Vacuum cleaning system eliminates dangers of combustion

Proper vacuum cleaning of powder paint booths crucial to safety, throughput, and profit

By Plant Engineering Staff June 27, 2003

by Ed Sullivan

Although the powder coating process offers important advantages that make it the finish of choice among manufacturers of industrial and consumer products—beautiful cosmetic appearance, durability, overall quality, and economies—the process also introduces health and safety issues that make cleanup of powder coating booths far more important than merely necessary housekeeping.

Worker exposure to inhalable particles, the possibilities of powder combustion, and environmental damage are all potential hazards that must be dealt with by manufacturers who use powder-coating technology. While the basic requirements to minimize these hazards are spelled out by OSHA and other agencies, it is also clear that the avoidance of some risks can be determined by the choice of an ancillary tool that is needed in the powder-coating booth—the vacuum cleaner.

Some powder coating operations inadvertently use the familiar “shop-type” vacuums to clean their powder coating booths. This is especially common among manufacturers who are new to the powder coating technology. While the”shop-type” vacuums may be appropriate for some light-duty cleanups, they are generally unsafe for use in a powder spray booth. Furthermore, the use of an inappropriate vacuum cleaning system may cause the powder spray operation to lose economies from the recovery and reuse of overspray powder, and incur the added expense of having to dispose of wasted powder.

“Combustion of powder coatings can occur when a deposited layer of powder comes in contact with a source of ignition, such as static electricity generated by ungrounded vacuum cleaners,” warns Steve LaFever, an engineer with Phoenix Wire Cloth, Inc., Troy, MI. “Powder flowing in one direction through a vacuum-cleaning hose will create a significant static electric charge. Plus, there is the possibility that there is static electricity build-up on the powder coating deposits. If an ungrounded hose used to vacuum overspray powder were to contact an object that was grounded, the static electricity could then arc and trigger a violent explosion.”

Powder combustion has also resulted in raging fires that have caused catastrophic damage to factory facilities and have resulted in costly shutdowns.

LaFever says Phoenix Wire Cloth, which has manufactured wire mesh and related product for over a century, wanted to purchase an industrial-grade vacuum cleaning system to provide the needed safety plus other important benefits to its powder coating operation.

Phoenix Wire Cloth had converted its metal finishing process to powder coating about five years ago. The company, which manufactures a wide range of wire mesh-based products, such as wire baskets, partitions, guards, cloth and security fencing, also uses a wide range of metals to fabricate screen, including stainless steel, bronze, aluminum, copper, tinned steel, and high-temperature alloys. The powder coat finishing process is applied to its safety systems, including robotic enclosures, wire mesh partitions, stair rail inserts, machinery guards, and focal displays.

“We were a perfect candidate for powder coat finishing technology, and a perfect candidate for a vacuum-based cleaning and recovery system,” says LaFever, who headed up the selection of a new vacuum system last fall. The potential LaFever saw was for faster turnaround on setups for new paint colors plus a certain amount of savings by recovering powder overspray, as well as an improved safety factor.

Phoenix Wire Cloth normally uses three basic colors in its powder coat operation, although special colors and clear-coat are also available. Each time a color change is required, the powder spray booth has to be cleaned, and overspray must be vacuumed out of the spray booth. Some products, such as safety fences, receive two or three different colored fences. Otherwise, powder colors are changed at intervals subject to sales orders.

“The safety fences that we manufacture are powder coated in a rather small booth, approximately 3 ft. by 12 ft.,” LaFever explains. “And we have limited space available for an additional powder coating and baking facilities. So, by speeding up the cleanup process, we are speeding up overall productivity for powder-coated products.”

One of the ways cleanup time could be improved was to make sure that a squeegee was integrated into the vacuum system. There was also a likely substantial saving in labor over the old method, which included a “shop-type” vacuum and wipe down of the spray booth by hand.

