low-pressure (or injector-type) torch is shown in figure
Medium-pressure torches are sometimes called
balanced-pressure or equal-pressure types, since the
acetylene and the oxygen pressure are kept equal.
Pressure per square inch may be from 1 to 6 or 8
pounds; ACETYLENE PRESSURE MUST
NEVER BE ALLOWED TO EXCEED 15 PSI. A
typical equal-pressure general-purpose torch is shown
in figure 3-56. The medium-pressure torch is easier to
adjust than the low-pressure torch and, since equal gas
pressures are used for the medium-pressure torch, you
are less likely to get a flashback; the flame is less likely
to catch in or behind the mixing chamber. More details
on flashback are provided later in this chapter.
Welding TIPS and MIXERS are designed in
several ways, depending on the manufacturer. Some
makes of torches have a separate mixing head or mixer
for each size of tip. Other makes have only one mixer
for several tip sizes. Tips come in various types. Some
are one-piece, hard copper tips. Others are two-piece
tips and include an extension tube to make connection
Figure 3-55.Mixing head for a low-pressure torch.
Figure 3-56.Equal-pressure welding torch.