ASTM D1298 for density of crude petroleum and liquid petroleum products
ASTM D1298 for density of crude petroleum and liquid petroleum products by hydrometer method
6. Apparatus
6.1 Hydrometers, of glass, graduated in units of density, relative density, or API gravity as required, conforming to Specification E 100 or ISO 649-1, and the requirements given in Table 1.

6.1.1 The user should ascertain that the instruments used for this test conform to the requirements set out above with respect to materials, dimensions, and scale errors. In cases where the instrument is provided with a calibration certificate issued by a recognized standardizing body, the instrument is classed as certified and the appropriate corrections listed shall be applied to the observed readings. Instruments that satisfy the requirements of this test method, but are not provided with a recognized calibration certificate, are classed as uncertified.

6.2 Thermometers, having range, graduation intervals and maximum permitted scale error shown in Table 2 and conforming to Specification E 1 or IP Appendix A.

6.2.1 Alternate measuring devices or systems may be used, provided that the total uncertainty of the calibrated system is no greater than when using liquid-in-glass thermometers.

6.3 Hydrometer Cylinder, clear glass, plastic (see 6.3.1), or metal. The inside diameter of the cylinder shall be at least 25mm greater than the outside diameter of the hydrometer and the height shall be such that the appropriate hydrometer floats in the test portion with at least 25 mm clearance between the bottom of the hydrometer and the bottom of the cylinder.

6.3.1 Hydrometer cylinders constructed of plastic materials shall be resistant to discoloration or attack by oil samples and shall not affect the material being tested. They shall not become opaque under prolonged exposure to sunlight.

6.4 Constant-Temperature Bath, if required, of dimensions such that it can accommodate the hydrometer cylinder with the test portion fully immersed below the test portion liquid surface, and a temperature control system capable of maintaining the bath temperature within 0.25°C of the test temperature throughout the duration of the test.

6.5 Stirring Rod, optional, of glass or plastic, approximately 400 mm in length.