Absolute density

For practical engineering purposes, relative density at 15°C (288 K), widely used in countries outside the United States, is considered equivalent to specific gravity at 60°F (288.6 K). With the adoption of SI units, the American Petroleum Institute favors absolute density at 288 K instead of degrees API. 

Absolute Density Bulk Density Size Distribution Friability... 

Table 10 Capacities, Average Swelling Percentages, and Absolute Densities for Sulfonated Corncob Cationic Resins...

Paraformaldehyde content (% wt/wt) Capacity (mEq g ) Weight swelling (%) Absolute density (gm" ) ... 

The connection between the multiplicative insensitivity of 12 and thermodynamics is actually rather intuitive classically, we are normally only concerned with entropy differences, not absolute entropy values. Along these lines, if we examine Boltzmann s equation, S = kB In 12, where kB is the Boltzmann constant, we see that a multiplicative uncertainty in the density of states translates to an additive uncertainty in the entropy. From a simulation perspective, this implies that we need not converge to an absolute density of states. Typically, however, one implements a heuristic rule which defines the minimum value of the working density of states to be one. 

The volumetric systems of Bradshaw and Schleicher (106) and Kell and Whalley (26,32) are the most precise methods of directly measuring the absolute densities or volumes at high pressures. These methods, however, are not ideally suitable for making systematic density studies of aqueous electrolyte solutions as a function of P and T because of the arduous nature of the experimental work and the loss of precision in very dilute solutions. 

SI units, the American Petroleum Institute favors absolute density at 288 K instead of degrees API. 

Other Measurements. Particle size distributions were measured by the Coulter Counter method. Absolute density measurements were made using the well known pycnometer method. 

Absolute Densities, Relative X-Ray Absorptions and Radiologic Image Signal to Noise Ratios of Several X-Ray Phosphors... 

The desireable characteristics are high absolute densities and atomic numbers from about 55-65 to reduce quantum noise. 

A porous particle contains many interior voids known as open or closed pores. A pore is characterized as open when it is connected to the exterior surface of the particle, whereas a pore is closed (or blind) when it is inaccessible from the surface. So, a fluid flowing around a particle can see an open pore, but not a closed one. There are several densities used in the literature and therefore one has to know which density is being referred to (Table 3.15). True density may be defined as the mass of a powder or particle divided by its volume excluding all pores and voids. True density is also referred to as absolute density or crystalline density in the case of pure compounds. However, this density is very difficult to be determined and can be calculated only through X-ray or neutron diffraction analysis of single-crystal samples. Particle density is defined as the mass of a particle divided by its hydrodynamic volume. The hydrodynamic volume includes the volume of all the open and closed pores. Practically, the hydrodynamic volume is identified with the volume included by the outer surface of the particle. The particle density is also called apparent or envelope density. The term skeletal density is also used. The skeletal density of a porous particle is higher than the particle one, since it is the mass of the particle divided by the volume of solid material making up the particle. In this volume, the closed pores volume is included. The interrelationship between these two types of density is as follows (ASTM, 1994 BSI, 1991) ... 

Some important aspects of foam are not included in this list. We mentioned void volume earlier. This parameter is related to density by a comparison of bulk density to absolute density. We will discuss each of these measures of foam quality and relate their applicability to the theme of this book. Later in the chapter we will show how formulation and processing techniques are used to adjust and control the most important parameters. 

The void volume can be determined by displacement in water. This is problematic when investigating a hydrophilic polymer or when accurate measurements are required. A good estimate of void volume can be obtained by comparing the absolute density of the polymer with the bulk density determined via ASTM D3574-95. For instance, let us assume that isocyanate and the polyol have specific gravities of 1.0. If a polyurethane is made of this combination, the absolute density of the polymer... 

While there is no direct data to support this statement, we have found vastly different shelf-lives for products which contain essentially similiar trace metal levels, surface oils, and absolute densities. We can find no other explanation for the differences in shelf-life other than matrix porosity. This area needs to be further studied in order to confirm this hypothesis and then take advantage of it to improve the shelf-life of spray dried flavorings. 

Specific Gravity, also called absolute density, is the relation betw wt and volume of grains disregarding che air spaces. The Bofors manual(Ref 10,p 22) describes two methods Mohr-Wesrphal s balance and pycnometer methods. In the BurMines method(Ref 2,p 67), an apparatus called densimeter is used. In US Spec JAN-P-223A(Ref 11) two methods are described in which either a 25-ml bottle with a 10-g sample or a large... 

In most cases of loading ammunition, the higher the absolute density of an explosive, the higher is its loading density (See also Limiting Density and Maximum Loading Density)... 

It increases with the increase of "densite reelle (see Absolute Density, item A) and varies with the size and form of the grains. It is the "Densite gravimetrique which governs the conditions of loading the ammunition, especially for... 

Refs (Density Specific Gravity) 1) W.O. Snelling C.G. Storm, "The Analysis of Black Powder and Dynamite , USBurMines Bull 51, W ashington, DC (1916), 67-8 [Determination of gravimetric and absolute densities (Snelling s d ensimeter) plate II, gravimetric balance]... 

Clark reports that pentryl has an Absolute density of 1.82 and an apparent density of only 0.45. When compressed in a detonator shell at a pressure of 3400 pounds Wr square inch, it has an apparent density of 0.74. It is soluble to some extent in most of the common organic solvents, and is very readily soluble in nitroglycerin. In the drop test with a 2-kilogram weight, 0.02 gram of pentryl was exploded by a drop of 30 cm., a similar sample of... 

Metallic zinc is characterized by a brilliant white luster which tarnishes readily to produce the familiar dull gray appearance. Between 100 and 150°C, the metal is both malleable and ductile. Pure zinc melts at 419.3°C and boils at 907°C. The absolute density of cast zinc is 6.94, while that of rolled zinc is 7.14. 

For non-porous solids the particle density is equal to the true, skeletal, or absolute density, Pabs which can be measured using either a specific gravity bottle or air pycnometer ... 

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