Explosion meter tests

On the afternoon of the second day, a crew of two machinists and a welder were assigned to disconnect the pump from the discharge piping. A hot work permit was issued, after explosion meter tests were conducted at a nearby coupling to ensure that the piping did not contain any flammables. 

How did a flammable gas enter the pump/piping system Why did the explosion meter tests prove negative What was the fuel within the pump Jobs similar to this were repeated over the past 50 years. Why did it happen at this particular time ... 

Investigators used an adjacent pump of the same detail and size to inspect for methane accumulation. A small flow of well water was routed to the gland on an idle sister pump for more than a day. The explosion meter tests performed after a day revealed that there was sufficient accumulation of methane to be troublesome. 

The deflagration flame arrester must he subjected to a series of at least 10 explosion (deflagration) tests in a rig with a pipe at least 5 feet (1.5 meters) long with various mixtures of propane in air and different test conditions to test the entire spectrum of possible deflagrations. Also, a series of 3 flashback tests, using a mixture of 4.2 volume percent of propane in air, must be conducted. 

A deflagration can best be described as a combustion mode in which the propagation rate is dominated by both molecular and turbulent transport processes. In the absence of turbulence (i.e., under laminar or near-laminar conditions), flame speeds for normal hydrocarbons are in the order of 5 to 30 meters per second. Such speeds are too low to produce any significant blast overpressure. Thus, under near-laminar-flow conditions, the vapor cloud will merely bum, and the event would simply be described as a large fiash fire. Therefore, turbulence is always present in vapor cloud explosions. Research tests have shown that turbulence will significantly enhance the combustion rate in defiagrations. 

A multi-disciplined team interviewed witnesses and performed tests, and the evidence was followed to a sound conclusion. Investigators sent the explosion meters (flammable gas detectors) to the instrument shop for examination. The welding torch was also inspected. Experts found both the torch and the meter behaved satisfactorily. There was speculation that some aquatic life deteriorated and formed methane, but that was not the case. They concluded that the fuel was dissolved methane from the well water system that was routed to the pump seal. Trace amounts of dissolved methane (about 0.02 percent by volume) accumulated in the well water stream flowing through the 3/8-inch-diameter stream on the... 

A multidisciplined team interviewed witnesses and performed tests, and the evidence was followed to a sound conclusion. Investigators sent the explosion meters... 

Nuclear reactors, however, do generate highly radioactive waste. This waste, which consists primarily of the fission fragments and their radioactive-decay products, must be stored for many years before its radioactivity decays to a reasonable level, and the safe long-term storage of this waste is a matter of great concern and debate. Fortunately, the volume of waste that is created is only about 20 cubic meters annually from a reactor, compared with 200,000 cubic meters of waste ash from a coal-fired plant. When nuclear weapions were tested in the atmosphere, the radioactive products from the nuclear explosions were released into the air and fell to Earth as radioactive fallout. 

Using a nomograph requires only the vessel volume in meters, selecting the dust class. St-1, St-2 or St-3 from Table 7-28. Using Tables 7-29 or 7-30 select the Kst value determined experimentally. The reduced pressure, Pfed. (maximum pressure actually developed during a vented deflagration, termed reduced explosion pressure) must not exceed strength of vessel (see earlier discussion) and the Psut, i.e., the vent device release pressure. Note that the static activation pressure, Pjj, must be determined from experimental tests of the manufacture of relief panels such as rupture disks. 

Measurement of Acidity or Alkalinity of Explosives. (Measurement of pH value). These tests consist essentially of extrg the sample of expl with w (either cold in the case of liquids such as NG, or hot for solids such as TNT, Tetryl, PA, etc), and detg the acidity of the resulting extr either by titration, colorimetric methods or by means of a pH meter. These tests are described under the individual compds... 

The apparatus used to determine the explosive nature of vapors is shown in Figure 6-14. The test procedure includes (1) evacuating the vessel, (2) adjusting the temperature, (3) metering in the gases to obtain the proper mixture, (4) igniting the gas by a spark, and (5) measuring the pressure as a function of time. 

Marshall 2(1917) Falling Weight Test (Lenze) (p 423) Friction Sensitivity Test (423) Sensitiveness to Detonation (429) Sensitiveness to Heat (434) Ignition Temperature (434) Heat of Explosion (440) Trauzl Test (469) Strength by Ballistic Pendulum (473) Velocity of Detonation by Dautriche Method (479) Brisance Meter of Hess (495)... 

Different laboratories use different criteria for determining whether a drop-test resulted in an explosion ( go ) or failure ( no-go ). In many test facilities any visual observation of smoke, flash or flame, or any crackle, pop or bang detected by the operator is taken to signify a go result. Sometimes sound-meters are used to detect the audible signals of a drop test. In still more elaborate tests, the volume of gas, produced by a go result, is measured. In general, for sensitive explosives like PETN, distinguishing between go ... 

Blast action is such that, for an oxygen balanced expl, the heat of expln appears to be propagated thru the medium (such as air) in the form of a shock wave, or at least BLE-He (heat of explosion). For a negatively balanced compn, or one in which after-reactions (usually exothermic) can occur, BLE-He + A where A is the heat of the after-reaction. In air, the after-reaction of most importance is the air-oxidation of unoxidized portions of the charge especially of the exothermic elements like Al. When the same elements are oxidized under water by CO2 or H20, it is part of He Blast effects can be tested by various methods such as listed in Vol 2, pp B2I4-R ft B215-L, under Blast Meters... 

He found hexanitrodiphenylamine to be slightly less sensitive in the drop test than tetryl and tetranitroaniline. When 1 pound of the explosive was loaded into a 3.5-inch cubical box of cardboard or tin and fired at with a U.S. Army rifle from a distance of 30 yards, hexanitrodiphenylamine gave no detonations in the cardboard boxes, and 7 detonations and 1 failure in tin TNT gave no detonation in cardboard, fire and detonation in tin and tetryl and tetranitroaniline gave detonations in every case with either kind of container. Marshall reported the velocity of detonation of hexanitrodiphenylamine to be 6898 meters per second at density 1.58, and 7150 meters per second at density 1.67. Pellets of the explosive, mixed with 1 per cent of stearic acid, compressed at 5000 pounds per square inch, had a density 1.43, at 10,000... 

Taylor and Rinkenbach found that 0.05-gram portions of hexa-methylenetriperoxidediamine, pressed in No. 8 detonator capsules under a pressure of 1000 pounds per square inch and fired by means of a black-powder fuse crimped in the usual way, caused the detonation of ordinary 40% nitroglycerin dynamite and of a gelatin dynamite which had become insensitive after storage of more than a year. The velocity of detonation of HMTD, loaded at a density of 0.88 in a column 0.22 inch in diameter, was found by the U. S. Bureau of Mines Explosives Testing Laboratory to be 4511 meters per second. 

The parameter which is measured in this test is the pressure of underwater explosion. Lead or copper membranes are employed, and the membrane deformation as a function of the performance of the explosive and of the distance from the explosion site is estimated. The measuring apparatus, consisting of piston and anvil, resembles the Kast brisance meter. An alternative technique is to measure the deformation of diaphragms or copper discs accommodated inside an air-containing vessel such as a can. 

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