Specific gravity ratio

Specific gravity ratio of weight per unit volume of a substance to the weight of the same unit volume of water. 

Class by uses Apparent specific gravity Ratio of void (%) Weight of unit vol. Moisture content (kg/m3) (% in weight) ... 

Specific gravity - Ratio of the mass density of a material to that of water. Since one must specify the temperature of both the sample and the water to have a precisely defined quantity, the use of this term is now discouraged. 

Plastic type Specific gravity (ratio of the mass of a material to the mass of an equal volume of water at 4°C)... 

Figure 7.21 Modulus vs. specific gravity ratio for different materials follows a straight line...

Relative density Originally called Specific Gravity, ratio of mass of given volume of substance to mass of equal volume of water at 4°C. 

A generation of new aluminum-lithium alloys have been developed recently for use by the aircraft and aerospace industries. These materials have relatively low densities (between about 2.5 and 2.6 g/cm ), high specific moduli (elastic modulus-specific gravity ratios), and excellent fatigue and low-temperature toughness properties. Furthermore, some of them may be precipitation hardened. However, these materials are more costly to manufacture than the conventional aluminum alloys because special processing techniques are required as a result of lithium s chemical reactivity. 

The specific gravity of a pure hydrocarbon is linked to its H/C ratio, the specific gravity decreasing as the H/C ratio increases. Table 3.2 illustrates this variation for hydrocarbons having 14 carbon atoms. 

It is based on the observations that the specific gravities of hydrocarbons are related to their H/C ratios (and thus to their chemical character) and that their boiling points are linked to the number of carbon atoms in their molecules. 

Specific gravity compared with H/C ratio for pure hydrocarbons. 

The standard specific gravity is the ratio of the density of a hydrocarbon at 15.55°C (60°F) to that of water at the same temperature. It differs from the specific gravity d] which is the ratio of the density of a hydrocarbon at 15°C to that of water at 4°C. 

QuaHty control in the production of organic solvent finish removers may be done by gas—Hquid chromatography, which allows the manufacturer to determine the actual ratio of volatile solvent present in the finished product. If the product does not meet specifications, solvents can be added to bring the product to an acceptable composition. A less expensive approach is to use a hydrometer to determine the specific gravity of the product. The specific gravity indicates if the proper blend has been reached. Nonaqueous acid—base titration may be used to determine the amount of acid or alkaline activator present in a remover. 

Specific gravity (sp gr) is a measure of the relative weight of one Hquid compared to a universaHy familiar Hquid, generaHy water. More speciftcaHy, sp gr is a ratio of the density of a Hquid divided by the density of Hquid water at 16°C (60°F). Specific gravities of selected Hquids are shown in Table 1. 

Dimensionless Quantities. Certain quantities, eg, refractive index and relative density (formerly specific gravity), are expressed by pure numbers. In these cases, the corresponding SI unit is the ratio of the same two SI units, which cancel each other, leaving a dimensionless unit. The SI unit of dimensionless quantities may be expressed as 1. Units for dimensionless quantities such as percent and parts per million (ppm) may also be used with SI in the latter case, it is important to indicate whether the parts per million are by volume or by mass. 

Density and Relative Density. Density is mass per unit volume and in SI is normally expressed as kilograms per cubic meter (density of water = 1000 kg/m or 1 g/cm ). The term specific gravity was formerly the accepted dimensionless value describing the ratio of the density of sohds and Hquids to the density of water at 4°C or for gases to the density of ak at standard conditions. The term specific gravity is being replaced by relative mass density, a more descriptive term. 

Density is defined as the mass of a substance contained in a unit volume. In the SI system of units, the ratio of the density of a substance to the density of water at I5°C is known as its relative density, while the older term specific gravity is the ratio relative to water at 60°F. Various units of density, such as kg/m, Ib-mass/fF, and g/cm, are commonly used. In addition, molar densities, or the density divided by the molecular weight, is often specified. This section briefly discusses methods of correlation of density as a function of temperature and presents the most common accurate methods for prediction of vapor, liquid, and solid density. 

Density and Specific Gravity For binary or pseudobinary mixtures of hquids or gases or a solution of a solid or gas in a solvent, the density is a funcrion of the composition at a given temperature and pressure. Specific gravity is the ratio of the density of a noncompress-ible substance to the density of water at the same physical conditions. For nonideal solutions, empirical calibration will give the relationship between density and composition. Several types of measuring devices are described below. 

The sharpness of separation of the mineral from the gangue is dependent on (1) the stability of the suspension, which is influenced by the size of the medium (2) the specific gravity of the medium (3) the cleanliness of the medium (4) the cone angle (5) the size and ratios of the internal openings in the cyclone (inlet, apex, and vortex) and (6) the pressure at which the pulp is introduced into the cyclone. A 20° cone angle is the most common. Cyclone diameter will be determined by the separation to be made as well as by the capacity required. The 0.5- and 0.6-m (20- and 24-in) cyclones are most common in coal plants, whereas multiple cones of 0.25- or 0.3-m (10- or 12-in) diameter are used in higher-gravity separations. 

The specific gravity, SG, is the ratio of the density of a given gas to the density of dry air at the same temperature and pressure. It can be calculated from the ratio of molecular weights if the given gas is a perfect gas. 

To assist the engineer in making estimates, the curve in Figure 3-6 gives values of efficiency plotted against pressure ratios. The values on the curve include a 95% mechanical efficiency and a valve velocity of 3,000 feet per minute. Table 3-1 and Table 3-2 are included to permit a correction to be made to the compressor horsepower for specific gravity and low inlet pressure. They are included to help illustrate the influence of these factors to the power required. The application of these factors to... 

Specific Gravity (SG) — the ratio of the density of a liquid as compared with that of water. Insoluble materials will sink or float in water depending on the SG. Materials heavier than water have SGs >1, and materials lighter than water have SGs <1. Thus, lead, mercury, and carbon tetrachloride with SGs of 11.3, 13.6, and 1.6, respectively, will sink, whereas gasoline with a SG of 0.66 to 0.69, will... 

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