Thermal expansion liquids

Lines or equipment which can be left full of liquid under non-flow conditions and which can be heated while completely blocked-in must have some means of relieving pressure built up by thermal expansion of the contained liquid. Solar radiation, as well as other heat sources, must be considered. Lines or equipment which are hotter than ambient when blocked in and which cannot otherwise be heated above the blocked-in temperature do not need protection against liquid thermal expansion. The following are common examples of some thermal expansion mechanisms. 

Piping - Sections of piping in any liquid service, whether onsite or offsite, which can be blocked in while liquid filled and subjected to liquid thermal expansion from subsequent heating, must be protected by either. 

For a liquid thermal expansion relief device that protects only a blocked-in portion of a piping system, the set pressure shall not exceed the lesser of the system test pressure or 120% of design pressure. 

If it is calculated that the volume of the gas space in the test cell will decrease significantly during the test, due to liquid thermal expansion, then account needs to be taken of this. Either the test can be performed at a lower fill level (at the cost of increased thermal inertia) or some estimate of the relationship between gas space volume and temperature should be made and the following equation used to find the pad gas pressure at any temperature ... 

The original reference also includes correlations for liquid and vapor specific volume, liquid thermal expansion coefficient, liquid and vapor enthalpy, liquid specific heat, and liquid and vapor Prandtl numbers. 

In LMFBR, thermal buckling could be induced by the large thermal gradients which appear at the free level of sodium. These thermal gradients can be fixed spatially by constructive devices or moving under the liquid thermal expansion. 

Fahrenheit scale displaced downwards so that Absolute Zero (-492°F) is 0° Rankine 32°F = 492° Rankine etc. Rankinite. 3Ca0.2Si02 melts incongruently at 1464°C to form dicalcium silicate and a liquid thermal expansion (20-1000°C) 13 x 10- . It is not found in portland cement. 

Size safety relief devices according to the appropriate safety code (see Table 3-4) for the most demanding of these possible upset conditions —closed valves on line or eqviipment —hydraulic expansion of liquid —thermal expansion... 

Equation (9.17). The slope of the curve below about 130 °C gives the thermal expansion coefficient for crystalline polyethylene, which is a hard plastic material. The volume expands sharply at the melting temperature. Above about 140 °C, the slope gives the thermal expansion coefficient of the plastic liquid. Thermal expansion coefficients are usually positive because increasing temperature causes a loosening up of the intermolecular bonds in the material. 

Several other physical properties besides mechanical properties also exhibit optimal behavior near = 2.4. These properties range from density and thermal expansion to glass-forming ability [11, 16, 44]. For example. Fig. 2.2 shows the density and liquid thermal expansion versus for the binary Ge-Se and ternary Ge-Sb-Se systems. Both properties show clear extrema near = 2.4. 

Thermal expansion coefficient of the film Thermal expansion coefficient of the liquid Thermal expansion coefficient of the solid Thermal expansion coefficient of the substrate Phase shift... 

If the liquid content of the vessel is above the critical point, a minimum latent heat of 116 kJ/kg is to be used to estimate the fire contingency. Liquid thermal expansion can also be used to eshmate the contingency if reliable data are available. Normally, physical properties estimated through simulation packages are not very reliable when the liquid is above the critical point. 

The oil density at surface is readily measured by placing a sample in a cylindrical flask and using a graduated hydrometer. The API gravity of a crude sample will be affected by temperature because the thermal expansion of hydrocarbon liquids is significant, especially for more volatile oils. It is therefore important to record the temperature at... 

Below Tg the material is hard and rigid with a coefficient of thermal expansion equal to roughly half that of the liquid. With respect to mechanical properties, the glass is closer in behavior to a crystalline solid than to a... 

Coefficient of Linear Thermal Expansion. The coefficients of linear thermal expansion of polymers are higher than those for most rigid materials at ambient temperatures because of the supercooled-liquid nature of the polymeric state, and this applies to the cellular state as well. Variation of this property with density and temperature has been reported for polystyrene foams (202) and for foams in general (22). When cellular polymers are used as components of large stmctures, the coefficient of thermal expansion must be considered carefully because of its magnitude compared with those of most nonpolymeric stmctural materials (203). 

