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Shop compressors


There is a 1989 Quincy air compressor operating in Jim Leonard's farm shop in Morgantown, Indiana. Shawn McFarland from Carlinville, Illinois, is still running his Quincy compressor from the 1970s. Winchester, Illinoisan Clair Wilson has a Gardner-Denver pump that came out of a Cuba, Missouri, lead mine circa 1958 that he's still using today. And a vintage 1924 Quincy pump sits in the Air-Mach, Inc., Des Moines, Iowa, showroom. “It's very slow, but it does run and pump,” says Dana Brenneman, sales engineer for the compressed air equipment distributor.

Each man attributes his pump's long life to regular preventive maintenance. “I give it routine oil changes, and I clean the air filter,” says Leonard.

Plus, there is the structural integrity. “I'm a firm believer in a quality pump,” says McFarland, adding that his has been very reliable. “A compressor is one thing you cannot do without in the shop. It goes on when you walk in there.”

Two-stage models

Another thing those machines have in common is that they're all piston-type compressors, as are the five models in the table on the following page. Suitable for most farm shops and many other commercial applications, these two-cylinder (two-stage) models are also oil-lubricated for durability and have 5-hp. to 5.2-hp. motors.

“Piston-type air compressors have the same basic components as an internal combustion engine: a crankshaft, pistons, cylinders, valves, and housing block,” says Hez Salsbury, Pueblo, Colorado, farm mechanic.

“In a two-stage model, the first piston compresses the air and passes it to a second, smaller cylinder that compresses the air further. Oil carryover is usually minimal,” he says. Salsbury also ascribes the endurance of piston-type compressors to their slow running speeds.

Noise level vs. energy use

Duane Myklejord, Fosston, Minnesota, has two Ingersoll Rand models: a single-cylinder and a two-cylinder.

“I do use the two-cylinder (two-stage) model more often. But I have to say I like the single cylinder better – it makes less noise!” he explains. The trade-off is the two-stage model uses less electricity.

Fabrication shop owner and farmer Randy Lackender, Iowa City, Iowa, is satisfied with the two Sanborn compressors he purchased at his local Menards store, one in 2002 and one about three years ago.

“They are cast iron, and they were a good price,” he says. “I use the 60-gallon model for running my plasma cutter, air hoist, and paint sprayer.” He says the airflow in cubic feet per minute is adequate for each piece of equipment.

The five models featured in the table produce from 14.7 cfm to 17.5 cfm.





Better for farm shops

Air-Mach's Brenneman prefers reciprocating piston compressors for farm shops because they have rings that separate the compression process from the oil.

“This separation allows the water, which is squeezed out of the air, to avoid the oil and to pass on into the receiver tank,” he says.

He explains why his company doesn't recommend rotary screw-type compressors for farm shops. “They seal the compression chamber with a small amount of oil injected into the pump. As such, when the air compressor squeezes the air, it does two things. It heats the air, and some of the water vapor is squeezed out in liquid form into the oil,” he says.

“If the air compressor doesn't run long enough to raise the oil temperature to 180°F. to 190°F., the water accumulates in the oil creating an emulsion, which actually robs the pump bearings of lubrication,” he says. “This will prematurely wear out the air end, which is the most expensive part of the compressor.”

He points out that farm shops don't routinely use enough air throughout the day to get the necessary run time on the compressor to adequately heat up the oil and drive the water out. An exception would be the job of blowing off combines and other equipment since air is used continuously for a long period.

Automatic drain valve

He doesn't need a new compressor yet, but Darrell Geisler (pictured above) of Bondurant, Iowa, is looking at them anyway. He understands the potential of high maintenance with a rotary screw model, but he's considering one nonetheless. And he's learned there are ways to manage the water issues.

“I'm looking at a water separator mechanism, which doesn't necessarily come with the compressor. It's electric and automatically dumps the water whenever it deems necessary. But if it's not in a heated area, it won't work properly,” he says.

Bob Wittman's shop is heated, but he says, “We still have to pay attention to periodic draining of the compressor.”

Since the compressor is located remotely from his Lapwai, Idaho, farm shop, there is also a line entering the shop with a drop tube.

“That 10-inch length of tube (which has a quarter-turn valve on the end for easy emptying) provides a little storage for water, too, and it probably gets drained more often than the compressor,” says Wittman.

Convert Continuous Run To Start/Stop

The compressors in the table above all operate with an automatic start/stop function. They cut out when they reach about 175 psi, and crank up again when they're down to around 145 psi.

Doug Martins has a continuous-run model in his shop in Fairbank, Iowa. So he came up with a way to make his unit more energy efficient. He installed an industrial-strength solenoid on the air outlet side of his compressor and wired it into the light switch.

“When the last person out at night flips off the lights, the air supply shuts down,” he says.



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