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Sensor detects problems in grain storage

One of the favorite products picked by Farm Progress editors at fall farm shows was GSI’s Binspector. Experts say it could revolutionize grain monitoring in storage.

Sensor detects problems in grain storage


One of the favorite products picked by Farm Progress editors at fall farm shows was GSI’s Binspector. Experts say it could revolutionize grain monitoring in storage.

The concept is simple. Turning it into a workable solution has taken nearly a decade. It’s based on picking up changes in carbon dioxide levels above the grain mass. Some earlier articles mistakenly said it measured carbon monoxide.

Key Points

• A spike in carbon dioxide above grain in a bin signals trouble.

• A concept for detecting spikes went from invention to product.

• Farmers across the Corn Belt are testing the unit.


“Every living thing that would grow in a grain bin gives off carbon dioxide,” says Gary Woodruff of GSI. “That includes fungi, molds and insects. If something emits carbon dioxide, a very sensitive carbon dioxide sensor picks it up and electronically alerts someone.”

Early history

Gary Fromme from BinTech, the company that came up with the original concept; Dirk Maier, then a professor of ag engineering at Purdue University and now at Kansas State University; and Klein Ileleji, a Purdue professor, first detected grain spoilage by sensing carbon dioxide levels coming out of the fan in a negative pressure aeration system.

Richard Stroshine, a Purdue grain quality specialist, says they also could sense increased levels coming off a large outdoor pile of corn and in the headspace of a 400,000-bushel bin.

“The increase typically indicates mold activity,” Stroshine explains. Sensing changes in the headspace above the grain proved most successful.

Ready for inventor

BinTech developed a patent-pending, accurate carbon dioxide sensor system based off earlier investigative work. It’s packaged inside a very durable, dust-protected unit.

GSI came aboard to help prepare to market the new product.

“Being able to protect the unit from dust is key,” Woodruff says. “The sensor, ready for market, is so sensitive it can pick up extremely low levels of carbon

Marketing stage

So at this point, the concept and the prototype can detect changes inside a bin much faster than existing technology. Temperature cables have limitations.

“Grain is a good insulator,” Stroshine says. “There may only be a slight increase in temperature five to 10 feet from the hot spot.

“Our job is to market this groundbreaking product,” Woodruff says. It’s still technically in the pre-commercial stage. The entire process, from concept to initial marketing, has taken 10 years.

Twenty Binspectors were in bins during the past two storage seasons, Woodruff says. “So far, everyone who has tried them has had excellent results. They’re being tested on large farms, plus commercial and food-grade sites, in both Indiana and Kansas.”

Note that this version is not yet rated for Class II, Division I hazardous locations, Woodruff says. That’s primarily commercial elevators.

A limited number of units are available today through select GSI dealers. Next spring the product should be ready for a wider-scale launch, Woodruff says. It comes with a solar panel mounted on the grain bin roof that powers the unit so there is no wiring, other than to the sensor inside the bin. All data is sent via cell modem to a central server, and is available via a password-protected website in easy-to-understand terms.

“Once installed, you just move the sensor to the proper location,” Woodruff says. The unit needs to be placed either a foot above the grain if grain is peaked above the eave, or a foot below the eave. Carbon dioxide accumulates inside the bin cylinder up in the peaked grain, and then leaves the pile and flows through the eaves. Corn itself gives off a certain amount of carbon dioxide accounted for as background noise.

Future use

“The beauty is that the sensor can pick up a potential problem early,” Woodruff says. It can send a text, e-mail or phone-call alert to preset addresses and numbers.

For a problem caught early, five to seven days of aeration may correct it, avoiding significant loss.

The official list price is $10,500, but a farmer will be able to install one for less.

“It may not pencil out in older 8,000- to 10,000-bushel bins,” Woodruff says. “But for 25,000- to 100,000-bushel bins or bigger, it could be very economical.”

Spoilage detection: concept to reality

Here’s how this idea progressed.

• Proof of concept — Does it work? (university paper published circa 2000)

• Phase 1 — Refine format and usages. (university paper published)

• Phase 2 — Test final design. (university paper published)

• Pre-release — Distribution of product is limited. (current phase)

• Full release — Product is available to all dealers. (expected in the spring)

Honey, you want to borrow what?

You may have what you need to check grain temperature among the gadgets in the kitchen. Richard Stroshine says a probe that goes 3 feet into the grain is best. But if you don’t have one, try a bimetallic thermometer used in cooking. Try to get one with a stem at least 5 to 8 inches long.

“You want to stick it into the grain mass as far as you can,” Stroshine says. The top few inches may be cooled by headspace air, so you need to get below that point.

“What you’re trying to tell is if the cooling front has moved through the mass,” he says. “If so, the temperature a foot or so beneath the surface should be the same as the average air temperature when you started the fan.”

Probe multiple places, especially from the center to the walls, to make sure there are no places that have not yet cooled due to airflow restrictions.

Time to ‘cool it’ in the bin

A large amount of corn went into the bin during warm weather this fall. It’s necessary to bring the temperature inside the grain mass down to proper winter storage levels. Some experts already have fielded calls from farmers with bins in trouble.

“Cool it down in a timely manner using aeration,” says Richard Stroshine, a Purdue University grain quality specialist. “We recommend that when the grain temperature is 10 to 15 degrees F warmer than the average air temperature outside, move an aeration front through the bin.”

If it’s a typical 0.1-cubic-foot-per-minute fan on a storage bin, it could take 150 hours. If there’s a higher concentration of fines in the center, it will take longer to move the front through.

Stroshine estimates it likely will take three aeration cycles to drop grain temperature down just above freezing.

Don’t forget to cover the aeration fan inlets when not in use, he adds. And if you’re not checking grain weekly during the fall and twice monthly in the winter, you’re probably not checking it often enough.

Don’t freeze out grain!

Stop aerating before you freeze the grain. That’s Richard Stroshine’s advice.

“We’ve traditionally recommended that you not freeze the grain,” notes the Purdue University grain quality specialist. “If you do, you could get some ice buildup in spots within the grain mass.

“That would cause problems when the ice melts. Besides, if you push warmer air through very cold grain next spring, condensation can form on the surface of grain kernels.”

If aeration doesn’t subsequently remove that water, it could cause spoilage, he concludes.

This article published in the December, 2010 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.

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