Stainless Steel
Monday | 01 October, 2012 | 2:42 pm

Curtailing condensation

By Lauren Duensing

Big fans reduce material loss, increase workers’ comfort

September 2012 - When it’s 95 degrees in the warehouse, workers lose approximately 20 percent of their total productivity, according to a 2006 study, “Room temperature and productivity in office work,” by O. Seppänen, W.J. Fisk and Q.H. Lei. Instead of focusing on immediate tasks, employees’ minds are wandering, thinking about how they can cool off, which leads to an increase in unsafe behavior.

“There are a number of different reasons we use fans in customers’ facilities,” says Christian Taber, applications engineer at Big Ass Fans, Lexington, Ky. “Comfort is usually one of the main reasons. These buildings tend to be heating only, so they’re comfortable—or at least somewhat tempered—in the winter. In summer, generally, it is outside air cooling the building, so there is a lack of comfort for employees, which affects productivity,” Taber says. “ The other main reason is localized moisture-related concerns, whether that’s condensation on the floor, mold on boxes caused by condensation, corrosion of materials or lack of integrity of cardboard boxes due to moisture forming on them.”

Sweating material

Condensation is a problem for metal service centers because the material is exposed to significant temperature changes while it sits on the warehouse floor.

“In the fall and spring, you tend to see a big change in temperature from day to night paired with moist air,” Taber says. “At night, the stored material gets cooled down, and during the day, the air temperature rises a lot faster, so you have this really cool item sitting there with this warm, humid air, and condensation occurs. Condensation on metal means corrosion eventually.”

Problems also can occur immediately after delivery, when the cooler metal is brought into a warmer space. During the warm-up period, the metal’s surface temperature is below the dew point, leading to condensation.

In Garland, Texas, the variable temperatures and high humidity created multiple condensation issues at O’Neal Flat Rolled Metals. Phill Cavender, vice president of sales, said the condensation problem started on galvannealed material, and the company had issues with aluminum, as well. In addition, beads of condensation would form on the floor, making it extremely slick and unsafe for employees.

Cavender had seen Big Ass Fans in his customers’ facilities, so he brought out one of the company’s representatives to look at the facility and recommend a solution. “The [20-inch diameter Powerfoil X] fan that we bought is a ceiling-mounted fan that will cover about 30,000 square feet of space. We have about 85,000 square feet that is divided into two bays, so we opted to go with four fans because there wasn’t a good way to center those down the building.

“We run them at the highest speed all the time, 12 months out of the year when nobody is in the building,” Cavender says. “When employees are in the building, one of the fans is directly over a packaging area so we turn that fan down only a little bit when we’re here, but they are running 600 to 650 rpm maximum speed most of the time.”

Increased air movement can solve both condensation and safety issues, bringing the warehouse temperature to a more comfortable level and reducing material sweating. According to literature from Big Ass Fans, by increasing the air speed to 1.2 miles per hour, heat transfer can occur up to 2.5 times faster, providing a faster warm-up time and less chance for condensation and corrosion. If condensation does occur, air movement speeds the evaporation rate.

An airflow solution

Big Ass Fans offers a variety of products to satisfy each customer’s unique airflow requests. “We’ll walk through a customer’s facility and talk to them about where and when their problems are occurring, just to get a better idea of what they’re really trying to address with air movement,” Taber says. “Then we’ll go through our wide array of fans to find the best fit. Ideally, we’d like to use big overhead fans everywhere, but the reality is you can’t always do that due to ceiling heights or obstructions or cords that come down from the ceiling, so we have a variety of options because our customers don’t all have wide open spaces with infinite floor-to-ceiling heights.”

Taber says the company could recommend a lineup of the same fans, different sizes or different spacing. “If a space has narrow aisles, we generally don’t want to use a big fan over a lot of racking. We might use a more directional product down the aisles. If it’s in a loading dock area, we’d probably go with a large overhead fan because we have the width and height to fit that fan in.”

Cavender says the installation of his four Powerfoil X fans was easy. “The fans are out of the way from an operations standpoint; we do everything with the cranes riding below them. There’s no adverse effect on any of our operating areas or any of our equipment.”

Whether it’s improvements in productivity or decreased material loss, payback can be as quick as one or two months, Taber says. “When you’re losing $100,000 or $200,000 worth of product a year, it doesn’t take real long to pay that back. On the other hand, if you’re not losing much material due to condensation, you have to rely on something else, like the reduction in heating energy during the winter or the improved productivity during the summer.”

“We basically went from material loss of $200,000 to $250,000 per year to zero in the first two years we had the fans,” Cavender says, noting the only material loss since installation was the result of a power failure.

“It wasn’t the fans’ fault,” he says. “Between 6 p.m. one evening and 6 a.m. the next morning, we had a power failure, and the fans reset. They don’t turn themselves back on, and we ended up with condensation in that 12-hour period because a storm came through.” This resulted in the company writing off some aluminum product, but, as Cavender points out, “It speaks to the effectiveness of the fans.” MM

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