ISO 2719 Determination of flash point - Pensky-Martens closed cup method
10 Procedure
10.1 General
10.1.1 The applicability of the three procedures A, B and C is explained in Clause 1.

Electronic flash point detection shall be used for procedure C, as it is difficult to observe a flash by visual means, and may be used for procedures A and B.

10.1.2 Care should be taken when testing samples of residual fuel oil that contain significant amounts of water, as heating these samples can cause them to foam and eject from the test cup.

10.1.3 As a safety practice, it is strongly advised to apply the ignition source to the test portion in the cup before heating the test cup and test portion, to check for the presence of unexpected volatile material.

10.1.4 As a safety practice, it is strongly advised that, for an expected flash point above 130 °C, to dip the ignition source every 10 °C throughout the test until the sample temperature reaches 28 °C below the expected flash point and then follow the prescribed dipping procedure. This practice has been shown to reduce the possibility of a fire and not to significantly affect the result.

10.1.5 At the end of a test, when the apparatus has cooled down to a safe handling temperature, remove the test cover and the test cup and clean the apparatus as recommended by the manufacturer.

10.2 Procedure A
10.2.1 Record the laboratory absolute barometric pressure reading at the time of test (see 6.3).

It is not necessary to correct the barometric pressure to 0 °C, although some barometers are designed to make this correction automatically.

10.2.2 Fill the test cup (see 7.3) with the test portion to the level indicated by the filling mark. Place the lid on the test cup and put them in the heating chamber. Ensure that the locating or locking device is properly engaged and insert the temperature measuring device. Light the test flame and adjust to a diameter of 3,2 mm to 4,8 mm or enable the alternative ignition source. Supply heat at such a rate that the temperature of the test portion, as indicated by the temperature measuring device, increases at 5,0 °C/min to 6,0 °C/min, and maintain this heating rate throughout the test. Stir the test portion at a rotational rate of 90 r/min (1,5 Hz) to 120 r/min (2,0 Hz), stirring in a downward direction.

10.2.3 When the test portion is expected to have a flash point of 110 °C or below, make the first application of the ignition source when the temperature of the test portion is 23 °C +/- 5 °C below the expected flash point, and thereafter at 1 °C temperature intervals. Cease stirring and apply the ignition source by operating the mechanism on the cover, that controls the shutter and ignition source, so that the source is lowered into the vapour space of the test cup in 0,5 s, left in its lowered position for 1 s, and quickly raised to its high position.

10.2.4 When the test portion is expected to have a flash point of above 110 °C, make the first application of the ignition source when the temperature of the test portion is 23 °C +/- 5 °C below the expected flash point, and thereafter at temperatures that are a multiple of 2 °C. Cease stirring and apply the ignition source by operating the mechanism on the cover, that controls the shutter and ignition source, so that the source is lowered into the vapour space of the test cup in 0,5 s, left in its lowered position for 1 s, and quickly raised to its high position.

10.2.5 When testing a material of unknown flash point, conduct a preliminary test at a suitable starting temperature. Make the first ignition source application at 5 °C above the starting temperature and follow the procedure given in 10.2.3 or 10.2.4, as applicable.

10.2.6 Record, as the detected flash point, the temperature of the test portion read on the temperature measuring device at the time when ignition source application causes a distinct flash in the interior of the test cup. Do not confuse the true flash point with the bluish halo that sometimes surrounds the ignition source at applications preceding the actual flash point.

10.2.7 When a flash point is detected on the first application, the test shall be discontinued, the result discarded, and the test repeated with a fresh test portion. The first application of the ignition source with the fresh test portion is recommended to be approximately 23 °C below the temperature at which a flash point was detected on the first application.

10.2.8 When the temperature at which the flash point is detected is less than 18 °C or greater than 28 °C from the temperature of the first application of the ignition source, the result shall be considered approximate. Repeat the test using a fresh test portion, adjusting the temperature of the first application of the ignition source until a valid determination is obtained, that is where the flash point is 18 °C to 28 °C above the temperature of the first application of the ignition source.

10.3 Procedure B
10.3.1 Record the laboratory absolute barometric pressure at the time of test (see 10.2.1).

10.3.2 Fill the test cup (see 7.3) with the test portion to the level indicated by the filling mark. Place the lid on the test cup and put them in the heating chamber. Ensure that the locating or locking device is properly engaged and insert the temperature measuring device. Light the test flame and adjust to a diameter of 3,2 mm to 4,8 mm or enable the alternative ignition source. Supply heat at such a rate that the temperature of the test portion as indicated by the temperature measuring device increases at 1,0 °C/min to 1,5 °C/min, and maintain this heating rate throughout the test. Stir the test portion at a rotational rate of (250 +/- 10) r/min, stirring in a downward direction.

