User Manual

OPERATION 3 - 8 Manual 0-2529

3.4 GAS SELECTION FOR PLASMA CUTTING

• Air plasma is normally used with air secondary.

• Only clean, dry air is recommended for use as plasma

gas. Any oil or moisture in the air supply can substan-

tially reduce torch parts life.

• Most often used on ferrous or carbon base materials to

obtain good cutting quality at faster cutting speeds.

• Provides satisfactory results on non-ferrous materials.

• Can be used in place of air plasma with air secondary or

• Provides much better parts life than air.

• Provides better cut quality on non-ferrous materials such

as stainless steel and aluminum.

• A good clean welding grade nitrogen should be used.

AIR PLASMA

NITROGEN PLASMA

ARGON/HYDROGEN

PLASMA

• A 65% argon/35% hydrogen mixture should be used.

• Recommended for use on thicker (1/2 inch and up) non-

ferrous materials. Ar/H

2 is not normally used for thin-

ner non-ferrous materials because less expensive gases

can achieve similar cut quality.

• Provides faster cutting speeds and high cut quality on

thicker materials to offset a higher cost.

• Poor cut quality on ferrous materials.

OXYGEN

PLASMA

• Oxygen is recommended for cutting ferrous materials.

• Provides faster cutting speeds.

• Provides very smooth finishes and minimizes nitride

build-up on cut surface (nitride build-up can cause

difficulties in producing high quality welds if not re-

moved).

Table 3-A Plasma Gas Selection for Plasma Cutting