ASTM D4052 for density, relative density and API gravity of liquids
ASTM D4052 standard test method for density, relative density, and API gravity of liquids by digital density meter
8. Sampling, Test Specimens, and Test Units
8.1 Sampling is defined as all the steps required to obtain an aliquot of the contents of any pipe, tank, or other system, and to place the sample into the laboratory test container. The laboratory test container and sample volume shall be of sufficient capacity to mix the sample and obtain a homogeneous sample for analysis.
8.2 Laboratory Sample - Use only representative samples obtained as specified in Practices D4057 or D4177 for this test method.
8.3 Test Specimen - A portion or volume of sample obtained from the laboratory sample and delivered to the density analyzer sample tube. The test specimen is obtained as follows:
8.3.1 Mix the sample if required to homogenize taking care to avoid the introduction of air bubbles. The mixing may be accomplished as described in Practice D4177 or Test Method D4377. Mixing at room temperature in an open container can result in the loss of volatile material from certain sample types (e.g., gasoline samples), so mixing in closed, pressurized containers or at sub-ambient temperatures is required for such sample types where loss of volatile material is a potential concern. For some sample types, such as viscous lube oils that are prone to having entrained air or gas bubbles present in the sample, the use of an ultrasonic bath (see 6.7) without the heater turned on (if so equipped), has been found effective in dissipating bubbles typically within 10 minutes.
8.3.2 For manual injections, draw the test specimen from a properly mixed laboratory sample using an appropriate syringe. If the proper density analyzer attachments and connecting tubes are used, as described in 6.4, then the test specimen can be delivered directly to the analyzer's sample tube from the mixing container. For automated injections, it is necessary to first transfer a portion of sample by appropriate means from a properly mixed laboratory sample to the autosampler, and take the necessary steps to ensure the integrity of the test specimen prior to and during the analysis. Follow the manufacturer's instructions.
