This document was originally presented at the Chapter’s 1999 workshop.

It was revised and re-published as a newsletter supplement in 2008.

(Click on the above title to open a copy of the document.)

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Originally presented at the GW Chapter’s workshops in 2006 and 2007.

(Click on the title to open a copy of the document.)

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Useful Calculations and Conversion Factors for Blasters:

Official Metric Equivalents (according to U.S. and Canadian law):

1 inch (in.)             =    25.4 millimeters (mm)

1 pound (lb.)         =    453.59237 grams (g)

Conversion Factors:

 Distance: feet (ft) x 0.3048 = meters (m) meters x 3.2808 = feet Weight: pounds (lbs) x 0.4536 = kilograms (kg) kilograms x 2.2026 = pounds Peak Particle Velocity: in/sec x 25.4 = mm/sec mm/sec x 0.3937 = in/sec Volume: cubic yards (yd3) x 1.308 = cubic meters (m3) cubic meters x 0.7645 = cubic yards Powder Factor: lbs/yd3 x 0.93 = kg/m3 kg/m3 x 1.6863 = lbs/yd3 Square Root Scaled Distance: ft/lbs1/2 x 0.45236 = m/kg1/2 m/kg1/2 x 2.2106 = ft/lbs1/2 Cube Root Scaled Distance: ft/lbs1/3 x 0.3965 = m/kg1/3 m/kg1/3 x 2.5221 = ft/lbs1/3 Pressure: lbs/in2 x 0.145 = Pascals Pascals x 6.895 = lbs/in2 lbs/in2 x .0000689 = kilobars* kilobars* x 14504 = lbs/in2 feet of water x 0.434 = lbs/in2 lbs/in2 x 2.31 = feet of water

*  1 Bar  =  14.5 lbs/in2

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Other miscellaneous calculations:

Pounds of explosive loading per foot of borehole  =  D2  x  S.G.  x  0.34*

Where:

D       =   explosive diameter

S.G.   =   specific gravity of explosive (g/cc)

*   In the above formula, the factor 0.34 is used to convert g/cc to lbs/cu ft and to calculate the

volume of the explosive charge.     It is the result of the equation,

0.7854  x 12  x  62.4

1728

where:                    0.7854 = ¼ of pi

12 = the number of inches in a foot

62.4 = the weight of 1 cubic foot of water in lbs (at approximately 45oF)

1728 = the number of cubic inches in a cubic foot

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Displacement of water in a borehole:         H  =  D2 / (D2 – De2)  x  h

Where:

H  =   final height of water

h  =   initial height of water

D  =   hole diameter

De  =   explosive cartridge diameter

Determine H, the final height of water, and then divide H by the cartridge length to

determine the number of cartridges that will be required to build out of the water.

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Square Root Scaled Distance (Ds)    =    Distance / Explosive Weight1/2

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The following equations express the relationships between Velocity, Displacement,

Frequency and Acceleration for sinusoidal waveforms.

V  =  2 π  f  D                or             V  =  386.1 Gs / (2 π f)

D  =  V  /  (2 π f)

A  =  2 π  f  V         or            Ag  =  (2 π  f  V) / 386.1

f  =  V / (2 π D)      or            f  =  A  / (2 π V)

Where:

V  =  velocity in inches/second

D  =  peak displacement in inches

A  =  acceleration in inches/second/second (in/sec2)

Ag  =  acceleration in Gs

f  =  frequency in Hertz (cycles per second)

π (pi)  =  3.14159….

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Cole’s formula for determining peak pressure from an explosive charge detonating

underwater (assumed TNT or its equivalent):

P  =  2.25 x 104 (W1/3 / R) 1.14

Where:

P  =  peak pressure in psi

W =  explosive charge weight in pounds

R  =  distance in feet from the detonating charge

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