Useful Calculations and Conversion Factors for Blasters
Official Metric Equivalents
(according to
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
*************
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
*************
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.
*************
Square Root Scaled Distance (Ds) =
Distance / Explosive Weight1/2
*************
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….
*************
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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