From Mercury—Density and Thermal Expansion at Atmospheric Pressure and Temperatures from 0 to. 350 C, Tables of Standard Handbook Data, Standartov, Moscow, 1978. The density values obtainable from those cited for the specific volume of the saturated liquid in the Thermodynamic Properties subsection show minor differences. No attempt was made to adjust either set. 

No tables of the coefficients of thermal expansion of gases are given in this edition. The coefficient at constant pressure, l/t)(3 0/3T)p for an ideal gas is merely the reciprocal of the absolute temperature. For a real gas or liquid, both it and the coefficient at constant volume, 1/p (3p/3T),, should be calculated either from the equation of state or from tabulated PVT data. 

Thermal-expansion and -contraction loads occur when a piping system is prevented from free thermal expansion or contraction as a result of anchors and restraints or undergoes large, rapid temperature changes or unequal temperature distribution because of an injection of cold liquid striking the wall of a pipe cariying hot gas. 

Thermal expan sion. Equipment and pipehues which are liquid-full under normal operating conditions are subject to hydrauhc expansion if the temperature increases. Common sources of heat that can result in high pressures due to thermal expansion include solar radiation, steam or other heated tracing, heating coils, and heat transfer from other pieces of equipment. 

The viscosity of liquid silicates such as drose containing barium oxide and silica show a rapid fall between pure silica and 20 mole per cent of metal oxide of nearly an order of magnitude at 2000 K, followed by a slower decrease as more metal oxide is added. The viscosity then decreases by a factor of two between 20 and 40 mole per cent. The activation energy for viscous flow decreases from 560 kJ in pure silica to 160-180kJmol as the network is broken up by metal oxide addition. The introduction of CaFa into a silicate melt reduces the viscosity markedly, typically by about a factor of drree. There is a rapid increase in the thermal expansivity coefficient as the network is dispersed, from practically zero in solid silica to around 40 cm moP in a typical soda-lime glass. 

Full liquid containers require protection from thermal expansion. Such relief valves are generally quite small. Two examples are... 

Cathodoluminescence microscopy and spectroscopy techniques are powerful tools for analyzing the spatial uniformity of stresses in mismatched heterostructures, such as GaAs/Si and GaAs/InP. The stresses in such systems are due to the difference in thermal expansion coefficients between the epitaxial layer and the substrate. The presence of stress in the epitaxial layer leads to the modification of the band structure, and thus affects its electronic properties it also can cause the migration of dislocations, which may lead to the degradation of optoelectronic devices based on such mismatched heterostructures. This application employs low-temperature (preferably liquid-helium) CL microscopy and spectroscopy in conjunction with the known behavior of the optical transitions in the presence of stress to analyze the spatial uniformity of stress in GaAs epitaxial layers. This analysis can reveal,... 

On heating up, thermal expansion of a liquid in sealed piping, equipment or a container may exert sufficient hydraulic pressure to cause rupture or failure. (Hence specific filling ratios are followed with containers, e.g. road tankers.)... 

Table 4.15 Pressure increase of common liquids due to thermal expansion on 16.6°C temperature rise ...

Liquids can also exert pressure due to thermal expansion. Table 4.15 provides an indication of pressure increases due to temperature increases for selected common liquids in full containers or pipes. Serious accidents can arise unless the design of rigid plant items such as pipework takes into account the changes in volume of liquids with temperature fluctuation by the following or combinations thereof ... 

Consideration should be given to the effects of thermal expansion of liquids and pressure-relief valves installed unless ... 

Glass transition Transition region or state in which an amorphous polymer changed from (or to) a viscous or rubbery condition to (or from) a hard and relatively brittle one. Transition occurs over a narrow temperature region similar to solidification of a liquid to a glassy state. This transformation causes hardness, brittleness, thermal expansibility, specific heat, and other properties to change dramatically. 

PR valves handling materials which are liquid or partially liquid at the valve inlet. An exception to this is made for certain thermal expansion relief valves as described below. 

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