July/August 2004
Tire recycling operations face fire risks, but these can be minimized or eliminated through smart operational practices, employee training, and advance planning.
By Jim Fowler
Max Daughtrey will always remember when he got the call on his cell phone.
Daughtrey, vice president of operations for Four D Corp. (Duncan, Okla.), was sitting in the stands at a University of Oklahoma football game in Norman, Okla. His plant manager called with the news that there was a fire in the firm’s tire recycling plant, and he urged Daughtrey to come quickly. Before he could drive far, his phone rang again—“Max, hurry up, it’s getting worse.” By the time he got out of Norman, the phone rang for the third time—“Max, slow down, there’s no use getting here in a hurry ’cause it’s all gone.”
Later, Daughtrey learned that a spark from his company’s tire processing machinery had entered the baghouse where the tire fiber is collected. The baghouse caught fire, then some rubber under the baghouse flamed up.
When the fire department arrived, the firemen “tried to put the fire out with some foam,” Daughtrey recalls. “Then, in their great wisdom, they hooked up their high-pressure hose to scatter the small pieces of ground-up rubber.”
Unfortunately, right behind the burning rubber was a door leading to the firm’s fiber separation system. “The firemen blew the fire right under the separation system, and the rest is history—a $2.5-to-$3-million history lesson,” Daughtrey says.
Understanding the Problem
As Max Daughtrey can attest, fire can have devastating effects in tire recycling operations. In general, tire shredding operations—which encompass the majority of facilities—have low fire risks. That’s because the shredding equipment operates at slow speeds and, thus, doesn’t create sparks or generate excessive heat during processing. Bill Vincent, CEO of tire shredder Colt Inc. (Scott, La.), says he has “never heard of a fire in a tire shredder,” though he concedes “it’s not beyond the realm of possibility.”
Tire recyclers who operate grinders and granulators to produce crumb rubber and rubber powders face greater fire risks. In these plants, shredded material is fed into a medium-speed grinder that reduces the shreds to 3/4-inch chips. At this second processing stage, the majority of tire steel is being liberated from the rubber. Sparks can be generated as the grinder’s blades contact the tire steel, and these sparks can ignite a fire.
“In our experience, this is the most volatile stage of the process,” says Mike Hinsey, operations managers for Granutech-Saturn Systems Corp. (Grand Prairie, Texas), an equipment manufacturer. “Rubber will get hotter here than anywhere else in the line.”
If the machinery is processing passenger tires, there’s yet another consideration—fiber inside the tires that’s liberated during granulation. “When you’re grinding up rubber and steel, you get fiber and sparks,” says Max Daughtrey. “Fiber that comes out of tires is extremely flammable—about like gasoline.” (To avoid this problem, some firms process only truck radial tires, which generate minimal fiber.)
Despite these potentially incendiary conditions, fires are not inevitable. Tire recyclers can prevent fires in their facilities through best operational practices, employee training, and advance planning.
Maintenance and Housekeeping
Tire recyclers cite maintenance and housekeeping as the two most important aspects of preventing fires in and around processing equipment.
According to Mike Hinsey, more than 75 percent of the fires in tire processing machines can be attributed to poor maintenance or poor housekeeping. “You can’t operate a crumb rubber plant and not have a daily maintenance and cleaning process,” he states. “You’re dealing with combustible materials and running them in machinery that’s going to generate sparks. No matter how effective someone’s dust collection system is, no matter how airtight the material handling equipment is, dust and powder are going to be generated and you simply can’t let it get out of hand.”
Rubber dust is indeed volatile, reportedly requiring a minimum concentration of only 30 grams per cubic meter to explode. This emphasizes the need for tire recyclers to keep their plants clean and prevent rubber dust from accumulating.
Troy Hess, vice president of Mahantango Enterprises Inc. (Liverpool, Pa.), is one tire processor who can’t stress cleanliness enough. “You absolutely need to keep a clean operation,” he says. At his company, the processing facility is cleaned every night after each eight-to-10-hour shift, with each employee covering a specific area, from blowing off the motors to sweeping and blowing the floor, Hess notes.
Another processor—Derek Martin, president of High Tread International Ltd. (Lockport, N.Y.)—says housekeeping is particularly critical on units that remove tire steel, which present the greatest fire potential. “If they’re not properly maintained, both in routine maintenance and while they’re operating, you’re running a risk,” he asserts. “You should clean them out every couple of hours and not allow anything to build up. If that’s not done properly, in effect, you create a fire.”
Operators should also prevent dust from collecting in the ceiling rafters and/or beams of their plants, advises Rick Colyar, national sales manager for equipment producer Columbus McKinnon Corp. (Sarasota, Fla.). To eliminate that problem, Troy Hess welded shields on the I-beams in his ceiling so there are no exposed ledges to hold dust.
Spark Detection and Suppression
Due to the risk of fire, most operators agree that granulation lines today require spark detection and suppression systems. “It’s not an option,” Hinsey asserts. “In our opinion, it’s absolutely mandatory.”
