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

Item # 907752

The most powerful T4F diesel welder/generator/air compressor in the industry. The Big Blue 800 Duo Air Pak offers robust output for welding and power generation, and is ideal for dual-operator applications on labor intensive jobsites, or jobsites with limited space.

  • Heavy-Duty Low-Speed DEUTZ TD2.9 L4 T4F Industrial Diesel Engine:  The cleanest, greenest diesel power available. DEUTZ T4F models utilize diesel oxidation catalyst (DOC) technology to keep the air clean with NO exhaust after-treatment maintenance.
  • Multi-Arc Welding: 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!
  • Increased Efficiency:  More arcs and better fuel economy equal increased profits for your business. Estimated savings are 34-percent with a dual-operator unit versus two single-operator units.
  • Air Compressor (Ingersoll Rand):  Ultra-reliable industrial rotary screw air compressor. 30,000-hour life expectancy. Independent on/off control for applications not requiring compressed air — allows for greater fuel savings and longer compressor service intervals.
  • Industrial USB Port:  Quickly upload the latest software and download machine log files to retrieve in-depth information such as diagnostics and machine statistics.
  • Dynamic DIG™:  Unlike conventional DIG that provides a preset amount of short-clearing current, Miller’s proprietary Dynamic DIG works on a time-based algorithm that automatically adjusts the amount of current required to clear a short. What does this mean? A smoother more consistent arc that can be tailored to match application, material, fit-up, and welder technique.
  • ArcReach® Technology:  Exclusive ArcReach technology uses existing weld cables to communicate process adjustment commands back to the welder generator. With an ArcReach system, amperage & voltage are conveniently located at the operator’s fingertips – not back at the power source.
  • Increased Productivity & Safety:  More arc-on time, and reduced exposure to slip, trip, and fall hazards can be realized using ArcReach because less time is spent going back to the welding power supply to set process and arc amperage or voltage.
  • Electronic Engine Display:  Electronic engine display simultaneously displays fuel level, engine hours, coolant temperature, oil pressure, battery volts, air pressure and engine RPMs. Also tracks oil change intervals and displays engine diagnostics for quick and easy servicing.
  • Other Standard Features:  Output contactor control, automatic idle, thermal overload protection, digital meters with SunVision™ and 120-volt engine block heater.



Field Construction
Maintenance and Repair
Mechanical Contracting
Pipe Fabrication / Construction


Compressed Air
Air Carbon Arc Cutting and Gouging (CAC-A)
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: 12,000 watts
1-Phase Peak: 15,000 watts
3-Phase Continuous: 20,000 watts
3-Phase Peak: 27,000 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

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


65.7 HP

Weld Speed

1,800 rpm

Idle Speed

1,350 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

Low fuel level
High coolant temperature
Low oil pressure


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


2,095 lbs
Add 165 lbs when tank is full


Optional Trailer Mount