Английский для сварщиков. Гричин С.В. - 71 стр.

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71
Mapp Gas
MAPP (methylacetylene-propadiene) is an all-purpose industrial fuel
having the high-flame temperature of acetylene but has the handling
characteristics of propane. Being a liquid, MAPP is sold by the pound, rather
than by the cubic foot, as with acetylene. One cylinder containing 70 pounds
of MAPP gas can accomplish the work of more than six and one-half 225-
cubic-foot acetylene cylinders; therefore, 70 pounds of MAPP gas is equal to
1,500 cubic feet of acetylene.
Cylinder Design
Total weight for a MAPP cylinder, which has the same physical size as
a 225-cubic-foot acetylene cylinder, is 120 pounds (70 pounds which is
MAPP gas). MAPP cylinders contain only liquid fuel. There is no cylinder
packing or acetone to impair fuel withdrawal; therefore, the entire contents of
a MAPP cylinder can be used. For heavy-use situations, a MAPP cylinder
delivers more than twice as much gas as an acetylene cylinder for the same
time period.
MAPP Characteristics
Because of its superior heat transfer characteristics, MAPP produces a
flame temperature of 5300°F when burned with oxygen. MAPP equals, or
exceeds, the performance of acetylene for cutting, heating, and brazing.
MAPP is not sensitive to shock and is nonflammable in the absence of
oxygen. There is no chance of an explosion if a cylinder is bumped, jarred, or
dropped. You can store or transport the cylinders in any position with no
danger of forming an explosive gas pocket. The characteristic odor, while
harmless, gives warnings of fuel leaks in the equipment long before a
dangerous condition can occur. MAPP gas is not restricted to a maximum
working pressure of 15 psig, as is acetylene. In jobs requiring higher
pressures and gas flows, MAPP can be used safely at the full-cylinder
pressure of 95 psig at 70°F. Because of this, MAPP is an excellent gas for
underwater work.
Bulk MAPP Gas
Bulk MAPP gas facilities, similar to liquid oxygen stations, are
installed at some activities where large supplies of the gas are used. In bulk
installations, MAPP gas is delivered through a piping system directly to the
user points. Maximum pressure is controlled centrally for efficiency and
economy. Cylinder-filling facilities are also available from bulk installations
that allow users to fill their cylinders on site. Filling a 70-pound MAPP
cylinder takes one man about 1 minute and is essentially like pumping water
from a large tank to a smaller one.
MAPP Gas Safety

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