Temperature specification

The maximum concentration atltainable under such conditions is termed the solubility of the substance at the specific temperature used in the experiment, since solubility generally increases with rising temperature. Solubility is usually expressed in grams per 100 g of solvent, or grams per 100 g of solution. Sometimes, for practical convenience, it may be expressed in grams per 100 ml of solvent or solution. 

A saturated aqueous solution in contact with an excess of a definite solid phase at a given temperature will maintain constant humidity in an enclosed space. Table 11.4 gives a number of salts suitable for this purpose. The aqueous tension (vapor pressure, in millimeters of Hg) of a solution at a given temperature is found by multiplying the decimal fraction of the humidity by the aqueous tension at 100 percent humidity for the specific temperature. For example, the aqueous tension of a saturated solution of NaCl at 20°C is 0.757 X 17.54 = 13.28 mmHg and at 80°C it is 0.764 X 355.1 = 271.3 mmHg. 

Melt Index or Melt Viscosity. Melt index describes the flow behavior of a polymer at a specific temperature under specific pressure. If the melt index is low, its melt viscosity or melt flow resistance is high the latter is a term that denotes the resistance of molten polymer to flow when making film, pipe, or containers. ASTM D1238 is the designated method for this test. 

Another measure of refractoriaess is the hot-compressive strength or hot-load test for refractory bricks or formed specialties. The specimen carries a static load from 69 kPa (10 psi) to 172 kPa (25 psi). It is heated at a specific rate to a specific temperature which is then held for 1.5 h, or it is heated at a specific rate until it fads. The percent deformation or the temperature of fadure is measured. The procedure is described ia ASTM C16. 

Some indicators can determine whether a specific temperature has been achieved. Because the entrapment of large amounts of air can result in the lowering of steam temperatures, these indicators react to some critical defect in sterilization conditions. Eor each different temperature, a different indicator must be used. 

Thermal Properties. The thermal stabiUty of cellulose esters is deterrnined by heating a known amount of ester in a test tube at a specific temperature a specified length of time, after which the sample is dissolved in a given amount of solvent and its intrinsic viscosity and solution color are deterrnined. Solution color is deterrnined spectroscopically and is compared to platinum—cobalt standards. Differential thermal analysis (dta) has also been reported as a method for determining the relative heat stabiUty of cellulose esters (127). 

The fraction of the total conductivity at a specific temperature and composition owing to the conduction of specie i is called the transference number... 

Meat Products. Citric acid is used in cured meat products to increase the effectiveness of the antioxidant preservatives, as a processing aid, and a texture modifier. It is often encapsulated and released at a specific temperature from a controlled release matrix. 

The simulation models of the flow-sheeting system must make frequent requests for properties at specific temperatures, pressures, and compositions. Computer-program calls for such data are usually made in a rigorously defined manner, which is independent of both the point data generation models and the particular components. These point generation routines provide the property values, using selected methods that base their calculations on a set of parameters for each component. 

Free moisture content is the Hquid content that is removable at a specific temperature and humidity. Eree moisture may include bound and unbound moisture, and is equal to the total average moisture content minus the equiHbrium moisture content for the specific drying conditions. 

The wet bulb or saturation temperature curve indicates the maximum weight of vapor that can be carried by a unit weight of dry gas. For any temperature on the abscissa, saturation humidity is found by reading up to the saturation temperature curve, then across to the ordinate, kg/kg dry air. At saturation, the partial pressure of vapor in the gas is the vapor pressure of the hquid at the specific temperature ... 

Since NO production depends on the flame temperature and quantity of excess air, achieving required limits may not be possible through burner design alone. Therefore, many new designs incorporate DENOX units that employ catalytic methods to reduce the NO limit. Platinum-containing monolithic catalysts are used (36). Each catalyst performs optimally for a specific temperature range, and most of them work properly around 400°C. 

The vapor pressure of a liquid is the absolute pressure at which the liquid vaporizes or converts into a gas at a specific temperature. Normally, the units are expressed in pounds per square inch absolute (psia). The vapor pressure of a liquid increases with its temperature. For this reason the temperature should be specified for a declared vapor pressure. 

Tlie vapour pressure of a chemical provides an indication of its volatility at any specific temperature. As an approximation, the vapour pressure p of a pure chemical is given by... 

Temperature The degree of molecular activity in a body high activity gives a high temperature, low activity a low temperature. The degree of activity is based on the assumption that absolute zero has no molecular movement at all. The following are some specific temperatures ... 

But another approach to multi-step cooling [8, 9] involves dealing with the turbine expansion in a manner similar to that of analysing a polytropic expansion. Fig. 4.4 shows gas flow (1 + ijj) at (p,T) entering an elementary process made up of a mixing process at constant pressure p, in which the specific temperature drops from temperature T to temperature T, followed by an isentropic expansion in which the pressure changes to (p dp) and the temperature changes from T to (7 - - dT). 

A single rupture disk can be used as the only overpressure protection on a vessel or system (Figure 7-10). The disk must be stamped by the manufacturer with the guaranteed bursting pressure at a specific temperature. The disk must rupture within +5% of its stampied bursting pressure at its specified burst temperature of operation. The expected burst temperature may need to be determined by calculation or extrapolation to be consistent with the selected pressure. 

Systems of two or more hydrocarbon, chemical and water components may be non-ideal for a variety of reasons. In order to accurately predict the distillation performance of these systems, accurate, experimental data are necessary. Second best is the use of specific empirical relationships that predict tvith varying degrees of accuracy the vapor pressure-concentration relationships at specific temperatures and pressures. 

Activity coefficients are equal to 1.0 for an ideal solution when the mole fraction is equal to the activity. The activity (a) of a component, i, at a specific temperature, pressure and composition is defined as the ratio of the fugacity of i at these conditions to the fugacity of i at the standard state [54]. 

Vt = V + Vs mols of vapor at a specific temperature and pressure, leaving flash zone per unit time Vs = mols of non-condensable gases entering with the feed, F, and leaving with the vapor, V, per unit time... 

L = mols of liquid at a specific temperature and pressure, from F, per unit time i = specific individual component in mixture Kj = equilibrium K values for a specific component at a specific temperature and pressure, from References 18, 65, 79, 99, 131, 235 T = temperature, abs... 

Relative volatility is the volatility separation factor in a vapor-liquid system, i.e., the volatility of one component divided by the volatility of the other. It is the tendency for one component in a liquid mixture to separate upon distillation from the other. The term is expressed as fhe ratio of vapor pressure of the more volatile to the less volatile in the liquid mixture, and therefore g is always equal to 1.0 or greater, g means the relationship of the more volatile or low boiler to the less volatile or high boiler at a constant specific temperature. The greater the value of a, the easier will be the desired separation. Relative volatility can be calculated between any two components in a mixture, binary or multicomponent. One of the substances is chosen as the reference to which the other component is compared. 

Density is defined as the mass of unit volume of a material at a specific temperature. A more useful unit used by the petroleum industry is... 

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