Shielding explosive material

Acetone cyanohydrin nitrate should be regarded as a moderately explosive material and should be handled carefully and distilled behind a safety shield. For purposes of comparison, the drop-weight sensitivities on the Olin-Mathieson drop-weight tester of three materials are propyl nitrate, 10 kg.-cm. acetone cyanohydrin nitrate, 40 kg.-cm. nitromethane, 60 kg.-cm. 

Nonexpendable light sources, such as a Q-switched pulsed laser can be protected. from destructive forces encountered in the photography of explosive material by piping the light through fiber optics, to the experimental zone. Occasionally lens systems are used to relay the light from mirrors located near a protective barrier shielding the laser (Ref 16)... 

It is a moderately explosive material of moderate impact-sensitivity. Use of a safety shield is advised for distillation. 

The preparation of this extremely explosive material is reported, It once exploded spontaneously on isolation. It is recommended that no more than 100 mg be handled, using face-shields, leather aprons, Kevlar gloves and Teflon spatulas. Some pentaazidotellurate(IV) salts were also prepared a yellow oil probably the crude tetramethylammonium salt exploded on stirring [1], Tellurium tetraazide was reported by another group at much the same time, they also prepared a hexaazido-tellurate (2-) as the bis(tetraphenylphosphonium) salt [2],... 

Shielding of Facilities for Work with Explosive Materials... 

A relatively new concept called suppressive shields is offered to provide protection to the area surrounding hazardous work with pyrotechnic and explosive material. At present, these operations are either limited to small quantities, widely dispersed, or segregated by barricades. Suppressive shields provide an alternative in the form of a vented steel enclosure. 

Group 6 Shield. The Group 6 Shield is spherical. The requirement for this shield is that an operator be capable of transporting on a push cart small quantities of extremely hazardous primary explosive material. It is not feasible to vent this shield because of the hazardous material Involved and the close proximity of the operator. 

The two foot diameter spherical steel shell shown in Figure U- is lA inch thick and weighs about 165 pounds. A rectangular tray is used Inside the shield to carry 10 cups of primary explosive material. Each cup contains TO grams of lead azide in a typical application. Total weight of explosive is limited to 700 grams lead azide or equivalent (1, 3. ... 

A fixture for mechanical function testing is photographed in Figure 6. It Illustrates the attachment of the shield to the barricade. The operator rolls the cart up to the barricade where a clamp is closed and the shield is locked to the barricade. Transport mechanisms shown behind the barricade remove the tray with explosive material from the shield. At no time is the operator exposed to explosive hazards. 

Blast overpressure was recorded inside and outside the shield when explosive material was detonated in the shield. High speed motion picture coverage was included on all shots. Video display of each test in the instrument building was also recorded. 

Dimethyl azodicarboxylate (manufactured by Tokyo Kasel Kogyo Co., Japan) was purchased from CTC Organic, 792 Windsor Street, Atlanta, GA 30315. Overheating of dimethyl azodicarboxylate should be avoided because of the danger of explosion. Distillation should be conducted from a temperature-controlled bath in the hood behind a safety shield. The material used distilled at 71-72°C (2 mm), at a bath temperature of 84-86°C. It is important that the addition of this compound to the reaction mixture be carried out at a constant rats without Interruption because it tends to freeze in the syringe needle. The checkers explored the use of diethyl azodicarboxylate because of its lower cost and wider availability. However, the corresponding hydrazine derivative Is more difficult to separate from the -lactone product of this step. 

Work with explosive (or potentially explosive) materials generally requires the use of special protective apparel (e.g., face shields, gloves, and laboratory coats) and protective devices such as explosion shields, barriers, or even enclosed barricades or an isolated room with a blowout roof or window (see Chapter 6, sections 6.F.1 and 6.F.2). Before work with a potentially explosive material is begun, the experiment should be discussed with a supervisor or an experienced co-worker, and/or the relevant literature consulted (see Chapter 3, sections 3.B.2, 3.B.5, and 3.B.6). A risk assessment should be carried out. 

Shielding. Any material or obstruction, including terrain, that absorbs radiation and thus tends to protect personnel from the effects of atomic explosion. A moderately thick layer of any opaque material will provide satisfactory shielding from thermal radiation, but a considerable thickness of high-density material—e.g., lead—may be needed for protection from nuclear radiation. Concrete and water absorb the energy of gamma rays and neutrons. 

Equipment which produces microwave radiation can usually be shielded to protect the users. If size and function prohibits this, restrictions on entry and working near an energised microwave device will be needed. Metals, tools, flammable and explosive materials should not be left in the electromagnetic field generated by microwave equipment. Appropriate warning devices should be part of the controls for each such appliance. Commercially-available kitchen equipment is subject to power restrictions and controls over the standard of seals to doors, but regular inspection and maintenance by manufacturers is required to ensure that it does not deteriorate with use and over time. 

