Pressure specific gravity effect

When tank operators change a stored hquid, care must be exercised. If there is a significant increase in the specific gravity of the new hquid, the effective hydrostatic pressure acting on the tank walls is greater if the design hquid level is not reduced. 

Physical characteristics Molecular weight Vapour density Specific gravity Melting point Boiling point Solubility/miscibility with water Viscosity Particle size size distribution Eoaming/emulsification characteristics Critical temperature/pressure Expansion coefficient Surface tension Joule-Thompson effect Caking properties... 

The following analysis enables one to calculate the diameter of a pipeline transporting any compressible fluid. The required inputs are volumetric flow rate, the specific gravity of the gas relative to air, flow conditions, compressibility factor Z where Z is defined by nZRT = PV, the pressure at the point of origin and the destination, the pipe length, and pipe constants such as effective roughness. The working equations have been obtained from the literature. Since the friction factor... 

So far, we have explained the effects of atmospheric pressure on liquids and how external forces are distributed through liquids. Let us now focus our attention on forces generated by the weight of liquids themselves. To do this, we must first discuss density, specific gravity and Pascal s law. 

Aluminium hydroxide has a Moh hardness of about 3 and a specific gravity of 2.4. It decomposes endothermically with the release of water at about 200 °C and this makes it a very useful flame retardant filler, this being the principal reason for its use in polymers. The decomposition temperature is in fact too low for many thermoplastics applications, but it is widely used in low smoke P VC applications and finds some use in polyolefins. For these applications low aspect ratio particles with a size of about 1 micron and a specific surface area of 4-10 m g are preferred. The decomposition pathway can be diverted through the mono-hydrate by the application of pressure, and this may reduce the flame retardant effect [97]. This effect can be observed with the larger sized particles. Although it is chemically the hydroxide, it has for many years been known as alumina trihydrate and by the acronym ATH. 

In spite of its high specific gravity the apparent density of the needle-shaped crystals, according to Clark [15], is only 0.27 under a pressure of 240kg/cm2 it is 0.86. The crystals may be obtained in the form of pellets whose apparent density is about 0.8. The effect of the conditions of preparation have been thoroughly examined by Smolenski and Plucinski [13], They found that at a diazotization temperature as recommended by Clark, i.e. 15°C, the product pours with difficulty. Conversely, diazotization at a higher temperature (25-45°C) results in formation of a product with a density of about 0.82. 

Product oils from SYNTHOIL runs carried out at 415° and 450° C and 2,000 and 4,000 psi H2 pressures were analyzed with respect to asphaltene and oil content, elementary compositions (C, E, S, N), ash and physical properties (specific gravity and viscosity). Asphaltenes exert a large effect on the viscosity of the product oil, the viscosity increasing exponentially with asphaltene content. Viscosity of product oil is not only dependent on the amount but also on the molecular weight of asphaltenes present. At 415° C, asphaltenes with a molecular weight of 670 are formed and at 450° C asphaltenes with a molecular weight of 460. 

Often the most prominent effect is the increase in specific gravity. It should be emphasized that maximum effects are observed on extended treatment times at high relative vapor pressures. 

Absolute Specific Gravity (Abs sp gr, sp gr, d j or S) can be defined as the ratio of true weight of a substance (wt corrected to air buoyancy) to true wt of water contained in the same volume at the same temperature. For gases, the term sp gr refers to dry air at the same pressure temp. In US industries, the term "specific gravity", without the prefix "absolure" may refer to wts not corrected to the effects of air buoyancy (apparent wts). The sp grs using the uncorrected wts are known in science as Apparent Specific Gravities and they do not differ more than 0.1% from the sbsolute values (See also Ref 2, p 411 Ref 13, p 876... 

To size control valves for liquids, use a similar procedure and the relation C = V (G/Ap), where V is flow rate through the valve, in gal/min, Ap is pressure drop across the valve at maximum flow rate, in lb/in2, and G is specific gravity of the liquid. When a liquid has a specific gravity of 100 SSU or less, the effect of viscosity on the control action is negligible. 

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