Setting Gun Polarity For Wire Type; Installing Gas Supply - Miller Millermatic 250X Owner's Manual

2-8. Setting Gun Polarity For Wire Type

Wire Drive
Assembly Lead
+
Shown as shipped – Electrode Positive (DCEP): For
solid steel, stainless steel, aluminum, or flux core with
gas wires (GMAW).
Electrode Negative (DCEN): Reverse lead connections
at terminals from that shown above for gasless flux core
wires (FCAW). Drive assembly becomes negative.

2-9. Installing Gas Supply

6
OM-1320 Page 12
Changing Polarity
D
-
Positive Terminal
4
OR
7
5
Tools Needed:
Work Clamp Lead
D
Negative Terminal
1
2
3
Argon Gas
8 9
CO Gas
2
1-1/8, 5/8 in
1 Polarity Changeover Label
Information
Always read and follow manufac-
ture's recommended polarity.
1
3/4, 11/16 in
Ref. 190 821-A
Obtain gas cylinder and chain to
running gear, wall, or other station-
ary support so cylinder cannot fall
and break off valve.
1 Cap
2 Cylinder Valve
Remove cap, stand to side of
valve, and open valve slightly. Gas
flow blows dust and dirt from valve.
Close valve.
3 Cylinder
4 Regulator/Flowmeter
Install so face is vertical.
5 Regulator/Flowmeter Gas
Hose Connection
6 Welding Power Source Gas
1
Hose Connection
Connect customer supplied gas
hose between regulator/flowmeter
gas hose connection, and fitting on
2
rear of welding power source.
7 Flow Adjust
Typical flow rate is 20 cfh (cubic
feet per hour). Check wire man-
3
ufacturer's recommended flow
rate.
8 CO Adapter (Customer Sup-
2
plied)
9 O-Ring (Customer Supplied)
Install adapter with O-ring between
regulator/flowmeter and
cylinder.
Ref. ST-148 265-B / ST-802 028
CO
2