As Colyar explains, “To remove the wire from the rubber, you’re going to have sparking inside the machine, so the real issue becomes containment. That’s what a spark detection and suppression system can do.”
One vendor in this niche is Flamex Inc. (Greensboro, N.C.), which offers a high-speed infrared detection and suppression system. Among its features, the Flamex system has a flame detector on the outfeed of the processing system. “An infrared flame detector is used to stop the belt from moving down the process line and trigger a water spray in the machine as well as the infeed and outfeed to extinguish any fire,” notes Allen Wagoner, the firm’s vice president.
The Flamex system also has spark detectors in the ductwork of the processing system. These detectors “trigger a water suppression valve and nozzle downstream to quench any burning material coming through a duct,” Wagoner says. “The key is to keep the spark or fire from getting into the baghouse.”
Flamex has expanded its system for crumb rubber processing plants to include a manual release station that enables the operator to shut the machine down if he sees a problem before it is recognized by the flame detectors. While the spark detection inside ductwork is extremely fast, Wagoner explains, flame detectors in open-air applications take longer to recognize and distinguish a fire from other light sources.
Plant Considerations
Proper facility design, layout, and construction are other important factors in preventing tire recycling fires. In Mike Hinsey’s view, too many processors shoehorn their processing system into a plant that’s too small. “What they should do,” he says, “is keep their equipment spread out,” which makes their operations safer and maintenance easier.
When operators don’t have adequate space, they tie their processing systems together, notes Jana Nairn of Golden By-Products Inc. (Ballico, Calif.). This can put the second processing stage—the “sparky” stage—right in the middle of the operation. If a fire breaks out in this section, it can affect all other parts of the processing system as well as the plant as a whole.
To combat this situation, Golden By-Products has isolated its “hot spot,” Nairn says, noting that “there’s nothing adjacent to or adjoining it. When you’ve got a granulator, you need to keep ‘sparky’ away from the rest of the operation.”
Another critical consideration in plant layout is how the ductwork is configured to the baghouse, says Dave Quarterson, senior director of Liberty Tire Services Inc. (Pittsburgh). “If a spark ignites the fluff in the ductwork and you don’t have it configured right, the spark gets sucked into the baghouse and now you’ve got your entire baghouse going up in flames,” he points out.
So, how to configure your ductwork correctly? Offering one view, Flamex’s Allen Wagoner says that with pneumatic ductwork you need sufficient length to allow the fire-prevention system to detect and suppress the spark in the duct. “That distance is mandated by the air velocity,” he says, noting that his firm likes to have “a good 30 feet of ductwork between the pickup point of the dust before it goes into the baghouse.”
Some tire recyclers have reduced their fire risks by using flexible polypropylene tubing coiled with wire between their second-stage grinder and its ductwork as well as the fiber handling system and its ductwork. This flex tubing, which extends 6 to 8 feet, has a flashpoint of 160 degrees F. If there’s a fire and the detection/suppression system fails to shut a machine down, the tube will melt away, preventing the fire from traveling beyond the machine into the ductwork.
Other plant layout and construction suggestions include building tire recycling facilities out of “only steel and concrete,” says Derek Martin. Echoing that point, Troy Hess notes that his building has walls made of 10-inch-thick concrete. Also, his two processing rooms and one large maintenance room are sealed from each other, with three fire doors enabling the company to contain a fire in one area.
Hess has also installed all of the plant’s electrical controls in a separate room. Why? Because “motor starters create static, and tire fiber is an intense fuel source,” he explains. “Having them separated in a clean space has been a huge improvement.”
After fire destroyed his plant, Max Daughtrey rebuilt it with one side open. “Our previous building was totally enclosed,” he says, “so when the fire got inside, it was dark with nothing but black smoke. The firemen wouldn’t go in and fight it except from the doorways.” Thanks to his plant redesign, he says, “If we ever have another fire, the firefighters can roll right in.”
Smart and Proper Storage
Tire processors must also know certain best practices—as well as government rules—about how to safely and properly store whole as well as well processed tires, both indoors and outdoors.
Norman Emanuel, president of Emanuel Tire Co. (Baltimore), recommends keeping whole tires in the trailers in which they arrive until you’re ready to process them. This is the safest and cheapest storage approach, he says, since the tires are contained and you don’t have the added expense of multiple handling.
When it comes to processed material, states often have rules that dictate how much material can be stored and in what configuration. “The configuration of storage piles is the critical point,” Dave Quarterson says. In Ohio, for instance, “you have to put the piles of 3-to-5-inch chips in defined wind rows that can measure no more than 50 feet wide, 15 feet high, and 150 feet long. Each row must be separated from the next wind row by at least 50 feet. The purpose is to prevent fire from migrating from one wind row to another. With the pile being only 15 feet high, if there is a fire, you can get in and cut it out.”
Processors who grind rubber to 3/4-inch pieces should know that the rubber will heat up to 200+ degrees in the summer, Max Daughtrey notes. “If you put that rubber in a contained box and let it sit, within eight hours you’ll have a fire,” he says. “If you let chips that are 200 to 225 degrees sit for six or seven hours without air movement through them, they will auto-ignite.”
