Tweco 190 MIG Thermal Arc Fabricator - Manual (Page 26)

FABRICATOR 190 WELDING MACHINE
INSTALLATION 3-4 Manual No. 0-4838
3.07 Installation of Shielding Gas
(GMAW) Process
Refer to Figure 3-2.
NOTE
Shielding Gas is not required if the unit is used
self shielded FCAW (flux cored arc welding) wires
Cylinder positioning
Chain the cylinder to a wall or other support to prevent the
cylinder from falling over. If an optional portable mounting
is used, follow the instructions provided with it.
Cracking
Remove the large metal cap on top of the cylinder by
rotating counter clockwise. 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. (Fig 3-2.)
CAUTION
Never “crack” a fuel gas cylinder valve near
other welding works, sparks or open flames.
Ensure surrounding area is well ventilated
Regulators – fitting to cylinders
Screw the regulator into the appropriate cylinder. 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.
Regulators – fitting to welder.
Blow out the hose before connecting to the regulator and
rear of welding power source – to remove dust, talc, etc.
The nut on the hose connection is right hand (RH)
threaded and needs to be turned in a clockwise direction
in order to tighten.
Adjusting Regulator
Adjust control knob of regulator to the required flow rate,
indicated on gauge dial. (Refer to Figure 3-1 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
he 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 3-1: Adjusting Flow Rate
Refer to section 4.10 for suggested gas / filler metal
combinations.
NOTE
The regulator/flow meters 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.