"gas MAPP" is the trademark name, belonging to The Linde Group, and formerly belongs to Dow Chemical Company, for fuel gas based on a stable mixture of methylacetylene (propyne) and propadiene. The name comes from the original chemical composition, m ethyl a cetylene- p ropadiene p ropane. "MAPP gas" is also widely used as a generic name for the stable methyl acetylene-propadiene UN 1060 (unstabilized methylacetylene-propadiene known as MAPD). MAPP gas is widely regarded as a safer and easier to use acetylene replacement. In early 2008, MAPP gas production actually ended in North America when production was halted at the only remaining plant in North America that still produced it. However, many current products are labeled "MAPP", in fact, a substitute for MAPP . This version is composed almost entirely of propylene with very small propane impurities (& lt; 0.5%).
Video MAPP gas
MAPP gas usage
The original MAPP gas can be used in combination with oxygen for heating, soldering, brazing and even welding due to high flame temperatures of 2925 ° C (5300 ° F) in oxygen. Although acetylene has a higher fire temperature (3160 Â ° C, 5720 Â ° F), MAPP has the advantage of not requiring any special container dilution or filler during transport, allowing larger gas fuel volumes to be transported at the same given weight. , and it's much safer to use.
MAPP/oxygen fire is not fully appropriate for steel welding, because high hydrogen concentrations in flame - higher than acetylene, but lower than other oil fuel gases. Hydrogen sinks into the molten steel and makes the welds brittle. For small-scale welding with MAPP, this is not a serious problem, because hydrogen can get out easily, and MAPP/oxygen can be used to weld small steel parts.
MAPP/oxygen is advantageously used in underwater cutting, which requires high gas pressure (under pressure such as acetylene to polymerize explosively, making it harmful to use). However, oxy/gas fuel cuts of any kind have been replaced by exothermic cuts due to much faster cutting rates and greater security.
The MAPP gas is also used in combustion with air for brazing and soldering, where it has slightly more advantages than competing propane fuels due to its higher combustion temperatures of 2.020 ° C (3.670 ° F) in the air.
The biggest disadvantage of MAPP gas is cost; usually one and a half times more expensive than propane at the refinery, and up to four times more expensive for consumers. No longer widely used in large-scale industries - for users with larger scales, acetylene/oxygen is more economical than MAPP/oxygen when high flame temperatures are required, and propane/air is more economical when the overall heat is needed.
However, for small-scale users MAPP/oxygen fire is still highly desirable, has a fire temperature and higher energy density than fire other than acetylene/oxygen, but without the danger and discomfort of acetylene/oxygen. Jewelry makers, glassbead makers, and many others find it very useful. Plumbers, refrigerators and HVAC engineers and other traders also appreciate the high heat capacity of fire MAPP/air; MAPP to date is widely used, supplied in small to medium sized containers.
Maps MAPP gas
MAPP gas physical properties
MAPP is colorless in both liquid and gas form. The gas has a smell like acetylene or a fishy odor at concentrations above 100 ppm, due to the addition of substituted amines as polymerization inhibitors. Low molecular weight alkynes has a strong odor. MAPP gas is toxic if inhaled at high concentrations.
The composition of the gas supplied varies widely, with gas supplied by different repackaging/resellers at a variable time, and the general composition varies over time, but typical compositions for early Dow gas may be: 48% methylacetylene (propyne), propadiene 23 %, propane 27%. For later 30% Dow/Petromont gas propylene, propadiene 14%, propylene 43%, propane 7%, C 4 H 10 (isobutane, butane) 6% may be more typical.
Thermal property
MAPP has an energy content of 2100 BTU/lb (1.357 kWh/kg) while the acetylene energy content is 2500 BTU/lb (1,615 kWh/kg).
Security
People may be exposed to MAPP gas or their successors at work by inhaling gas or skin/eye contact with fluids. Occupational Safety and Health (OSHA) has set legal limits for MAPP gas exposure in the workplace as 1000 ppm (1800 mg/m 3 ) for 8 hours. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1000 ppm (1800 mg/m 3 ) for 8 hours and 1250 ppm (2250 mg/hour). m 3 ) for short-term exposure. At a rate of 3400 ppm, 10% of the lower explosive limit, MAPP gas is immediately hazardous to life and health.
See also
- Gas methylacetylene-propadiene
- Soldiers
- Oxy-fuel welding
- Crooked welding
- Arc Welding
References
Source of the article : Wikipedia
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