Explosives Safety - Net Explosives Weight (NEW)

Net Explosives Weight (NEW)

The net explosives weight (NEW) is based on explosives compounds that are equal to one pound of trinitrotoluene (TNT). A compound may weigh two pounds but have the blast effects of only one pound of TNT it is then said to have a NEW of one pound. If the compound weights one pound but has the blast effects of two pounds of TNT the NEW is considered as two pounds NEW. NEW is used to calculate QD by means of a formula of the type D (ft) = K•W^1/3, where “D” is the distance in feet, “K” is a factor (also called K-factor) that is dependent upon the risk assumed or permitted, and “W” is the NEW in pounds. When metric units are used, the symbol “Q” denotes Net Explosive Quantity (NEQ) in kilograms. In the formula D (m) = Km•Q^1/3, the distance “D” is expressed in meters. Thus, the units of the K-factor ("K" in the English system) are ft/lb^1/3 and ("Km" in the metric system) m/kg^1/3. The value of “K” in English units is approximately 2.52 times “Km.” For example, if D (m) = 6•Q^1/3, then D (ft) = 15.12•W^1/3. Distance requirements determined by the formula with English units are sometimes expressed by the value of “K,” using the terminology K9, K11, K18, to mean K = 9, K = 11, and K = 18.