Bumping, of liquids

Bucherer hydantoin synthesis, 843, 844 Bucherer reaction, 561, 568, 569 Bumping of liquids, 3, 4... 

The heat transfer oil control valve was leaking. Unknown to the operators, the boiler temperature rose from 75°C to 143°C, the boiling point of the contents. Finally, bumping in the boiler caused about 0.2 ton of liquid to be discharged through the vent. 

A report is given of explosion of a tank containing 7000 t of liquid ammonia, in Lithuania, consequent upon thermal disequilibrium and bumping of the liquid [10,11], The liberated ammonia caught fire in the open air, the first time this is thought to have been observed. 

Distilling flasks should be chosen of such a size that the bulb is half or two-thirds full of liquid. In order to avoid bumping and superheating a few pieces of porous plate (pot) half as large as peas are dropped into the flask before each distillation. If boiling is again delayed fresh pieces of pot must be added, not to the superheated liquid, however, but after brief cooling. 

A Boiling Liquid Expanding Vapour Explosion, or BLEVE, is an industrial event related to the laboratory bump occasioned when the inadequately mixed bottom of a vessel of liquid becomes superheated, then explosively boils. In the industrial version, rupture of a pressurised container is usually involved. Although strictly speaking a non-reactive physical hazard, chemical fires and explosions, with fatalities, often follow. Means of estimating risk and prevention, with a fist of incidents are given[l], A more ferocious version, the Boiling Liquid Compressed Bubble... 

Ignition Caused by Compression of Liquids. Liquids can be ignited by sudden compression. This can happen when there is water hammer caused by the pressure surge from quick-acting valves and from the compression in liquid pumps. Sudden compression can occur with liquids, for example if a tank car is bumped rapidly and the liquid goes to one end very quickly, possibly trapping some vapor bubbles that compress and create local hot spots that can cause ignition. 

To change the pressure in the system between measurements, first remove the heating mantle. After a short time, admit some air or remove some air by opening stopcock S for a few seconds. Be especially careful in removing air from the ballast bulb to avoid strong bumping of the hot liquid. Check the pressure. Repeat as often as necessary to attain the desired pressure, and then restore the heating mantle to its position under the flask. 

This is also known as short-path distillation or bulb-to-bulb distillation. It is a procedure for reduced-pressure distillation, which almost eliminates losses owing to the size of the apparatus, and is particularly useful for small volumes of liquids. The liquid sample is placed in a small round-bottom flask, connected to a series of bulbs (Fig. 15.6) and then heated and rotated (to prevent bumping)... 

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