ASTM D6749 for pour point of petroleum products (Automatic air pressure method)
6. Apparatus
6.1 Automatic Apparatus - The automatic pour point apparatus described in this test method is a microprocessor controlled apparatus that is capable of heating and cooling a specimen, applying air pressure onto the specimen's surface, detecting the specimen's surface movement, and then computing and reporting the pour point (see Fig. 1). The detail is described in Annex A1.
6.2 Test Jar, clear cylindrical glass with a flat bottom with an approximate capacity of 12 mL. Approximately 4.5 mL of sample specimen is contained when filled to the scribed line. The test jar is fitted with a test jar cap assembly on its top to form an air chamber over the test specimen.
6.3 Test Jar Cap Assembly - A plastic cap is installed on top of the test jar with the provision of sealing air. A glass tube with a metallic tip shall be inserted from underneath the plastic cap into the round hole in the center of the test jar cap. The top end of the round hole is connected to an air pressure sensor by way of a vinyl tube. To supply air pressure to the specimen's surface, a vinyl tube connected to an air syringe is located adjacent to the glass tube through an orifice in the plastic cap. When a specimen is to be tested, the test jar cap assembly is installed on the test jar with the lower end of the glass tube inserted into the specimen in the test jar. The glass tube and the test jar form a communicating tube. A temperature sensor in a small diameter metallic sheath shall be installed in the center of the glass tube.
6.4 Metallic Block Bath, a metallic block with a cylindrical hole to fit the test jar. The metallic block assembly shall have a provision for cooling/heating. A temperature sensor is embedded in the metallic block to monitor its temperature.
7. Reagents and Materials
7.1 Cleaning Agents, capable of cleaning and drying the test jar, temperature sensor, and glass tube after each test. Chemical agents such as alcohol, petroleum-based solvents, and acetone have been found suitable to use. (Warning - Flammable.) (Warning - May be harmful by itself or when evaporated.)
