ВУЗ:
Составители:
Рубрика:
65
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.
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.
Speaking
18 Discuss in the group advantages and disadvantages of using Acetylene
and map gas. Say which gas you would prefer to use for gas welding and
why.
Reading 4
19 Skim the two texts Regulators and Cutting Torches and write
annotations.
Fig. 5 Compressed gas
cylinders containing
oxygen oxygen and MAPP
gas
Страницы
- « первая
- ‹ предыдущая
- …
- 63
- 64
- 65
- 66
- 67
- …
- следующая ›
- последняя »
