Expanded liquids

On compression, a gaseous phase may condense to a liquid-expanded, L phase via a first-order transition. This transition is difficult to study experimentally because of the small film pressures involved and the need to avoid any impurities [76,193]. There is ample evidence that the transition is clearly first-order there are discontinuities in v-a plots, a latent heat of vaporization associated with the transition and two coexisting phases can be seen. Also, fluctuations in the surface potential [194] in the two phase region indicate two-phase coexistence. The general situation is reminiscent of three-dimensional vapor-liquid condensation and can be treated by the two-dimensional van der Waals equation (Eq. Ill-104) [195] or statistical mechanical models [191]. 

L. The liquid-expanded, L phase is a two-dimensionally isotropic arrangement of amphiphiles. This is in the smectic A class of liquidlike in-plane structure. There is a continuing debate on how best to formulate an equation of state of the liquid-expanded monolayer. Such monolayers are fluid and coherent, yet the average intermolecular distance is much greater than for bulk liquids. A typical bulk liquid is perhaps 10% less dense than its corresponding solid state. 

Because of the charged nature of many Langmuir films, fairly marked effects of changing the pH of the substrate phase are often observed. An obvious case is that of the fatty-acid monolayers these will be ionized on alkaline substrates, and as a result of the repulsion between the charged polar groups, the film reverts to a gaseous or liquid expanded state at a much lower temperature than does the acid form [121]. Also, the surface potential drops since, as illustrated in Fig. XV-13, the presence of nearby counterions introduces a dipole opposite in orientation to that previously present. A similar situation is found with long-chain amines on acid substrates [122]. 

Gate valves are used to minimize pressure drop in the open position and to stop the flow of fluid rather than to regulate it. The problem, when the valve is closed, of pressure buildup in the bonnet from cold liquids expanding or chemical action between fluid and bonnet should be solved oy a relief valve or by notching the upstream seat ring. 

Frank T. Bodurtha/ Sc D / E. I. du Pont de Nemours and Co., Inc., (retired) Consultant, Frank T. Bodui tha, Inc. (Gas Explosions Unconfined Vapor Cloud Explosions [UVCE.s] and Boiling Liquid Expanding Vapor Explosions [BLEVE.s])... 

UNCONFINED VAPOR CLOUD EXPLOSIONS (UVCEs) AND BOILING LIQUID EXPANDING VAPOR EXPLOSIONS (BLEVEs)... 

BLEVE Boiling Liquid Expanding Vapor Explosion... 

A stream of 100 gpm (379 1/min) liquid expanding from 1,000 psi (6,900 kN/m ) to 100 psi (690 kN/m ) if it does not flash will develop approximately 40 hp (29.9 kW). Flashing usually more than doubles the power. Although this is only a small fraetion of the total required refrigeration, it is near the eoldest point in the system and is valuable. A hundred hp is the equivalent to a quarter of a million Btu per hour (73.3 kW) of heat. This would vaporize 2,900 lb (1,315 kg) per hour of liquid nitrogen at an absolute pressure of 20 psi (138 kN/m ). 

BLEVE, BOILING LIQUID EXPANDING VAPOUR EXPLOSION Instantaneous release and ignition of flammable vapour upon rupture of a vessel eontaining flammable liquid above its atmospherie boiling point. 

Explosion a confined vapour cloud explosion (CVCE) can result from ignition of vapour within a building or equipment a boiling liquid expanding vapour explosion (BLEVE) can result when unvented containers of flammable chemicals burst with explosive violence as a result of the build-up of internal pressure unconfmed vapour cloud explosion (UVCE) can result from ignition of a very large vapour or gas/air cloud. 

Boiling liquid expanding vapour explosion follows failure of a pressurized eontainer of flaimnable liquid, e.g. LPG, or a sealed vessel eontaining volatile flammable liquids, under fire eonditions. Ignition results in a fireball and missiles. 

Avoid direct sunshine on containment surfaces in hot climates. Direct spills of flammable materials away from pressurized storage vessels to reduce the risk of a boiling liquid expanding vapor explosion (BLEVE). 

Undesired reactions catalyzed by materials of construction or by ancillary materials such as pipe dope and lubricants Boiling liquid, expanding vapor explosions (BLEVEs)... 

At first it was thought that the spheres burst because their relief valves were too small. But later it was realized that the metal in the upper portions of tlie spheres was softened by the heat and lost its strength. Below the liquid level, the boiling liquid kept the metal cool. Incidents such as this one in which a vessel bursts because the metal gets too hot are known as Boiling Liquid Expanding Vapor Explosions or BLEVEs. 

Another interesting class of phase transitions is that of internal transitions within amphiphilic monolayers or bilayers. In particular, monolayers of amphiphiles at the air/water interface (Langmuir monolayers) have been intensively studied in the past as experimentally fairly accessible model systems [16,17]. A schematic phase diagram for long chain fatty acids, alcohols, or lipids is shown in Fig. 4. On increasing the area per molecule, one observes two distinct coexistence regions between fluid phases a transition from a highly diluted, gas -like phase into a more condensed liquid expanded phase, and a second transition into an even denser... 

This text is intended to provide an overview of methods for estimating the characteristics of vapor cloud explosions, flash flies, and boiling-liquid-expanding-vapor explosions (BLEVEs) for practicing engineers. The volume summarizes and evaluates all the current information, identifies areas where information is lacking, and describes current and planned research in the field. 

On January 4, 1966, at Feyzin refinery in France, a leak from a propane storage sphere ignited. The fire burned around the vessel and led to boiling liquid expanding vapor explosions. The accident caused eighteen deaths and eighty-one injuries. 

Reid, R. C. 1980. Some theories on boiling liquid expanding vapor explosions. Fire. March 1980 525-526. 

Venart, J. E. S. 1990. The Anatomy of a Boiling Liquid Expanding Vapor Explosion (BLEVE). 24th Annual Loss Prevention Symposium. New Orleans, May 1990. 

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