Flash relief

The same patient taken during the same consultation (a) without flash and (b) with flash relief and lip wrinkles are flattened by the effect of the flash. The nasolabial folds, on the other hand, are more clearly visible with flash. 

Check metallurgy for light hydrocarbons flashing during relief. Very low temperatures can be produced. 

A vapor poeket on the exchanger s low-pressure side can create a cushion that may greatly diminish the pressure transient s intensity. A transient analysis may not be required if sufficient low-pressure side vapor exists (although tube rupture should still be considered as a viable relief scenario). However, if the low-pressure fluid is liquid from a separator that has a small amount of vapor from flashing across a level control valve, the vapor pocket may collapse after the pressure has exceeded the fluid s bubble point. The bubble point will be at the separator pressure. Transient analysis will prediet a gradually inereasing pressure until the pressure reaches the bubble point. Then, the pressure will increase rapidly. For this ease, a transient analysis should be considered. 

Fauske [32] represented a nomograph for tempered reaetions as shown in Figure 12-35. This aeeounts for turbulent flashing flow and requires information about the rate of temperature rise at the relief set pressure. This approaeh also aeeounts for vapor disengagement and frietional effeets ineluding laminar and turbulent flow eonditions. For turbulent flow, the vent area is... 

Local rapid flashing, rupture disc/relief valve inadvertently open, release to stack Stack height designed to dissipate release 4 ... 

Huff, J. F., 1985, Multiphase Flashing Flow in Pressure Relief Systems, Plant Operations, 4, 191-199. 

A visible cloud of vapor, 1 m deep, spread for 150 m and was ignited by a car that had stopped on a nearby road 25 minutes after the leak started. The road had been closed by the police, but the driver approached from a side road. The fire flashed back to the sphere, which was surrounded by flames. There was no explosion. The sphere was fitted with water sprays. But the system was designed to deliver only haif the quantity of water normally reeommended (0.2 U.S. gal/ft- min. or 8 L/m min.), and the supply was inadequate. When the fire brigade started to use its hoses, the supply to the spheres ran dry. The firemen seemed to have used most of the available w ater for cooling neighboring spheres to stop the fire from spreading, in the belief that the relief valve would pro-teet the vessel on fire. 

The calculation method can be selected by application of the decision tree in Figure 9.2. The liquid temperature is believed to be about 339 K, which is the temperature equivalent to the relief valve set pressure. The superheat limit temperatures of propane and butane, the constituents of LPG, can be found in Table 6.1. For propane, T, = 326 K, and for butane, T i = 377 K. The figure specifies that, if the liquid is above its critical superheat limit temperature, the explosively flashing liquid method must be chosen. However, because the temperature of the LPG is below the superheat limit temperature (T i) for butane and above it for propane, it is uncertain whether the liquid will flash. Therefore, the calculation will first be performed with the inclusion of vapor energy only, then with the combined energy of vapor and liquid. 

The driver of the tank truck decided to take the coastal route to Puerto-tollano, which passed close to several campsites. During the journey, the pressure in the tank built up and, because of the absence of a pressure relief valve, the weakened tank cracked. The propylene that was released ignited, and a flash fire burned near the tank. Eventually this ruptured and an explosion occurred close to a campsite, killing 210 people. 

Another required safety feature on water heaters is a temperature and pressure relief valve. This is mounted near or on top of the tank. The temperature and pressure valves are designed to vent water if the temperature or pressure in the tank becomes too high. If there is no relief valve and the controls fail to limit water temperature, there is a danger of a powerful explosion from superheated, pressurized water flashing to steam as the water heater bursts. 

First K. E. and J. E. Huff, Design Chaits for Two-Phase Flashing Flow in Emergency Pressure Relief Systems, Plant Operations Progress, Vol. 8, No. 1, 1989, p. 40. 

The flash vessel should be fitted with a float or inverted-bucket type steam trap to the condensate discharge line, and also a pressure relief valve to prevent excess pressure buildup, as may happen if the demand for LP steam drops below the flash steam production rate. 

Many women seek medical treatment for the relief of menopausal symptoms, primarily hot flashes however, the role of hormone-replacement therapy (HRT) has changed dramatically over the years. HRT has long been prescribed for relief of menopausal symptoms and, until recent years, has been purported to protect women from CHD. The original reason behind recommending HRT in postmenopausal women revolved around a simple theory If the hormones lost during menopause were replaced through drug therapy, women would be protected from both menopausal symptoms and chronic diseases that often follow after a woman experiences menopause. Recent studies have disproved this theory. 

Inspections Flash Arresters, Relief Devices Hazards Manual Toxicity, Flammability, Reactivity,... 

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