Scaled Overpressure:
$$p_s = p/p_a $$
|
$p$
|
Overpressure (Pa)
|
|
$p_a$
|
Atmospheric Pressure (Pa)
|
Sachs Scaled Distance:
$$\bar{R} = R /(h_{combustion} \cdot V/p_a)^{1/3} $$
|
$R$
|
Radius ($m$)
|
|
$h_{combustion}$
|
Heat of combustion of stoichiometric hydrocarbon-air mixture ($J/m^3$)
|
| $V$
|
volume of congested area (or in the case of DDT entire flammable cloud volume) ($m^3$)
|
| 2D Flame Expansion |
Obstacle Density |
| High |
Medium |
Low |
| Reactivity |
High |
DDT |
DDT |
0.59 |
| Medium |
1.6 |
0.66 |
0.47 |
| Low |
0.66 |
0.47 |
0.079 |
| 2.5D Flame Expansion |
Obstacle Density |
| High |
Medium |
Low |
| Reactivity |
High |
DDT |
DDT |
0.47 |
| Medium |
1.0 |
0.55 |
0.29 |
| Low |
0.50 |
0.35 |
0.053 |
| 3D Flame Expansion |
Obstacle Density |
| High |
Medium |
Low |
| Reactivity |
High |
DDT |
DDT |
0.36 |
| Medium |
0.50 |
0.44 |
0.11 |
| Low |
0.34 |
0.23 |
0.026 |
References
- Baker, Q.A., M.J. Tang, et al. (1994), Vapor Cloud Explosion Analysis, 28th Loss Prevention Symposium, Atlanta, GA. American Institute of Chemical Engineers.