Torch

From GAWDAwiki

A torch is a piece of equipment in which oxygen and fuel gas are mixed and delivered to a nozzle.^[1] It consists of a valve and connection for oxygen, a valve and connection for fuel gas, a handle, a mixing chamber and a tip. ^[2]

A U.S. Marine Corps engineer uses a welding torch.

Torch Components

Oxygen and Fuel Gas Valves

These valves control the flow of oxygen and fuel gas through tubes to the tip of the torch. Gas flows may be adjusted to regulate the size and heat of the flame.

Handle

The handle allows for operator manipulation of the torch to achieve desired results. It also provides housing for tubes en route to the mixing chamber and tip.^[3]

Mixing Chamber

The mixing chamber is the component of a torch in which oxygen and fuel are mixed and combustion occurs.^[4] There are two basic mixer types: the equal or medium pressure type (also known as balance- or positive-pressure type) and the injector type. The equal pressure type is most common and is used when fuel gas pressures are above 1 psi. In this type, oxygen and fuel gas enter the torch at almost equal pressures. The injector type is used when fuel gas pressures are below 1 psi. In this type, oxygen at high pressure pulls the fuel gas into the mixing chamber.^[3]

Tip

Mounted on the end of a torch handle, a tip allows the oxygen and fuel gas mixture to feed a flame. Tips are available in a variety of shapes and sizes and are identified by numbers. Larger numbers indicate larger holes in the tips, which allow for thicker metals to be welded or cut. Welding tips feature a single hole, while cutting tips feature one centrally located hole with many smaller holes arranged in a circular pattern around it. The cutting oxygen comes from the center hole, and the preheat flame comes from the holes around it.^[3]

Types of Torches

Injector Torch

An injector torch is a standard oxy-fuel torch, also known as an equal pressure torch, which mixes two gases. A small nozzle within the torch head releases high-pressure oxygen, dragging the fuel gas along with it by means of the venturi effect.

Rose-Bud Torch

A rose-bud torch heats metals for purposes such as straightening and bending. Its name comes from the shape of the flame it creates. Though it is generally used when a large area requires heating, a rosebud torch can also heat small areas like rusted bolts and nuts (though a filler rod would not be used in this scenario).

Welding and cutting torches

Cutting Torch

As its name suggests, a cutting torch is used to cut metal. A cutting torch is similar to a welding torch, with two exceptions.

A cutting torch features either two or three pipes approaching a 90-degree nozzle. In the two-tube model, oxygen and fuel gas mix and flow to the tip in the bottom tube and the cutting oxygen flows to the tip in the top tube. In the three-tube model, oxygen and fuel gas flow to the tip in the bottom tubes and cutting oxygen flows to the tip in the top tube.
A cutting torch features an oxygen-blast trigger.^[3]

Welding Torch

A welding torch consists of one or two pipes approaching the nozzle, along with valves and connectors for oxygen and fuel gases. Oxygen-blast triggers are absent on welding torches.^[2]