Specific gravity test

The data from the density (specific gravity) test method (ASTM D1298 IP 160) provides a means of identification of a grade of naphtha but is not a guarantee of composition and can only be used to indicate evaluate product composition or quality when used in conjunction with the data from other test methods. Density data are used primarily to convert naphtha volume to a weight basis, a requirement in many of the industries concerned. For the necessary temperature corrections and also for volume corrections, the appropriate sections of the petroleum measurement tables (ASTM D1250 IP 200) are used. 

A routine method for determining relative crystallinity based on the amorphous bands in the spectrum has proved more rapid and precise than the x-ray method. In practice, the ratio of the 778 cm-1 (12.85 ft) and 2367 cm-1 (4.22 ft) band intensities is measured. Use of a ratio eliminates the thickness measurement and increases precision to about 1% at 50% crystallinity and considerably better at higher levels. A density measurement and an infrared crystallinity determination when combined give an estimate of the fraction of microvoids which can occur in molded specimens of polytetrafluoroethylene. The density of a sample is predicted on the basis of its crystallinity as measured by the infrared method and the difference between this density and the actual density measured by displacement in water is a measure of the microvoid content. This determination is precise to about 0,2% voids by volume. By the use of confirmatory infrared measurements, it is possible to check the possibility that the presence of a substantial percentage of voids may have led to erroneous indications of the molecular weight in the standard specific gravity test discussed earlier. 

Substituted blind specimens must be certified for creatinine concentration and specific gravity to satisfy the criteria for a substituted specimen using confirmatory creatinine and specific gravity tests. 

I Substituted Specimen —A primary specimen is considered substituted if the creatinine concentration is less than 2 mg/dL and the specific gravity is less than or equal to 1.0010 or greater than or equal to 1.0200 on both the initial and confirmatory creatinine tests and on both the initial and confirmatory specific gravity tests on two separate aliquots. 

Analytical tests are important to material suppliers and processors. These tests provide basic information that is necessary for characterizing and qualifying the material. Analytical tests such as density and specific gravity tests are used as a... 

Figure 10-1. Specific gravity test. (Courtesy of Ohaus Scale Corporation.) b) Electronic version of the apparatus to measure density and specific gravity. (Courtesy Qualitest USA.)...

The increasing used of plasticizers, fillers, reinforcing agents, and other additives makes the identification of plastics by the specific gravity test very difficult. The test is described in detail in Chapter 10. 

There are many types of nylons with a specific gravity ranging from 1.04 to 1.17. All types burn with blue flames and yellow tips and give off a burnt wool or hair odor. Nylon self-extinguishes on removal of the flame. Phenol, m-cresol, and formic acid are the most common solvents. Different types of nylons can be identified by the Fisher-Johns melting-point test (ASTM D 789). Solubility and specific gravity tests are also used to differentiate between the types of nylons. However, infrared spectroscopy is the best method for positive identification. 

Tests for Bituminous and Semisolid Materials. The most common tests for asphaltic substances are the ductility, penetration, ring-and-ball softening points (E28), and specific-gravity tests. The ductility (D113) of an asphalt is a measure of its capacity to elongate or stretch and is an indication of the ability of the material to flow and thereby mend a rupture in the surface of the material. A briquette of the asphalt... 

The specific gravity testing showed very good agreement between the reference and failed samples. The reference part material produced an average specific gravity of 0.954, with the failed part material yielding a value of 0.953. These results matched the density indicated on the Alathon M 5370 Data Sheet, 0.953 g/ml. The determined specific... 

Testing. Chemical analyses are done on all manufactured abrasives, as well as physical tests such as sieve analyses, specific gravity, impact strength, and loose poured density (a rough measure of particle shape). Special abrasives such as sintered sol—gel aluminas require more sophisticated tests such as electron microscope measurement of a-alumina crystal si2e, and indentation microhardness. 

The American Society for Testing and Materials (ASTM) and the American Oil Chemists Society (AOCS) provide standard methods for determining properties that are important in characterization of dimer acids. Characterization of dimer acids for acid and saponification values, unsaponiftables, and specific gravity are done by AOCS standard methods ... 

Material No. of tests Specific gravity Work index Material No. of tests Specific gravity Work index ... 

Quality control tests on the resins most commonly employed are for specific gravity, viscosity, colour, clarity and gel time under standard conditions,... 

Spec. Sheet Specification Sheet. Detailed information of a product including, tests, color, odor, specific gravity, bacterial strains, other major ingredients, etc. 

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