7. Sampling
7.1 Erroneously high flash points will be obtained when precautions are not taken to avoid the loss of volatile material. Containers should not be opened unnecessarily to prevent loss of volatile material and possible introduction of moisture. Transfers should not be made unless the sample temperature is at least 10°C (18°F) below the expected flash point. When possible, flash point shall be the first test performed on a sample and the sample must be stored at low temperature.
7.2 Do not store samples in gas-permeable containers since volatile materials may diffuse through the walls of the enclosure. Samples in leaky containers are suspect and not a source of valid results.
7.3 At least 50 mL of sample is required for each test. Refer to sampling information in Practice D 4057.
8. Preparation of Apparatus (Manual)
8.1 Support the manual apparatus on a level steady surface, such as a table. Unless tests are made in a draft-free room or compartment, surround the tester on three sides by the shield for protection from drafts. Tests are not to be made in a laboratory draft hood or near ventilators.
8.2 Natural gas and bottled gas flame and electric ignitors have been found acceptable for use as the ignition source. (Warning - Gas pressure supplied to the apparatus must not be allowed to exceed 3 kPa (12 in.) of water pressure.)
8.3 Forflash points below 13°C (55°F) or above 60°C (140°F), use as a bath liquid a 1 + 1 mixture of water and ethylene glycol (Warning - Ethylene Glycol - Poison. Harmful or fatal if swallowed. Vapor harmful. Avoid contact with skin.) For flash points between 13°C (55°F) and 60°C (140°F), either water or a water-glycol mixture can be used as bath liquid. The temperature of the liquid in the bath shall be at least 10°C (18°F) below the expected flash point at the time of introduction of the sample into the test cup. Do not cool bath liquid by direct contact with dry ice (solid carbon dioxide).
NOTE 3 - Due to possible difficulty in maintaining the prescribed rate of temperature rise and due to the formation of ice on the lid, results by this test method for samples having flash points below 0°C (32°F) may be unreliable. Trouble due to ice formation on the slide can be minimized by carefully lubricating the slide shutter with high-vacuum silicone lubricant.
8.4 Verify the performance of the manual apparatus (or in 11.2.3, the automated apparatus) at least once per year by determining the flash point of a certified reference material (CRM), such as those listed in Annex A2, which is reasonably close to the expected temperature range of the samples to be tested. The material shall be tested according to the procedure of this test method and the observed flash point obtained in 9.5 shall be corrected for barometric pressure (see Section 13). The flash point obtained shall be within the limits stated in Table A2.1 for the identified CRM or within the limits calculated for an unlisted CRM (see Annex A2).
8.5 Once the performance of the apparatus has been verified, the flash point of secondary working standards (SWSs) can be determined along with their control limits. These secondary materials can then be utilized for more frequent performance checks (see Annex A2).
8.6 When the flash point obtained is not within the limits stated in 8.4 or 8.5, check the condition and operation of the apparatus to ensure conformity with the details listed in Annex A1, especially with regard to tightness of the lid (see A1.1.3), the action of the shutter, the position of the ignition source (see A1.1.3.3), and the angle and position of the temperature measuring device (see A1.1.3.4). After any adjustment, repeat the test in 8.4 using fresh test specimen, with special attention to the procedural details prescribed in the test method.
