (5.5), gasket (5.6) and the inside of the jacket (5.4) are clean and dry, and place the disc in the bottom of the jacket. The disc and jacket shall have been placed in the cooling medium (see 5.7) a minimum of 10 min before the test jar is inserted. Place the gasket around the test jar approximately 25 mm from the bottom, and insert the test jar into the jacket. With the exception of the baths at 24 °C and 6 °C, never place a test jar directly into the cooling medium.
6.7 Carry out observations for flow.
6.7.1 At each thermometer reading that is a multiple of 3 °C below the temperature of the first observation, remove the test jar from the bath or jacket, as applicable, and tilt it just sufficiently to ascertain whether there is movement in the sample in the test jar. The complete operation of test jar removal, observation of the sample for flow, and return of the test jar to the bath shall not exceed 3 s.
6.7.2 Continue observations at each thermometer reading that is a multiple of 3 °C below the temperature of the first observation.
Take great care not to disturb the mass of sample or to permit the thermometer to shift in the sample after the sample has cooled sufficiently to allow for the formation of wax crystals, as any disturbance of the spongy network of wax crystals will lead to low and erroneous results.
NOTE 4 At low temperatures, condensed moisture may limit visibility. This tan be removed by wiping the outside surface of the test jar with a clean cloth moistened with wiping fluid (4.5) close to the bath temperature.
6.7.3 As soon as the sample does not flow when tilted, hold the test jar in a horizontal position for 5 s, as measured by the timing device (5.8), and observe carefully. If the sample shows any movement, replace the test jar immediately in the bath or jacket, as applicable, and repeat the Observation at the next temperature, 3 °C lower.
6.7.4 Continue in this manner until a temperature is reached when the sample shows no movement when the test jar is held in a horizontal position for 5 s. Record the observed reading of the thermometer.
6.8 If the Sample has not ceased to flow when its temperature has reached 9 °C, transfer it to the next lower temperature bath, and similarly at -6 °C, -24 “C and -42 °C in accordance with the following schedule:
a) Sample is at +9 °C, move to -18 °C bath;
b) Sample is at -6 °C, move to -33 °C bath;
c) Sample is at -24 °C, move to -51 °C bath;
d) Sample is at -42 °C, move to -69 °C bath.
6.9 To determine compliance with existing obsolescent specifications having pour-point limits at temperatures not divisible by 3 °C, it is acceptable practice to conduct the pour-point measurement according to the following schedule.
Begin to examine the appearance of the sample when the temperature of the sample is 9 °C above the specification pour point. Continue observations at 3 °C intervals in accordance with 6.7 and 6.8 until the specification temperature is reached. Report the sample as passing or failing the specification limit.
6.10 For fuel oils, heavy lubricant base stock and products containing residual fuel components, the result obtained by the procedure given in 6.1 to 6.8 is the upper (maximum) pour point. If required, determine the lower (minimum) pour point by heating the sample while stirring to 105 °C, pouring it into the jar, and determining the pour Point as given in 6.2 to 6.8.
6.11 If automatic testing instruments are used, the user shall ensure that all of the manufacturer's instructions for calibration, adjustment and operation of the instrument are followed. As the precision of automatic pour-point testers has not been determined, in any case of dispute, the pour point shall be determined by the manual method described herein and shall be considered as the reference test.