MAPP is colorless in both liquid and gas form. The gas has a pronounced acetylene-like or fishy odor at concentrations above 100 ppm, due to the addition of substituted amines as a polymerization inhibitor. Low molecular weight alkynes have strong odors. Mapp Gas is toxic if inhaled at high concentrations. Mapp gas is a mixture of various hydrocarbons, principally, methylacetylene , propadiene and Propane(MAPP). It produces a relatively hot flame (2,976°C) with a high heat release in the primary lame (inner cone) (15,445kJ/m 3 ), less than for acetylene (18,890kJm 3 ) but much higher than for propane (10,433kJm 3 ). The secondary flame (outer cone) also gives off a high heat release, similar to propane and natural gas. The combination of a lower flame temperature, more distributed heat source and larger gas flows compared with acetylene results in a substantially slower pierce time.