ASTM D2472 Standard Specification for Sulfur Hexafluoride
4. Sampling
4.1 Withdraw a sample of sulfur hexafluoride from either the vapor space or liquid phase of the container.
4.2 For samples collected from the liquid phase the user must ascertain whether or not the cylinder valve is attached to a dip tube. Sample cylinders equipped with a dip tube in an upright position. Invert cylinders not equipped with a dip tube for sampling to ensure that the sample is obtained from the liquid phase of the cylinder.
4.3 Analyses may be performed on vapor space samples for routine or preliminary testing. If the vapor phase analysis indicates that impurities are not within specification, a liquid phase sample should be obtained and analysed. The liquid phase comprises most of the material in the container and is more representative of the overall composition of the SF6 in the container. When a discrepancy exists between vapor and liquid phase analyses, the liquid phase analysis shall govern, unless otherwise agreed to by purchaser-seller agreement.
5. Precautions
5.1 Refer to the section titled Interferences in Test Method D2029.
