Tweco 1000 Cutting Systems - Manual (Page 23)

Manual 0-2710 3-5 INSTALLATION
B. Secondary Gases
NOTE
Refer to Section 2.03, Specifications & Design Fea-
tures, for proper gas pressure and flow rate.
1. Compressed Air Secondary
• Air secondary is normally used when operating with
air plasma and occasionally with nitrogen plasma.
• Improves cut quality on some ferrous materials.
• Inexpensive - reduces operating costs.
2. Carbon Dioxide (CO
2
) Secondary
• CO
2
secondary is used with nitrogen or Ar/H2
plasma.
• Provides good cooling and maximizes torch parts
life.
• Provides good cut quality on ferrous or nonferrous
material.
• May reduce smoke when used with Ar/H2 plasma.
NOTE
When CO
2
is used as the secondary gas, twenty (50
lb) cylinders must be manifolded together or a bulk
CO
2
system used to get the required flow rate of
200 scfh. Shop compressed air is a good alternative
if providing the required CO
2
flow rate is not fea-
sible.
3. Nitrogen (N2) Secondary
• Nitrogen secondary is used with Ar/H2 plasma.
• Provides smooth finishes on nonferrous materials.
• May be used with nitrogen plasma in order to oper-
ate from one compressed gas cylinder - but torch
parts life may be shorter than with CO
2
secondary.
• May reduce smoke when used with Ar/H2 plasma.
4. Water Secondary
• Water secondary should be used only in mechanized
applications - never in hand cutting!
• Normally used with nitrogen, Ar/H2, or air plasma.
• Provides very smooth cut surface.
• Reduces smoke and heat input to the workpiece.
• Effective up to 1/2 inch (12.7 mm) maximum mate-
rial thickness.
• Tap water provides low operating expense.
3.07 Gas Connection
A. Connection
Connect the gases to the Plasma Power Supply as
described in the Power Supply Operating Manual
(0-2708) supplied with the Power Supply.
CAUTION
Air supply must be free of oil, moisture, and other
contaminants. Excessive oil and moisture may
cause double-arcing, rapid tip wear, or even com-
plete torch failure. Contaminants may cause poor
cutting performance and rapid electrode wear.
B. Checking Air Quality
To test the quality of air, place a welding filter lens in
front of the torch and turn on the gas. Any oil or
moisture in the air will be visible on the lens. Do not
initiate an arc!
C. Filtering
An in-line pneumatic dryer/evaporator type air filter,
capable of filtering to at least 5 microns, is required
when using air from a compressor. This type filter
will insure that moisture, oil, dirt, chips, rust particles,
and other contaminants from the supply hose do not
enter the torch. For highly automated applications, a
refrigerated drier may be used.
NOTE
Do not use an air line filter with high pressure gas
cylinders.