10.3.3 When the test portion is expected to have a flash point of 110 °C or below, make the first application of the ignition source when the temperature of the test portion is 23 °C +/- 5 °C below the expected flash point, and thereafter at 1 °C temperature intervals. Cease stirring and apply the ignition source by operating the mechanism on the cover, that controls the shutter and ignition source, so that the source is lowered into the vapour space of the test cup in 0,5 s, left in its lowered position for 1 s, and quickly raised to its high position.

10.3.4 When the test portion is expected to have a flash point of above 110 °C, make the first application of the ignition source when the temperature of the test portion is 23 °C +/- 5 °C below the expected flash point, and thereafter at temperatures that are a multiple of 2 °C. Cease stirring and apply the ignition source by operating the mechanism on the cover, that controls the shutter and ignition source, so that the source is lowered into the vapour space of the test cup in 0,5 s, left in its lowered position for 1 s, and quickly raised to its high position.

10.3.5 When testing a material of unknown flash point, conduct a preliminary test at a suitable starting temperature. Make the first ignition source application at 5 °C above the starting temperature and follow the procedure given in 10.3.3 or 10.3.4, as applicable.

10.3.6 Record, as the detected flash point, the temperature of the test portion read on the temperature measuring device at the time when ignition source application causes a distinct flash in the interior of the test cup. Do not confuse the true flash point with the bluish halo that sometimes surrounds the ignition source at applications preceding the actual flash point.

10.3.7 When a flash point is detected on the first application, the test shall be discontinued, the result discarded, and the test repeated with a fresh test portion. The first application of the ignition source with the fresh test portion is recommended to be approximately 23 °C below the temperature at which a flash point was detected on the first application.

10.3.8 When the temperature at which the flash point is detected is less than 18 °C or greater than 28 °C from the temperature of the first application of the ignition source, the result shall be considered approximate. Repeat the test using a fresh test portion, adjusting the temperature of the first application of the ignition source until a valid determination is obtained, that is where the flash point is 18 °C to 28 °C above the temperature of the first application of the ignition source.

10.4 Procedure C
10.4.1 Record the laboratory absolute barometric pressure at the time of test (see 10.2.1).

10.4.2 Fill the test cup (see 7.3) with the test portion to the level indicated by the filling mark. Place the lid on the test cup and put it in the heating chamber. Ensure that the locating or locking device is properly engaged and insert the temperature measuring device. Light the test flame and adjust to a diameter of 3,2 mm to 4,8 mm, or enable the alternative ignition source. Supply heat at such a rate that the temperature of the test portion as indicated by the temperature measuring device increases at 2,5 °C/min to 3,5 °C/min, and maintain this heating rate throughout the test. Stir the test portion at a rotational rate of 90 r/min to 120 r/min, stirring in a downward direction.

10.4.3 Use an expected flash point of 100 °C for the first test on the sample.

10.4.4 Make the first application of the ignition source when the temperature of the test portion is approximately 24 °C below the expected flash point and each time thereafter at a temperature reading that is a multiple of 2 °C. Cease stirring and apply the ignition source by operating the mechanism on the cover, that controls the shutter and ignition source, so that the source is lowered into the vapour space of the test cup in 0,5 s, left in its lowered position for 1 s, and quickly raised to its high position.

10.4.5 Record as the detected flash point the temperature of the test portion read on the temperature measuring device at the time when the ignition source application causes a distinct flash in the interior of the test cup.

10.4.6 When a flash point is detected on the first application, the test shall be discontinued, the result discarded, and the test repeated with a fresh test portion. The first application of the ignition source with the fresh test portion is recommended to be approximately 24 °C below the temperature at which a flash point was detected on the first application.

10.4.7 When the temperature at which the flash point is detected is less than 16 °C or greater than 30 °C from the temperature of the first application of the ignition source, the result shall be considered approximate. Repeat the test using a fresh test portion, adjusting the temperature of the first application of the ignition source until a valid determination is obtained, that is where the flash point is 16 °C to 30 °C above the temperature of the first application of the ignition source.