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  • The compressor quickly separates into two parts for easier carrying.

    Credit: Sim Ayers

    The compressor quickly separates into two parts for easier carrying.
  • The top section can be used solo for powering a finish nailer or other small jobs.

    Credit: Sim Ayers

    The top section can be used solo for powering a finish nailer or other small jobs.

I’ve been a hands-on contractor since 1989, building everything from custom homes to 32,000-square-foot commercial buildings. At the moment, I’m running a four-man crew and doing fire-insurance work. Regardless of the job, we normally use hand-carry, twin-stack compressors for everything from framing to finish. I’ve owned a bunch of them over the years, and they’re usually a good match for the work we do. But they’re bulky and weigh up to almost 80 pounds, which makes them a chore to carry.

Ridgid’s new oil-free Mobil Air Tri-Stack 5-gallon compressor (model OF50150TS) separates into two parts for carrying, and it also delivers more air than my twin-stacks. When I saw it at Home Depot several months ago, I couldn’t resist buying it to see if it would be a significant step up.

Split Personality

As the name indicates, the Tri-Stack has three tanks, including a pair of two-gallon tanks on the bottom and a one-gallon tank up top that bolts to the motor. The bottom has a regulator with two outlets, and the top has a regulator with one outlet.

If you search “tri-stack” at and click on the link, you can view a video that demonstrates the compressor’s versatility. For starters, you can separate the top and bottom units by simply pulling and twisting a knob and releasing the connecting hose. That allows you to carry the 43-pound top section with one hand and the 34-pound bottom section with the other. You can also use the regulated top section solo for powering a finish nailer and other small loads. Used this way, the compressor kicks on after almost every shot because of the small top tank, but for some interior trim jobs, we’ve found the self-contained unit to be a convenient substitute for a pancake. Meanwhile, the bottom unit can serve as a regulated air-carry tank, but according to Ridgid you can only drive about 20 two-inch, 15-gauge finish nails into pine before you have to reconnect the top unit to refill the tanks. For small jobs, why not just use the top unit instead?

Yet another option is to separate the two units and connect them with an extension hose so you can plug the compressor directly into a receptacle (as recommended) but move the main tanks closer to the work. We’ve done this, and although it allows us to use shorter hoses, we haven’t noticed any change in line pressure.

Most of the time, though, we use the compressor conventionally and only break it down for easier carrying.


The Tri-Stack has other premium features, including quarter-turn ball valves for draining the tanks and quick-connect hose couplers. I also like its oil-free convenience.

As a general guideline, Ridgid says the compressor will power two framing nailers. Plugging directly into 20-amp circuits and using a splitter, we’ve simultaneously run up to two framing nailers, a palm nailer, and a metal-connector nailer, which is more than we can do with our twin-stacks. However, we normally use just one nailer at a time when nailing off shear walls with the Tri-Stack. It has a duty-cycle rating of 50%, which means it can pump about half the time you use it without causing excessive wear. I didn’t time it, but I’m pretty sure we generally stayed within that limit. That’s a conservative rating, though; Ridgid actually pushed the compressor to 67.7% in its durability tests.

The Bad News

I had to return my first Tri-Stack after a week because it suddenly only pressurized to 30 psi and kept running. I simply swapped it for a new one. The second one ran great for about six months, then the same thing happened. Call me crazy, but we like the compressor’s easy carry, ample power, and versatility so much that I’m not only having it repaired (luckily there’s an authorized service center about 20 miles away), but I just bought another one. I’m hoping I initially bought into a defective batch or tapped into damaging low voltage on a job site, but we’ll see.

Sim Ayers owns SBE Builders in Discovery Bay, Calif.