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In explosive manufacturing, use, or related processes, there exist a variety of failure and hazard scenarios dependent upon the specific application, circumstances, equipment and/or materials involved. The following tests are required in some regulatory applications and have wide application in many differing environments. They are usually identified as necessary to resolve issues discovered during the hazards analysis of existing or proposed facilities, process, or products.
Bonfire
One of the many applications for this type of test is the UN Stack Test: A stack of packages of an explosive product or a stack of non-packaged articles is placed on a non-combustible surface (steel grate) above a lattice of dried wood wetted with diesel fuel. Sufficient wood is used to provide a 30 minute fire. Three aluminum screens are placed 4 meters from the edge of the stack. The fire is ignited and the material is observed for a) Evidence of detonation, deflagration or explosion of the total contents; b) Potentially hazardous projections; and c) Thermal effects (i.e. size of the fireball, etc.).
The standard test for transportation classification is conducted on materials or articles as they are intended to be packaged for transport to determine the hazards caused by an external fire. For in-process classification purposes, the test is used to see how a pile of unpackaged articles or substances in containers used for staging, process and/or onsite storage will react in a fire scenario. A pile or stack of an explosive product is placed on a non-combustible surface (steel grate) above a lattice of dried wood wetted with kerosene. Sufficient wood is used to provide a 30-minute fire. Aluminum screens are placed 4 meters from the edge of the stack when potential projectiles are present. The fire is ignited and the material is observed for: a) Evidence of detonation, deflagration or explosion of the total contents; b) Potentially hazardous projections; and c) Thermal effects (i.e. size of the fireball, etc.).
Reference: Transport of Dangerous Goods - Tests and Criteria
Bullet Impact
This test is used to measure velocities that result in reaction. Various slug and powder loading may be used. This test is applicable to solid propellant, base grains, uncured propellants, and explosives.
The sample is placed in a pipe with a threaded cap at both ends. A 0.30 caliber bullet is fired from 30 yard. Explosives which burn are considered satisfactory. Those that don't are more desirable.
This test is used to evaluate the response of an explosive to the kinetic energy transfer associated with the impact and penetration by a given energy source. The test sample is subjected to a three-round burst fired at 856 m/sec velocity and 600 rounds/min rate of fire. Typically the test is repeated in three different orientations. The striking point for the multiple impact is selected so that the impacting rounds penetrate the most sensitive material and location. A post-test inspection of the test film and hardware is performed to evaluate the reaction.
Closed Bomb
The result of this test is a pressure / time plot. The vessel is capable of withstanding gun pressures. SMS can provide closed bomb testing in several sizes and for varied applications. The bomb has firing electrodes to affect ignition, a gas relief valve, and a pressure transducer.
Critical Diameter-Standard
This test is used to establish an explosive's minimum dimension for propagating explosive reactions. This test consist of a metal pipe (schedule 40, seamless, class B, black, type A-53) of various inside diameters and varying lengths. The length is three times the diameter. Comp C-4 is used as a booster. Normally, the test shall be completed after three to five failures are obtained 0.25 inches below a diameter that has been previously detonated or propagated. This dimension is referred to as the critical diameter. Velocity probes, witness plates or other witness systems are used for detection.
Critical Diameter-Wedge
This test is used to determine the critical diameter of cured explosive. Critical diameter is defined as the diameter below which the propellant will not sustain propagation of a detonation. The sample is a rectangle bar of explosive with the aft end perpendicular to the sides, the forward end cut to a 370 angle (see Figure). Comp C-4 with width and thickness identical to sample end view, length tree times the end dimension plus 0.5 inch, packed to a density of 1.5 grams/cc is placed on the sample. The Comp C-4 is fired, as the detonation progresses toward the opposite end, the sample dimension decreases until the size no longer is sufficient to support propagation of the detonation reaction. The point at which propagation discontinues is used to calculate critical geometry and thus critical diameter.
Critical Height
This test is used to determine the critical height at which a low rate reaction transits to a higher order explosive reaction. This test consists of an igniter (flame) to supply the initial reaction and a variety of lengths and diameters of iron pipe to contain the test material. Using the same diameter, the height of the test material is progressively changed until the reaction goes from burning to explosion or detonation. The diameter is then changed and the progressive height change testing repeated.
