Safety fuse testing

Because of the extreme importance of regularity and freedom from failure which must characterise safety fuse, detailed and exhaustive tests must be carried out on the product. Certain controls are obvious, namely, measurement of powder charge and of burning speed, both before and after immersion in water. Other tests usually carried out include resistance to cracking on flexing at low temperatures round a mandrel, coil tests in which the fuse is bunched into flat or complex coils and freedom from failure after immersion in water is determined. New types of fuse are usually tested to indicate the amount of smoke produced and also to determine the adequacy of the end spit. The end spit is the projection of particles of burning powder from a cut end and is of importance because it provides the mechanism which enables the fuse to ignite a detonator. 

Eye protection — safety glasses or goggles - is mandatory whenever any pyrotechnic composition is being prepared or tested. Necessary equipment includes a mortar and pestle, a laboratory balance, a soft bristle brush, several 2-3 inch lengths of fireworks-type safety fuse (available from many hobby stores), and a fireproof stone or composite slab on which to conduct burning tests. 

Place a small pile of the mixed composition on the fireproof board, insert a section of safety fuse into the base of the pile, and carefully light the end of the fuse with a match. Step back and observe the effect. Because of the generation of smoke by most pyrotechnic compositions, these tests are best conducted outdoors or in a well-ventilated area such as a laboratory fume hood. 3e certain no flammable materials are near the test area, for sparks may be produced. 

Determination of Heat Liberated on Explosion with Calorimeter (99-104) Lead Block Expansion Test (Trauzl Test) (104-06) Compression Tests with Small Lead Blocks (106-08) Testing of Detonators, which include Sand Test and Nail Test (108-14) Water Resistance of Electric Detonators (114-15) Testing Burning (Safety) Fuse (115-18) Testing Detonating Fuse (118-19)... 

Heats of Formation and of Explosion (33-41) Temperature of Explosion (41-8) Pressure of Explosion (49-58) Power by Trauzl Test (58-63) Brisance by Crusher Test (Stauchapparat) (64-5) Testing of Blasting Caps by Lead Plate Test (155-57) Testing of Blasting Caps by Pendulum Apparatus (157-59) Determination of Burning Time of Safety Fuses (163-65) ... 

Testing of "Burning Fuse , also known as Running Fuze and Safety Fuse) ... 

Fleischer Burtle (Ref 3) give results for a flame test for different types ofLead Azide. In this test a std safety fuse provides the flame and percent firing of the Lead Azides is recorded as a function of distance from the fuse as shown in the tabulation below ... 

Ease of Ignition by Flash Test (British). A portion of 3g of an explosive is placed in a short 3/8 inch diam test tube, and a piece of safety fuse is inserted in the middle of it. After igniting the upper end of the fuse, it is ohserved whether the expl deflagrates when the fuse bums down to it Ref Marshall 2(1917), p434... 

The rate of detonation of ammonium chlorate of density 0.9 g/cm3 is 3300 m/sec, and its expansion in the lead block test is about 250 cm3. Ammonium chlorate is sensitive to impact it explodes if a 2-kg weight is dropped on it from a height of 15-20 cm. It takes fire from the flame produced by a safety fuse, and if confined the flame causes it to explode. 

Sicherheitszundschnure = safety fuses 276 Silberacetylid 285 Silberazid 286 Silbercarbid 285 Silberfulminat 287 silver acetylide 285 silver azide 286 silver carbide 285 silvered vessel test 286 silver fulminate 287 single bases powders 287 SiNCO = qas qeneratinq propellant (german) 288... 

Heat sensitivity is determined by testing the flammability of explosives brought into contact with glowing objects, flame, sparks, the initiating flame of a black powder safety fuse, a red-hot iron rod, or a flame. 

Test safety fuse in fuse assembly to make sure it will not jet after being e-poxied in place. If it does, try another brand or epoxy the fuse at the dowel ends only. 

The test is conducted in the following manner 200 mg of hexogen are press-loaded at 1115 kp/cm in a polymethylmetacrylate (PMMA) holder. Above it, a primary explosive is filled in the state at which its initiating strength is to be tested freely poured or pressed to a desired density. The initiation of the primary explosive is performed by means of a safety fuse. If the depth of the dent produced after initiation in the steel witness plate of 70-90 Rockwell B hardness is greater than 0.76 mm, the complete detonation of hexogen is... 

Flash detonators, which are initiated a flame (e.g., safety fuse flame), should to be tested to the action of the open flame. 

Safety fuses may be used in the detonation of explosives where methods described in 15-3h(1) above cannot be accomplished. Safety fuse, when used, must be tested for burning rate at the beginning of each day s operation and whenever a new coil is used. Sufficient length of fuse shall be used to allow personnel to retire to a safe distance, but under no circumstances should a length be less than three feet or have less than 120 second burning time. Crimping of fuse to detonators must be accomplished with approved... 

V2O5-P205 (95 5, molar ratio) cathode and a lithium anode (Li/a-V205 cell) [1]. In this section, we describe safety test results for AA Li/a- V2Os cells. The AA cell we fabricated has a pressure vent, a Polyswitch (PS, Raychem Co., thermal and current fuse) and is composed of a spirally wound cathode sheet, a metallic Li-based anode sheet and a polyethylene (PE) separator [87]. 

Underwriters Laboratories (UL) requires that consumer batteries pass a number of safety tests [3]. UL requires that a battery withstand a short circuit without fire or explosion. A positive temperature coefficient (PTC) device [4] is used for external short-circuit protection. The resistance of a PTC placed in series with the cell increases by orders of magnitude at high currents and resulting high temperatures. However, in the case of an internal short, e.g., if the positive tab comes lose and contacts the interior of the negative metal can, the separator could act as a fuse. That is, the impedance of the separator increases by two to three orders of magnitude due to an increase in cell temperature. 

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