Tweco 15XC CE Merlin PAK - Manual (Page 42)

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
CO 2 .
• 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