Tweco 281 Thermal Arc Fabricator - Manual (Page 28)

FABRICATOR 281
3-6 April 10, 2006
3.07 Installation of Shielding Gas
(GMAW) Process
NOTE
Shielding Gas is not required if the unit is used
with self shielded FCAW (flux cored arc
welding) wires
1. Cylinder positioning: Block the wheels of the unit
so it cannot roll. Carefully stand the cylinder on the
tray and with one foot press against the bottom of
the cylinder to assure it is against the back of the
unit. Chain the cylinder in place. (Refer to Figure 3-5
#1 for Wheel Kit cylinder installation)
2. Cracking: Remove the large metal cap on top of the
cylinder by rotating counter clockwise (Figure 3-5 #2).
Next remove the dust seal. Position yourself so the
valve is pointed away from you and quickly open and
close the valve for a burst of gas. This is called
“Cracking” and is done to blow out any foreign matter
that may be lodged in the fitting. (Figure 3-5 # 3.)
3. Fit Regulator/Flowmeter to cylinders:
Screw the regulator into the appropriate cylinder.
(Figure 3-5 #4) The nuts on the regulator and hose
connections are right hand (RH) threaded and need
to be turned in a clockwise direction in order to tighten.
Tighten with a wrench.
CAUTION
Match regulator to cylinder. NEVER CONNECT
a regulator designed for a particular gas or
gases to a cylinder containing any other gas.
4. Attach supplied gas line: Attach supplied gas line
between the regulator output and the desired input
at the rear of the power supply depending on Spool
Gun or MIG Gun use. (Refer to Figure 3-5 #5 and
3-14).
Adjusting Regulator
Adjust control knob of regulator to the required flow rate,
indicated on gauge dial. (Refer to Figure 3-4 and data
charts Approx. 20 CFH)
The gas flow rate should be adequate to cover the weld
zone to stop weld porosity. Excessive gas flow rates may
cause turbulence and weld porosity.
Argon or argon based gas flow rates:
- Workshop welding: 20-30 CFH
- Outdoors welding: 30-40 CFH
Helium based or CO2 gas flow rates:
- Workshop welding: 30-40 CFH
- Outdoors welding: 40-50 CFH
NOTE
All valves downstream of the regulator must
be opened to obtain a true flow rate reading
on the outlet gauge. (Welding power source
must be triggered) Close the valves after the
pressure has been set.
Art # A-07280
Figure 3-4: Adjusting flow rate
Refer to section 5.03 for suggested gas / filler metal
combinations.
NOTE
The regulator/flowmeters used with argon
based and carbon dioxide shielding gases are
different. The regulator/flow meter supplied is
for argon based shielding gases. If carbon
dioxide is to be used a suitable carbon dioxide
regulator/flow meter will need to be fitted.