Editing MAPP gas (section)

==Use==
Genuine MAPP gas can be used in combination with [[oxygen]] for heating, [[soldering]], [[brazing]] and even [[welding]] because of its high [[adiabatic flame temperature|flame temperature]] of 2925&nbsp;°C (5300&nbsp;°F) in oxygen. Although acetylene has a higher flame temperature  (3160&nbsp;°C, 5720&nbsp;°F), MAPP has the advantage that it requires neither dilution nor special container fillers during transport, allowing a greater volume of fuel gas to be transported at the same given weight, and it is much safer in use.

A MAPP/oxygen flame is not entirely appropriate for welding [[steel]], due to the high concentration of [[hydrogen]] in the flame – higher than acetylene, but lower than any of the other petroleum fuel gases. The hydrogen infuses into the molten steel and [[hydrogen embrittlement|renders the welds brittle]]. For small-scale welding with MAPP this is not a serious problem, as the hydrogen escapes readily, and MAPP/oxygen can in practice be used for welding small steel parts.

MAPP/oxygen was advantageously used in underwater cutting, which requires high gas pressures (under such pressures acetylene can decompose explosively, making it dangerous to use<ref name="FPGHM">{{cite book|author=National Fire Protection Association|title=Fire Protection Guide to Hazardous Materials|edition=14th|page=49|year=2010}} https://pubchem.ncbi.nlm.nih.gov/compound/Acetylene#section=Decomposition&fullscreen=true {{Webarchive|url=https://web.archive.org/web/20210521232837/https://pubchem.ncbi.nlm.nih.gov/compound/Acetylene#section=Decomposition&fullscreen=true |date=2021-05-21 }}</ref>). However, underwater oxy/fuel gas cutting of any kind has been largely replaced by [[thermal lance|exothermic cutting]]<ref>"Exothermic cutting" uses the heat of burning steel wire to cut metals and even non-metals (e.g., concrete).  Typically, the wire is ignited electrically and combustion is sustained via a flow of compressed oxygen.  See:  ''U.S. Navy Underwater Cutting & Welding Manual'', NAVSEA S0300-BB-MAN-010 (1 June 2002), Chapter 2, especially sections 2.3 (Exothermic electrodes) and 2.4 (Seeler Enterprises LU-001 Exothermic Cutting Tool (Kerie Cable)), pages 53–74 (pages 2–22 to 2–43 of original document).  Available on-line at:  http://www.maritime.org/doc/pdf/cut_weld.pdf {{Webarchive|url=https://web.archive.org/web/20141030033224/http://www.maritime.org/doc/pdf/cut_weld.pdf |date=2014-10-30 }} .</ref> because it cuts more quickly and safely.

MAPP gas is also used in combustion with air for brazing and soldering, where it has a slight advantage over competing [[propane]] fuel because of its higher combustion temperature of 2,020&nbsp;°C (3,670&nbsp;°F) in air.

The biggest disadvantage of MAPP gas is cost; it is typically one-and-a-half times as expensive as propane at the refinery, and up to four times as expensive to the consumer. It is no longer used much in any large-scale industry – for larger scale users acetylene/oxygen is more economic than MAPP/oxygen when high flame temperatures are needed, and propane/air is more economic when big overall heating is needed.

However, for the small-scale user a MAPP/oxygen flame is still highly desirable, having higher flame temperatures and energy densities than any flame other than acetylene/oxygen, but without the dangers and inconveniences of acetylene/oxygen. Jewellers, glassbead makers, and many others find it very useful. Plumbers, refrigeration and HVAC engineers and other tradesmen also value the high heat capacity of the MAPP/air flame; MAPP was until recently widely used, supplied in small to medium size containers.

Blowtorches are used to brown and sear food cooked by low-temperature [[sous-vide]] techniques. Myhrvold recommends in ''[[Modernist Cuisine|Modernist Cuisine: The Art and Science of Cooking]]'' that MAPP gases should be used in preference to cheaper butane or propane as they produce higher temperatures with less risk of giving the food a gas flavour, as can happen with incompletely combusted gas.<ref name="Myhrvold 2011 p. ">{{cite book | last=Myhrvold | first=Nathan | title=Modernist Cuisine: The Art and Science of Cooking|volume=2: Techniques and Equipment | publisher=Cooking Lab | publication-place=Bellevue, Wash | year=2011 | isbn=978-0-9827610-0-7 | oclc=711381030 | page=274}}</ref>