a. General. Detonators are explosive devices sensitive to mechanical initiation. They are used to detonate explosive charges. Detonators combine functions of firing devices and blasting caps in a single unit. They may or may not incorporate a time-delay mechanism. Detonators used in demolition work are classified according to initiating action as friction, percussion and concussion.

(1) Delay friction type. Delay friction detonators (fig. 8-7 and 8-8) consist of a cylindrical, olive-drab, plastic housing containing a pull wire coated with friction material. The pull wire is set in a flash compound. A tube set in the lower end of the housing contains either an 8-second or 15second delay fuse. The tube also contains a small detonator charge about the size of a blasting cap. Markings on the surfaces of the delay housings and the type of pull rings distinguish the 8-second and 15-second delay detonators. The 8-second type has a T-shaped pull ring; the 15-second type has a circular pull ring. With the safety pin removed, pulling on the pull ring draws the coated wire through the flash compound. The flash ignites the delay fuse. At the end of the delay period, the burning fuse initiates the attached detonator charge.

cap protector delay fuse detonator charge safety pin and rlng-

cap protector safety pin and rlng-

■ 5-3/8-in. ■

t-puil ring identifîe5 8-second delay delay fuse detonator charge

standard thread primer mixture standard thread

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