Daughtrey knows this from hard personal experience. Nearly 10 years ago, he was trying an experimental machine that processed tire rubber to 3/4 inch and liberated most of the steel. A customer wanted to see the final product so he asked Daughtrey to ship two Gaylord boxes of the material to Chicago. Daughtrey filled the two boxes with material right out of the machine, then sealed the boxes with tape. The next morning the freight company that had picked up the boxes called and asked what was in them. Daughtrey replied that the boxes were filled with rubber. The shipping firm told him that when they had opened the back of the truck and oxygen poured in, the Gaylord boxes ignited, burning up a whole shipment of Tupperware. “We didn’t realize back then how dangerous it was,” says Daughtrey.
Offering additional advice, Bill Vincent notes that processors who make a small product must watch how they store the resulting residual material. “Granulators make a lot of residue,” he says, describing this material as a large amount of wire and a small amount of rubber. “If you get it piled up in one place, it’s been known to cause a heating problem. If it sits there long enough, it finally catches fire. It’s a situation you need to be aware of.”
Safety Procedures and Training
Derek Martin speaks for many tire recyclers when he says, “We live in fear of fires,” but that fear can be lessened by training employees how to prevent fires as well as how to respond effectively if a fire breaks out. “There’s no substitute for having your employees trained to react rather than just run for their lives,” states Dave Quarterson.
Training must first instruct employees how to operate the processing equipment so as to prevent a fire from developing. High Tread International, for instance, has procedures that “guide employees on such things as how long you can safely run a machine before you need to stop it and pull the screens as a precautionary move and when you need to clean your screens to prevent a buildup,” says Derek Martin. “If you’re not aware of that buildup, it’s your first path to disaster.”
Training must also include emergency response procedures so employees have ingrained knowledge of what to do if a fire develops. “We would use our equipment to tear a pile down and smother it immediately with dirt,” Jana Nairn notes. “We also have two fire trucks on-site with a large volume of water available and a drain system to contain all the water on our property so there’s no chance of water or oil runoff.”
In particular, training can help ensure that employees don’t act in a way that endangers themselves or makes the situation worse. When there’s a fire, notes Derek Martin, “the operator’s instinct tells him to shut the machine down, which isn’t necessarily the right thing to do. He’s better off shutting down the infeeds, outfeeds, and dust collection. You want to contain, control, and then fight the fire to get it out.”
It’s also essential for employees—as well as owners, in many cases—to acknowledge that “production is not more important than fire prevention,” says Troy Hess. For instance, “if there’s a machine breakdown, preparing the area and taking more time to fix it properly to prevent a fire has to be on the minds of your maintenance people.”
Working With the Fire Department
An important but often overlooked part of advance planning is establishing a relationship with the local fire department.
One way to do this is to invite firefighters to tour your operations. Jana Nairn, for instance, has had local firefighters tour Golden By-Products many times. As a result, she’s confident they would know what to do if the plant had a fire. Likewise, when Dave Quarterson was working in Florida, the local fire department “brought a large group of firemen and toured the entire 30-acre facility to be aware of the layout and access.”
During such tours, draw from the firefighters’ knowledge, asking them for pointers and assistance. “When it comes to fire safety,” Quarterson says, “your fire department is a real untapped resource.” His company even retained a fireman from an adjoining county to visit its plant twice a year and identify problem areas.
In a related vein, Troy Hess has a volunteer firefighter as an employee. This staffer “does routine inspections, puts on training programs for the other employees, and coordinates with the local fire departments about what we’re doing and what they would need to do here,” he says.
By working with your fire department, you can educate each other and help prevent problems down the road. As Norman Emanuel points out, “Fire-men always want to put water on burning rubber. In certain circumstances, water is the worst thing you can use.” If you’ve got tire chips on fire, for instance, the best move can be to smother them with chips that are two or three months old because such chips “are harder to burn,” he explains. Conveying that kind of specialized knowledge to the local firefighters can improve their response.
In the plant fire at Four D Corp. noted at the start of this article, the fire department should have let the original fire burn in place, says Max Daughtrey. “We’d have lost a baghouse on the outside of the building and some rubber out there,” he states. “Instead, they decided to knock it down, but they knocked it right inside. They never acknowledged that they’d done it wrong.”
Getting to know your local firefighters in advance can help prevent such missteps from occurring.
In the end, “there isn’t a one-step process to stop fires,” notes Troy Hess. To him, the most important point is to “control the fuel source—from having a clean shop to having your piles managed and away from your facility.” As Michael Blumenthal of the Rubber Manufacturers Association (Washington, D.C.), adds, “Preventing fires in scrap tire processing plants is a matter of management and money. There’s no single cause for fires—a series of factors are involved. The better you manage these factors, the less likely you are to have a fire. If one should occur, good management will tend to reduce the fire’s severity. The key is to manage the entire system, not just one aspect of it—it’s a complete package.”
Jim Fowler is retired publisher and editorial director of Scrap.
Tire recycling operations face fire risks, but these can be minimized or eliminated through smart operational practices, employee training, and advance planning.