ISO 2719 Determination of flash point - Pensky-Martens closed cup method
7 Apparatus preparation
7.1 General
Follow the manufacturer's instructions for the correct setup, calibration, verification and operation of the apparatus including the integral barometer (if fitted) and temperature measuring device (see Annex C), especially the operation and setting of the ignition source.

7.2 Location of the apparatus
Support the flash point apparatus on a level and steady surface in a draught-free position.

NOTE When draughts cannot be avoided, it is good practice to surround the apparatus with a shield.

The flash point apparatus may be located in a fume hood with individual air flow control, adjusted so that vapours can be withdrawn without causing air currents around the test cup during the test.

7.3 Cleaning the test cup
Wash the test cup, cover and its accessories with an appropriate cleaning solvent to remove any traces of gum or residue remaining from a previous test. Dry using a stream of clean air to ensure complete removal of the solvent used.

7.4 Apparatus assembly
Examine the test cup, the cover and other parts to ensure that they are free from signs of damage and deposits. Assemble the apparatus in accordance with Annex B.

7.5 Apparatus verification
7.5.1 Verify the correct functioning of the apparatus at least once a year by testing a certified reference material (CRM). The result obtained shall be equal to or less than R/√2 from the certified value of the CRM, where R is the reproducibility of the method as shown in Table 4.

Use the reproducibility for Procedure A (Table 4) to calculate the verification tolerance for verification materials certified for Procedures A, B or C.

It is recommended that more frequent verification checks are made using secondary working standards (SWSs).

A recommended procedure for apparatus verification using CRMs and SWSs, and the production of SWSs, is described in Annex A.

7.5.2 The numerical values obtained during the verification check shall not be used to provide a bias statement, nor shall they be used to make any correction to the flash points subsequently determined using the apparatus.

8 Sampling
8.1 Unless otherwise specified, obtain representative samples for analysis in accordance with the procedures given in ISO 3170, ISO 3171, ISO 15528 or an equivalent National Standard.

8.2 When obtaining a sample of residual fuel oil, the sample container shall be from 85 % to 95 % full. For FAME samples, a typical one litre container filled to 85 % volume is recommended. For other types of samples, the size of the container shall be chosen such that the container is not more than 85 % full or less than 50 % full prior to any sample aliquot being taken.

8.3 Erroneously high flash points can be obtained if precautions are not taken to avoid the loss of volatile material. Do not open containers unnecessarily, to prevent loss of volatile material or possible introduction of moisture. Avoid storage of samples at temperatures in excess of 30 °C. For samples for storage, ensure that the sample container is tightly closed and leak free. Do not make a transfer unless the sample temperature is at least the equivalent of 18 °C below the expected flash point.

8.4 Do not store samples in gas-permeable containers, since volatile material may diffuse through the walls of the enclosure. Samples in leaky containers are suspect and not a source of valid results.

9 Sample handling
9.1 Petroleum products
9.1.1 Sub-sampling Sub-sample at a temperature at least 18 °C below the expected flash point. Successive test portions may be taken from the same sample container. Repeat tests have been shown to be within the precision of the method when the second test portion is taken with the sample container at least 50 % filled.

IMPORTANT - Results of flash point determinations can be affected if the sample volume falls below 50 % of the container capacity.

9.1.2 Samples containing undissolved water Flash point results can be affected by the presence of water. If a sample contains undissolved water, decant a water-free aliquot prior to mixing. For certain fuel oils and lubricants, it is not always possible to decant the sample from the free water. In such cases, separate the water from the aliquot physically, prior to mixing, or, if this is not possible, test the material in accordance with ISO 3679.

9.1.3 Samples that are liquid at ambient temperature
Mix samples by gentle manual shaking prior to removal of the test portion, taking care to minimize the loss of volatile components and proceed in accordance with Clause 10.

9.1.4 Samples that are very viscous, semi-solid or solid at ambient temperature
Samples shall be heated in their containers, with lid/cap slightly loosened to avoid build-up of dangerous pressure, at the lowest temperature adequate to liquefy any solids, not exceeding 18 °C below the expected flash point, for 30 min. If the sample is then not completely liquefied, extend the heating period for additional 30 min periods as necessary. Then gently agitate the sample to provide mixing, such as orbiting the container horizontally, before transferring to the test cup. No sample shall be heated and transferred unless its temperature is more than 18 °C below its expected flash point.

IMPORTANT - Volatile vapours can escape during heating when the sample container lid/cap is too loose.

9.2 Paints and varnishes
Prepare the samples in accordance with ISO 1513.