Design Overhaul for Miller Electric's Air Pak

By Walt Moore, Senior Editor | September 28, 2010

The Miller Air Pak—combining a multi-process welder, generator and an air compressor into a single, compact package—has been a popular machine with firms that maintain and repair big equipment. But, recognizing that the design of even good products can be refined, Miller Electric has overhauled the Air Pak concept. The new Big Blue Air Pak, while retaining its predecessor's versatility, also manages to pack considerably more capability into an even smaller space.

For starters, the Big Blue Air Pak uses a 65-hp, turbocharged Deutz 2011 engine, compared to the 40-hp Deutz F4L912 in the predecessor model. And instead of using one of the engine's cylinders as an air compressor, as did the former Air Pak, the new Big Blue model incorporates an Ingersoll-Rand rotary-screw compressor that boosts maximum airflow 20 cfm (to 60 cfm) and maximum pressure 10 psi (to 100 psi). The new compressor, with a switch-controlled electric clutch, produces pressurized air instantly and only on demand, not continuously, as did the engine compressor.

Welding capability has been increased as well. The new Air Pak has an output range of 20 to 750 amps, and a continuous-duty rating of 500 amps. The former Air Pak's range was 50 to 500 amps, with a continuous-duty rating of 400 amps. The new model also has a greater voltage spread, 14 to 40 volts, compared to the former model's 14 to 36 volts.

From the Big Blue Air Pak's generator, you get 4 kilowatts (kW) of continuous power, versus its predecessor's 3 kW. When not welding, the former Air Pak (as an option) could produce up to 10 kW of single-phase power and 15 kW of three-phase. The new Big Blue Air Pak (Deluxe model) provides 12 kW of single-phase and 20 kW of three-phase power. (The standard Big Blue model provides a DC, CC/CV welding output, while the Deluxe model features an AC/DC polarity switch for AC TIG or Stick welding and a 12/24-volt battery charger/jump starter.)

Through the user's eyes

The benefit of any new design, of course, is best measured by how it better serves the user's needs. To that end, we talked with Ed Minniear, manager of field welding for P&H MinePro Services in Elko, Nev. We also talked with Randy Smith of Norco Welding Supplies, Boise, Idaho, a Miller Electric dealer. Smith sold MinePro its three new Big Blue Air Paks (and also its three previous Air Paks). In on the conversation, too, was Jim Truett, Miller Electric district manager.

High on Minniear's list of Big Blue Air Pak benefits is compressor capability. The new machine produces enough air, he says, to support two technicians when carbon-arc gouging (removing old welds prior to repair.) He can now send out two people to do gouging with just a Big Blue Air Pak and a standard welding machine, no longer needing to also send an auxiliary compressor. The former Air Pak, says Minniear, didn't have quite enough airflow to support two torches, which each need 20-plus cfm.

Plus, says Minniear, the new Air Pak, with 250 added amps at the top of its range, is more efficient at gouging (at which his machines spend 25 percent of their time). That's the result, he says, of the new model's ability to use larger carbon (0.50-inch diameter) and its greater airflow (to blow molten metal from the cut at a faster rate). Increased airflow also allows crews to use larger pneumatic tools, he says, those with up to 1.5-inch drives. And for electric tools, says Minniear, the new Air Pak's increased three-phase power permits the use of larger boring bars and bearing heaters, tools often employed on MinePro work sites.

Although the Big Blue Air Pak has more power than its predecessor at the top of the amperage scale, it also has less at the low end of the scale, 20 amps. This means, says Minniear, that the new model is better at fine TIG welding and small-wire MIG jobs. He's impressed, too, with the new Air Pak's uncommonly smooth arc, unusual, he says, for a large engine-drive machine.

Minniear also thinks the new Air Pak runs more quietly than its predecessor, and he likes the larger fuel tank, which allows multiple days' use. Yet another engine-related benefit, says Norco's Smith, is the machine's electronic ability to reduce welding output in order to keep the engine running at a constant speed. The former model, he says, lugged down the engine when amperage loads were high. This feature, in his opinion, means longer engine life.

Miller Electric's Truett cites another engine benefit, namely, it's certified by the Mine Safety and Health Administration (MSHA)—a big plus for mine owners, he says. And by relieving the engine of air-compressing duties, he says, it operates more efficiently. Plus, the new Air Pak's compressed air is cleaner and drier. The predecessor model needed time to build up air pressure, he says, often prompting users to store air, which caused subsequent condensation problems.

Says Minniear: "The new Air Pak is a machine that can take on anything."