Figure 6-28.--Mixing head for injector-type welding torch.
The equal pressure torch (fig. 6-29) is designed to
and the other for adjusting the flow of oxygen. In
operate with equal pressures for the oxygen and
addition, there are two tubes, one for oxygen and the
acetylene. The pressure ranges from 1 to 15 psi. This
other for acetylene; a mixing head; inlet nipples for the
torch has certain advantages over the low-pressure type
attachment of hoses; a tip; and a handle. The tubes and
because the flame can be more readily adjusted, and
handle are made of seamless hard brass, copper-nickel
since equal pressures are used for each gas, the torch is
alloy, stainless steel, or other noncorrosive metals of
less susceptible to flashbacks.
adequate strength.
The welding tips are made of hard, drawn,
There are two types of welding torches--the
electrolytic copper or 95-percent copper and 5-percent
low-pressure or injector type and the equal-pressure
tellurium. They are made in various styles and types,
type. In the low-pressure or injector type (fig. 6-28), the
some having a one-piece tip either with a single orifice
acetylene pressure is less than 1 psi. A jet of
or a number of orifices, and others with two or more tips
high-pressure oxygen is used to produce a suction
attached to one mixing head. The diameters of the tip
effect to draw in the required amount of acetylene. This
orifices differ to control the quantity of heat and the
is accomplished by the design of the mixer in the torch,
type of flame. These tip sizes are designated by
which operates on the injector principle. The welding
numbers that are arranged according to the individual
tips may or may not have separate injectors designed
integrally with each tip.
Figure 6-29.--Equal pressure welding torch.
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