blasting cap

1. n. [Well Completions, Geophysics]
A small, electrically activated explosive charge that explodes a larger charge. Detonators, also called caps, seismic caps or blasting caps, are used for seismic acquisition with an explosive source to achieve consistent timing of detonation.
See: cap, detonator
2. n. [Well Completions, Geophysics]
A device containing primary high-explosive material that is used to initiate an explosive sequence. The two common types of detonators are electrical detonators (also known as blasting caps) and percussion detonators. Electrical detonators have a fuse material that burns when high voltage is applied to initiate the primary high explosive. Percussion detonators contain abrasive grit and primary high explosive in a sealed container that is activated by a firing pin. The impact force of the firing pin is sufficient to initiate the ballistic sequence that is then transmitted to the detonating cord. Several safety systems are used in conjunction with detonators to avoid accidental firing during rig-up or rig-down. Safety systems also are used to disarm the gun or ballistic assembly if downhole conditions are unsafe for firing.