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Midland Tool

Miller Big Blue® 800 Duo Air Pak™ Welder/Generator with Air Compressor

Item # 907752 Category
  • The most powerful T4F diesel welder/generator/air compressor in the industry
  • Heavy-Duty Low-Speed DEUTZ TD2.9 L4 T4F Industrial Diesel Engine is the cleanest, and greenest diesel power available
  • One dependable engine – two independent arcs with up to 400 amps each (or 800 amps for a single operator). Plug in additional inverter welders for a true multi-operator (3+ arc) work platform
  • Achieve a smoother more consistent arc that can be tailored to match application, material, fit-up, and welder technique with Miller’s proprietary Dynamic DIG
  • Electronic engine display simultaneously displays fuel level, engine hours, coolant temperature, oil pressure, battery volts, air pressure, engine RPMs and engine diagnostics for quick servicing





Field Construction
Maintenance and Repair
Mechanical Contracting
Pipe Fabrication / Construction


Air Carbon Arc Cutting and Gouging (CAC-A)
Compressed Air
Flux Cored (FCAW)
Stick (SMAW)

Weldable Metals

Stainless Steel

Fuel Type


Welding Mode

CC/DC (Stick/TIG)

Output Mode

Paralleled (combined)
Separate (dual outputs)

Separate Output Range

CC/DC (Stick/TIG): 20-400 A
CV/DC (MIG/FCAW): 15 – 50 V

Separate Rated Output

CC/DC (Stick/TIG) 400 A at 36 V (each side)
CV/DC (MIG/FCAW): 400 A at 34 V (each side)

Paralleled Output Range

CC/DC (Stick/TIG): 40-800 A
CV/DC (MIG/FCAW): 15 – 50 V

Paralleled Rated Output

CC/DC (Stick/TIG): 700 A at 44V
800 A at 38 V
CV/DC (MIG/FCAW): 750 A at 40 V
800 A at 38 V

Max Open Circuit Voltage

85 VDC
30 VDC

Gen. Power Rated at 104° F

1-Phase Continuous: 12000 watts
1-Phase Peak: 15000 watts
3-Phase Continuous: 20000 watts
3-Phase Peak: 27000 watts

Air Compressor Model

Ingersoll Rand CE55 G1

Air Compressor Features

Oil change intervals: 500 hours
Rotary Screw with electric clutch for on/off

Free Air Delivery

Idle: 40 cfm (1.13 m³/min)
Weld: 60 cfm (1.70 m³/min)

Working Pressure Constant

100 psig (7 bar)

Air Compressor Duty Cycle


Air Compressor Oil Capacity

4 qt

Auto Compressor Shutdowns

Oil temperature

Engine Model

Deutz TD2.9 L4

Engine Type

EPA Tier 4 Final Compliant
Four cylinder
Includes 120 V block heater
Liquid-cooled industrial diesel


65.7 HP

Weld Speed

1800 RPM

Idle Speed

1350 RPM

Sound Levels at 23 Ft

Idle: 71.3 dB (96.1 Lwa)
Weld (800 A load): 78.9 dB (103.7 Lwa)

Fuel Capacity

25 gal

Oil Capacity

8.5 qt

Standard Shutdowns

High coolant temperature
Low fuel level
Low oil pressure


D: 69.5 in
H (to top of exhaust): 53.5 in
H: 46 in
W: 28.5 in


2095 lbs
Add 165 lbs when tank is full


Optional Trailer Mount