Tweco PAK 200i - Manual (Page 44)

PAK 200i
4-6 OPERATION Manual 0-5335
WARNING
AC power is still present inside the unit.
• Fans and pump as well as all indicators turn off.
• The display may show a fault code for a moment, this is a normal part of shutting off power and does not
indicate a fault.
b. Open (turn off) the main power disconnect. All power is now removed from the unit.
• Rear panel AC indicator turns OFF.
Operational Suggestions
1. Wait four minutes before setting the ON/OFF switch to OFF after operation. This allows the cooling fans to run
to dissipate operating heat from the power supply.
2. For maximum parts life, do not operate the pilot arc any longer than necessary.
3. Use care in handling torch leads and protect them from damage.
4.05 Gas Selection
A. Plasma Gases
1. Air Plasma
• Most often used on ferrous or carbon base materials for good quality at faster cutting speeds.
• Air plasma is normally used with air shield.
• Only clean, dry air is recommended for use as plasma gas. Any oil or moisture in the air supply will
substantially reduce torch parts life.
• Provides satisfactory results on nonferrous materials.
�. Argon/Hydrogen (H35) Plasma
• Recommended for use on 3/4 in (19 mm) and thicker stainless steel. Recommended for 1/2 inch (12 mm)
and thicker nonferrous materials. Ar/H� is not normally used for thinner nonferrous materials because
less expensive gases can achieve similar cut quality.
• Poor cut quality on ferrous materials.
• Provides faster cutting speeds and high cut quality on thicker materials to offset the higher cost.
• A 65% argon / 35% hydrogen mixture should be used.
3. Nitrogen (N�) Plasma
• Provides better cut quality on nonferrous materials such as stainless steel and aluminum.
• Can be used in place of air plasma with air shield.
• A good clean welding grade nitrogen should be used.
B. Shield Gases
1. Compressed Air Shield
• Air shield is normally used when operating with air or oxygen plasma.
• Improves cut quality on some ferrous materials.
• Inexpensive - reduces operating costs.
�. Nitrogen (N�) Shield
• Nitrogen shield is used with nitrogen (N2) or Ar/H2 (H35) plasma.
• Provides smooth finishes on nonferrous materials.
• May reduce smoke when used with Ar/H2 plasma.