A critical height test determines the burning distance that a substance requires in order to have an explosion. The test pipe for a critical height test is a schedule 40, mild steel, seamless pipe with a mild steel threaded cap on one end . Critical heights can be determined for different diameter pipe. A 12 gram bag igniter is placed at the bottom of the test pipe (in threaded cap), with ignition wires running up the inner length of the pipe to the top of pipe (open end). The test pipe is filled to within an inch of the top with propellant powder. The results of the tests are determined by inspection of the pipe apparatus. The test is concluded by running a minimum of three succeeding trials which produced a "no-go" result at a certain height level below a level which produced a positive reaction (explosion). This level is referred to as the critical height.
Deflagration to Detonation
This test is used to determine the tendency of a substance to undergo transition from deflagration to detonation. In this test, the sample substance to be tested is contained in a carbon steel pipe, capped at one end with a "3000 pound" forged steel pipe cap, and at the other with a 13 cm square, 8 mm thick mild steel witness plate which is welded to the pipe. A 5.0 g black powder igniter, with a nickel-chromium resistance wire loop attatched, is placed at the center of the vessel with the resistance wire loop attached to two insulated copper lead wires. These lead wires are fed through small holes in the wall of the pipe and sealed with an epoxy resin. The tube is placed in a vertical position and the igniter is fired by a 15 amperes current from a 20-volt transformer. Three trials are performed unless a deflagration to detonation transition occurs earlier. The test result is considered positive if a hole is punched through the witness plate.
Reference: Transport of Dangerous Goods - Tests and Criteria
Detonation Velocity
The result of this test is a pressure / time plot. The vessel is capable of withstanding gun pressures. SMS can provide closed bomb testing in several sizes and for varied applications. The bomb has firing electrodes to affect ignition, a gas relief valve, and a pressure transducer.
Drop Test
This test is used to determine if a finished or unfinished article can withstand a free-fall impact without producing any significant fire or explosion hazards. The test is not intended to evaluate whether the unit can withstand the actual impact. The article is dropped at an orientation in which they are most likely to function on impact. Three drops are made on the unit unless a decisive event (e.g. fire or explosion) occurs earlier. A test result is considered positive if evidence of initiation is identified. A rupture of the casing alone is not considered a positive result.
Reference: Transport of Dangerous Goods - Tests and Criteria
EIDS Gap
This test is used to measure the sensitivity of an EIDS candidate to a specified shock level, i.e. specified donor charge and gap. The test consists of an explosive charge (donor), a barrier (gap), a container holding the test charge (acceptor), and a steel witness plate (target). A clean hole punched trough the plate indicates that a detonation was initiated in the sample, and a substance which detonates in any trial is not an EIDS.
EPA Office of Solid Waste Test Method 1030
For the preliminary screening test, an unbroken strip or powder train about 250 mm long by 20 mm at the base and 10 mm high is placed on a low heat-conducting plate. A gas flame (burner torch) is used to ignite the powder train at one end (minimum temperature 1000°C). If the material does not ignite within two minutes or takes longer than two minutes to burn 200 mm of the powder train, it is not considered a flammable solid. If the material ignites and propagates by either flame or smoldering through a 200 mm length in less than two minutes, a full series of tests must then be conducted to determine the burn rate. If the burn rate is greater than 2.2 mm/sec then the material is considered to be a flammable solid.
Free Fall Impingement
Gel Permeation Chromatography (GPC)
Gel Permeation Chromatography (GPC) is used to determine the amount of a reference sample in a given material. The reference sample is extracted from the material using a solvent and separated from the insoluble material using a combination of techniques (centrifuging, filtering, etc.). The extracted solution is separated from lower molecular weight compounds by injecting the extracted solution onto separation columns packed with porous material. A steady flow of solvent on the column system moves the sample through the columns.
As the compounds in the sample pass through the packing, the smaller sized compounds are delayed in the pores of the packing while the larger sized compounds are excluded from the pores and travel faster. The result is a size (or molecular weight) separation where the larger sized compounds exit the column system first followed by the smaller compounds. A refractive index (RI) and/or UV-detector are used to detect compounds as they exit the column system. A reference-sample standard of known concentration is used to convert the detector response to concentration and quantify the amount present.
Heat of Combustion
Heat of Reaction
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