Millisecond delay blasting

See Fig. I. a Lypical quarry blast using a millisecond delay eleetric blasling cap. 

Fig. 1. Quam blast utilising high explosives initiated with electrical delay devices l millisecond delay electric blasting caps)...

The delayed-action detonators may be set for a delay of half a second (half-second detonators) or for a delay of 2-34 ms (millisecond detonators). Blasting with the latter type of detonators results in a larger yield of blasted stone fragments moreover, a smaller shock will be imparted to the ground around the explosion site. 

Non-electric, short-interval (millisecond) delay devices for use in delaying blasts which are initiated by detonating cord. 

P5 Explosives are designed for blasting solid coal with millisecond delay. 

Other important developments blasting supplies have been a " no-lag electric cap for seismic exploration , "millisecond (MS) delay electric blasting caps , " static resistant (SR) electric caps , "high temperature caps , "special oil-well detonators ,... 

Delay Element. This term may also be applied to a component which provides a specific delay in a blasting cap, detonator, fuze, etc Refs l)0hart (1946), 20 278 2)H.M.Kerr C.R.Hall USP 2560452 (1951) CA 46, 1259 (1952) [Delay elements for electric blasting caps consist of homogeneously mixed powdered metals (such as Mg, Al, Ni, Zn), fuels (such as Si), oxidizers (such as Pb C ) and Misch -metall . By varying the compns, burning times of 15 to 579 milliseconds were obtained] [The Misch-metall (Ger for mixed metal ) is an alloy of rare earths of the following compn ... 

Other important developments in blasting supplies have been a no-lag electric cap for seismic exploration , millisecond (MS) delay electric blasting caps , " static resistant (SR) electric caps , high temperature caps , "special oil-well detonators , "waterproof booster for exploding seismograph. sleeper charges in very deep holes , a "millisecond (MS) delay connector for delay firing of Prtmacord", " D eta prime Primers, and electric squibs for military and commercial uses (Ref 6, pp I6 87—99 also Ref 7, pp 6—7)... 

In the millisecond range, say from 25—1000 msec, the delay action provides for effective blasting in quarries, salt mines, and numerous other commercial applications of explosive charges. Staggering the explosions in series of boreholes reduces vibration and improves fragmentation. It has special advantages in grade construction work. ... 

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