When dispersed as a dust, adipic acid is subject to normal dust explosion hazards. See Table 3 for ignition properties of such dust—air mixtures. The material is an irritant, especially upon contact with the mucous membranes. Thus protective goggles or face shields should be worn when handling the material. Prolonged contact with the skin should also be avoided. Eye wash fountains, showers, and washing faciUties should be provided in work areas. However, MSDS Sheet400 (5) reports that no acute or chronic effects have been observed. 

Mitigate the effects of fire or explosion, e.g. by deteetion provision, spaeing, appropriate eonstmetion materials, shielding, venting, extinguishment, provision for evaeuation of personnel. 

Caution The nitrating mixture consisting of fuming nitric acid and acetic anhydride is an extremely active one, and combinations of it and organic materials are potentially explosive. The nitration should be carried out behind adequate safety shields. Acetone cyanohydrin nitrate is moderately explosive (Note 6) and all operations with it, but particularly its distillation, should be carried out behind safely shields. 

Hydrogen cyanide is highly endothermic and of low MW (AH°f (g) +130.5 kJ/mol, 4.83 kJ/g). A comprehensive guide to all aspects of industrial handling of anhydrous hydrogen cyanide and its aqueous solutions states that the anhydrous liquid is stable at or below room temperature if it is inhibited with acid (e.g. 0.1% sulphuric acid) [ ] Presence of alkali favours explosive polymerisation [2], In absence of inhibitor, exothermic polymerisation occurs, and if the temperature attains 184°C, explosively rapid polymerisation occurs [3], A 100 g sample of 95-96% material stored in a glass bottle shielded from sunlight exploded after 8 weeks [4], The explosive polymerisation of a 33 kg cylinder was attributed to lack of sufficient phosphoric acid... 

The extreme hazards involved in handling this highly reactive material are stressed. Freshly distilled material rapidly polymerises at ambient temperature to produce a gel and then a hard resin. These products can neither be distilled nor manipulated without explosions ranging from rapid decomposition to violent detonation. The hydrocarbon should be stored in the mixture with catalyst used to prepare it, and distilled out as required [1], The dangerously explosive gel is a peroxidic species not formed in absence of air, when some l,2-di(3-buten-l-ynyl)cyclobutane is produced by polymerisation [2], The dienyne reacts readily with atmospheric oxygen, forming an explosively unstable polymeric peroxide. Equipment used with it should be rinsed with a dilute solution of a polymerisation inhibitor to prevent formation of unstable residual films. Adequate shielding of operations is essential [3],... 

The fourth column presents the radius of 50% mortality by thermal burns. The fireball from a nuclear explosion can reach temperatures in the tens of millions of degrees Fahrenheit and cause thermal burns at large distances. This intense heat can also cause temporary or permanent blindness and can ignite materials far from ground zero. Heat from the fireball will be felt instantly in all directions from ground zero thus, the longer a person remains out in the open, the more intense the thermal burns will be. However, the heat from the fireball lasts only several seconds and can be shielded by solid materials like brick and earth (e.g., behind a wall or hill, in a ditch or subway tunnel, etc.). The risk of thermal burns drops with increased distance from ground zero. 

Thus, every fraction of a second in the open increases radiation dose and the likelihood of serious thermal burns. The instant an individual realizes that a nuclear explosion has occurred, he should place as much solid material between his position and the rising fireball. The solid material can be a concrete or brick wall, deep ditch, building (preferably not constructed of glass), or anything that can act as a shield against radiation and heat. 

Time and shielding can be merged into a single factor. The shelters described in Section 5.2.1 (walls, basements, etc.) really serve as shields from radiation, heat, fallout, and even from the air blast and flying debris. At the moment of explosion, radiation and heat travel at the speed of light and expose unshielded victims. At the instant of realization that a nuclear weapon has exploded, an individual should move as quickly as possible to a location behind a rugged shielding material. 

Shielding material can be brick, concrete, steel, wood, or even the earth. Ideally, the shielding material will not collapse from the explosion or air blast or burn from the heat. If available, an underground shelter is the best option to avoid the air blast, thermal burns, initial radiation, and fallout. However, most victims do not have time to be terribly selective about where to seek shelter. The innermost rooms of a building may be the only shelter available. While they do not provide the same level of shielding as an underground basement, they provide more protection than an open environment. Seek the best shield in the immediate vicinity and stay there at least several minutes until the initial radiation and heat subside. 

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