// Calculate energy of blast (3.5 Mj/m3 is an average for most hydrocarbons)
$E = [VCV:m3] * 3.5e6;
// Calculate scaled pressure
$Ps1 = [ePd:Pa] / [PA:Pa];
// Return if scaled pressure is not possible
if ($Ps1 > 0.05) return NULL;
// Calculate scaled distance (for class 10)
$r1 = 0.0298 * pow($Ps1, -1.016);
// Calculate explosion radius
$r = $r1 * pow($E / [PA:Pa], 1/3);
// Return
return $r;