Because color changes occur on an as-needed basis, it is hard to say how much money the company was likely to save through recovery and reuse of powder overspray. LaFever was aware that recovery was often a significant factor in powder coat operations, so he decided that the new vacuum system should have separate recovery canisters for different powder colors. Not only would that enable reuse of the powder, but it would obviate the need to treat the powder as hazardous waste — another savings.

Once the vacuum cleaning system specifications were decided, Phoenix Wire Cloth sought bids from several suppliers. “Surprisingly, there was a wide range of prices, and varying apparent interest among vendors,” LaFever says. “Among others we contacted Heneveld Group in Zeeland, MI, because of an article I read about a vacuum system they distributed.”

The system that Heneveld represents is VAC-U-MAX, a premier brand in the vacuum cleaning and conveying industry. Although VAC-U-MAX did not offer the lowest cost products, they did offer a wide range of solutions, including one that Phoenix Wire Cloth would meet all its specs at the best price.

“The system we ultimately selected was a standard VAC-U-MAX‘workhorse’ model, a portable 55-gallon unit with changeable collection containers,” LaFever says. “The VAC-U-MAX system is completely grounded, so there is no danger of an explosion or fire resulting from static discharges during vacuum clean-up operations. The system is quite powerful andincludes a wand and squeegee, so we can clean the walls and floor of the spray booth much more quickly. We purchased three collection canisters, which allows us to recover our three basic colors in separate containers for later reuse. Basically, the cleanup operation is now just a matter of blowingout the hoses and vacuuming the powder.”

LaFever says that the most meaningful savings with the new VAC-U-MAX cleaning system is on labor, although productivity improvements and powder recovery should also prove to be substantial. “With the material savings, the savings will mount up, but it’s actually relative to the number of times we change color in the spray booth. We may be running a color for four days before we have to make a change, then need to change color again within a day. So, material savings will be a function of how often we have to clean up the stray booth. As for the risk of static electric discharge, we are confident that it has been minimized,” LaFever says.

VAC-U-MAX offers the industry’s only written static control guarantee which is provided with its Venturi compressed air-powered vacuums with anti-sparking vacuum inlets and grounding lugs. Optional stainless steel anti-sparking construction of the cover, suction inlet, and all internal contact parts, excluding the filter, can now minimize the possibility of sparking resulting from dynamic contact between the suction inlet and particles drawn into it. Static conductivity from end to end, including a static conductive hose with internal ground wire and grounded end cuffs, further prevents static build up.

Together these measures safeguard the cleanup of excess powder from fires or explosions related to static discharge or accidental electrical ignition. Optional static-conductive filters, rated 99.9% efficient at one micron, further reduce sparking danger, while virtually eliminating any fine particle discharge from the vacuum’s exhaust back into the work area.

David Kennedy, Sales Manager for the VAC-U-MAX vacuum cleaning product line, says powder-coating operations are a very popular application for VAC-U-MAX systems. “We have customers who have the need for the same functionality and benefits as Phoenix Wire Cloth, and some who have other needs. For example, some customers need a vacuum cleaning system that can support continuous operation, so that powder is cleaned up before it can be transported on conveyor belts that carry freshly coated products. Some want electric-powered systems; others require air power. Certain operations are concerned with noise or need certain accessories or adapter devices. Whatever their need, we feel it is vital to offer them the right system and components.”

VAC-U-MAX systems are sold worldwide, with major markets for vacuum cleaning systems, including the metalworking, chemical, and food and pharmaceutical industries. Industrial vacuum cleaners range from small air- and electric-powered drum-style units to large electric and diesel units offering a choice of discharge into drums, bulk bags, hoppers, or roll-off containers. Centralize unites can hook up to fixed piping networks or clean out silos. Options include continuous dual-pulse filter cleaning, HEPA filtration, custom control packages, and intercept hoppers. Standard airflow ranges are between 100 CFM and 1000 CFM.

For more information about VAC-U-MAX industrial vacuum cleaning or pneumatic material handling solutions, contact VAC-U-MAX by mail at 37 Rutgers Street, Belleville, NJ 07109; telephone (800) 822-8629 or (973) 759-4600; E-mail: ; or visit the web site .