Methylacetylene-Propadiene Stabilized (MPS):

MPS is stabilised acetylene, liquefied like fuel that might be stored and handled similarly to liquid propane. MPS is a mixture of various hydrocarbons, by including butadiene propadiene (allene), butane, propane and methylacetylene. Methylacetylene, as acetylene, is an unstable, high- energy, triple-bond compound. The other compounds in MPS dilute the methylacetylene adequately to make the mixture safe for handling. The mixture burns hotter than either propane or natural gas. This also affords a high release of energy in the primary flame cone, another characteristic same to acetylene. The outer flame gives relatively high heat release, as propane and propylene. The total heat distribution in the flame is the most even of any of the gases.

A neutral flame is attained at a ratio of 2.5 parts of torch-supplied oxygen to 1 part MPS. Its maximum flame temperature is attained at a ratio of 3.5 parts of oxygen to 1 part of MPS. These ratios are utilized for the similar applications as the acetylene flame.

Although MPS gas is similar in various characteristics to acetylene, it needs about twice the volume of oxygen per volume of fuel for a neutral preheat flame. Therefore, oxygen cost shall be higher when MPS gas is utilized in place of acetylene for a specific job. To be competitive, the cost of MPS gas should be lower than acetylene for the job.

MPS gas does have a benefit over acetylene for underwater cutting in deep water. Since acetylene outlet pressure is restricted to 207 kPa absolute, this is usually not applicable at depths below 6m of water. MPS might be used there and at greater depths, as hydrogen. For a specific underwater application, acetylene MPS, and hydrogen should be evaluated for preheat fuel.