Compression bursting

Many operators find it hard to grasp the power of compressed air. Section 2.2 (a) describes how the end was blown off a pressure vessel, killing two men, because the vent was choked. Compressed air was being blown into the vessel, to prove that the inlet line was clear. It was estimated that the gauge pressure reached 20 psi (1.3 bar) when the burst occurred. The operators found it hard to believe that a pressure of only twenty pounds could do so much damage. Explosion experts had to be brought in to convince them that a chemical explosion had not occurred. 

Fires have often occurred when air is compressed. Above 140°C, lubricating oil oxidizes and forms a carbonaceous deposit on the walls of air compressor delivery lines. If the deposit is thin, it is kept cool by conduction through the pipework. But when deposits get too thick, they can catch fire. Sometimes the delivery pipe has gotten so hot that it has burst or the aftercooler has been damaged. In one case the fire vaporized some of the water in the aftercooler and set up a shock wave, which caused serious damage to the cooling-water lines. 

The rapid expansion of a vessel s contents after it bursts may produce a blast wave. This expansion causes the first shock wave, which is a strong compression wave... 

In general, the following loads must be considered i.e., tension, collapse, burst and compression, and the reasonably worst working conditions ought to be assumed. 

New Explosive Co, Ltd. At Stowmarket, Engl, it was the first plant to manufacture compressed blocks of wet NC by Abel s method. These blocks were used as bursting charges in various projectiles as well as for demolition purposes. This facility also manufd Dynamites, Gelignite, Cordite, Carbonite, etc Ref Daniel (1902), 451... 

This is one of the simplest applications of the flow of a compressible fluid and it can be used to illustrate many of the features of the process. In practical terms, it is highly relevant to the design of relief valves or bursting discs which are often incorporated into pressurised systems in order to protect the equipment and personnel from dangers which may arise if the equipment is subjected to pressures in excess of design values. In many cases it is necessary to vent gases evolved in a chemical reaction. 

A further hazard exists when compressed air jets are used to clean machine components in workplaces flying particles have caused injury and blindness. Cylinders may fail if overpressurized or weakened by the application of heat. Liquefied gases, e.g. butane or propane, respond more rapidly to heat than the permanent gases such as nitrogen or oxygen. Cylinders are normally protected by pressure relief valves, fusible plugs or bursting discs. 

When the tube was operated as a shock tube (i.e. when detonation was initiated from a shock), a diaphragm of cellophane or photographic film was inserted in the union along with an Oring to seal the test chamber. To burst the diaphragm compressed He or H was fed into the reservoir section until rupture occurred. The burst pressure was read from... 

Stability. Lower explosive limit in air, 7.3% by volume sensitive to adiabatic compression (Angus Chemical Co., 1998) forms an explosive sodium salt which bursts into flame on contact with water (Budavari, 1998) Octanol/waterpartition coefficient (P) log P, -0.35 (Hansch et al., 1995) Conversion factor -, mg/m = 2.50 x ppm... 

Thus a layer of bursting charge adjfcent to the initiator is compressed more weakly and in consequence complete explosion occurs with greater ease. 

Towards 1938 a modification of this method was introduced under the name of the Armstrong Airbreaker [9], In this system the air is compressed up to 800 kg/cm2 and introduced by opening a blow-out valve this ruptures the bursting disk and blows up the shothole. 

---