Fans fight mold and improve efficiency

Sept. 24, 2012
In this installment of What Works, a warehouse mitigates mold conditions on clean pallets by moving air.

Washing, rinsing, and repeating might be good for your hair, but when it comes to sanitizing wooden pallets, every pallet that has to be washed twice takes extra time. And when the scale is the WestWind Logistics (www.westwindlogistics.net) warehouse in Omaha, Nebraska, filled with 50,000 pallets, that extra time adds up quickly.

The warehouse currently has seven employees and as many as 13 during peek season. Pallets are the only product in the warehouse. “We wash 1,100 to 1,800 pallets a day and can ship as many as 5,000 out per day,” says Plant Manager Vincent Hoy. “Currently, we have 45,000 on hand.

WestWind Logistics is an Iowa-based company founded on quality, commitment and service. Its core competencies include logistic services; new and recycled pallets; wood, paper, and plastic recycling; total pallet management programs; heat treatment for all WPM products; roll-off container services; and pallet sanitation.

Moldy pallets would ruin its reputation.

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WestWind washes wooden pallets and stacks them to dry before they’re put back into service. But any pallet that sprouts mold must be rewashed. Unfortunately, the warm, humid warehouse was the perfect environment for mold, and wood is among mold’s favorite places to set up shop. It was a recipe for disaster.

“If the pallets sit here too long, they mold,” says Hoy. “At one point, we had 4,000 pallets in the warehouse and over half of them got moldy. We have to rewash anything that has mold on it or touching it, so that’s two days of work lost. We needed better air circulation. We were getting a lot of mold on our product.”

Mold spores are ubiquitous in both indoor and outdoor air. Controlling moisture is the key to controlling mold, which is problematic when your storage area shares space with the steam-producing washing equipment. But air movement can help to prevent the establishment of mold by more quickly drying the surfaces on which mold can form.

Mold world conditions
According to Dr. Brian Bond of the Wood Science and Forest Products department at Virginia Polytechnic Institute, optimal conditions for mold growth include wood surfaces with a moisture content of 25% or greater, air temperatures from 66 to 90 °F, and storage areas with little to no air movement. To prevent mold, it is vital to keep the moisture content of the surface of wood 20%. This typically means the average moisture content of the pallet should be in the range of 30-35%. This moisture content must be maintained throughout shipping and storage process.

In May 2011, WestWind looked at several optons, including air handling units and bigger floor fans. But the big warehouse needed big air movement — two 20-ft large diameter, low speed fans, to be exact. The solution came in the form of 24 ft Powerfoil X fans.

“The cost, ease of installation, and being up out of the way made them the right choice,” says Hoy. “Two fans were purchased. They cover 32,000 sq ft. Each fan can handle approximately 6,000 pallets.”

In a hot, humid environment, such as the WestWind Logistics warehouse, the air movement provided by fans prevents the buildup of moisture on surfaces that might harbor mold by continually disturbing the thin sheet of stagnant air surrounding each pallet. By far the most efficient way to move air is with a large diameter, low-speed fan. These fans use their immense size, not speed, to move a massive amount of air using very little energy.

Implementation steps were fairly simple, but electricians had to run power. “We needed to get the fans up as high as possible to stay out of harm’s way because we stack pallets 36 high,” explains Hoy.

The difference at WestWind has been dramatic. Mold growth on drying pallets was reduced by 90%, says Hoy. “About 95% of the stock we put under the fans never molds,” he explains. “The fans move so much air. They do help out immensely. We put everything we wash and sort under the fans. That’s the premium real estate.”

WestWind currently is in negotiations with Big Ass Fans to install additional fans at the facility.

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