Compressed air is critical for operations

"When the air goes down, we're dead in the water," says Sandy Muir, vice president of facility management at Caliber Collision Centers, a chain of 65 collision repair shops located throughout Southern California and Texas. "Until we got the right compressor technology, I would get a call that one or two shops were down every day, waiting for service technicians to get them back up and running."

Since collision work is a continuous flow, air system downtime often delayed deliveries of a whole chain of technicians, processes and cars.

"This situation was intensified by our need for clean air, including providing a pure supply to our paint systems and tools as well as the breathing system that delivers fresh air via masks to our paint spray technicians," says Muir.

Caliber had used or evaluated several types of air compressor systems, including piston-driven models and rotary screw designs. Piston-style compressors rely on intake and exhaust valves, which tend to wear and eventually leak, Muir said. Once that happens, oil and sometimes fuel can get into the air system, which affects the purity of the system and causes maintenance problems.

Caliber also used rotary screw compressors, but Muir said he was disappointed with the inherent volumetric and efficiency problems due to the "blow hole" and air leakage (back to the intake) characteristics of those compressors. In order to keep up air volume, rotary screw compressors run at higher speeds, which are detrimental to service life, he said.

"The pressure buildup at the end of the screws is so high and so hot, it burns out the bearings," says Muir. "Plus, they could never keep the back end of the screws together because of the axial thrust; so, they just kept adding more and bigger bearings."

Caliber purchased their rotary vane compressors from Lans Company in Glendora, Calif., a major distributor of compressed air systems.

"One problem with rotary vane compressors was the use of Bakelite vanes," says Stuart Silverman, Lans president. Users should opt for cast iron models with an effective oil system, which minimizes wear, he said. Rotary vane compressors that use bushings instead of bearings should last longer.

Silverman adds that the volumetric efficiency of these compressors is approximately 90 percent, supplying a reliable continuous volume of air while also providing a substantial savings in energy, wear-life and maintenance costs.

Since installing the rotary vane compressors at every location, Caliber has experienced few problems. "I may get a call once a month," says Muir.

He said the new compressors not only meet the reliability requirement, but also reduce cycle time, which is an important advantage from both an operational and competitive standpoint.

Having continuously available compressed air that is consistently clean provides other advantages to those in the auto body repair business.

"Customers are driving more expensive cars with more expensive finishes in recent years," Muir says. "For that reason our industry receives continuous scrutiny from customers as well as stringent guidelines from agencies such as insurance organizations and California's Bureau of Automotive Repair. The whole industry has become very high tech; every car has to have electronic readouts, we use electronic measuring systems for our frame alignment equipment. Paints have become very exotic and expensive. You don't want to have to paint a car twice because of an air pressure problem. Not only will it cost the time to remove and redo the paint, but the material itself is now very expensive."

Muir said Caliber is converting to water-based paints to comply with California state safety requirements. Muir said he thinks the advanced compressor system will help protect that major investment.

Some rotary vane compressors are easier to maintain and service because they require fewer repairs and longer intervals than their piston or rotary screw counterparts. Assembly and dismantling of the compressor can be carried out using standard tools. Easy dismantling of the machine into subassemblies makes fault diagnosis less of a chore.

"We don't normally perform any service on these compressors," Muir says. "We have Lans handle all service throughout the air system, including air dryers and our breathing system. In our business, we know that air is the heart of it. When we call and say that we have an air problem, we need quick response and knowledgeable service."

Muir said his firm requires a partner when it comes to air systems. He said it is frustrating to deal with multiple vendors on multiple systems that are integrated.

"They can give you a runaround," he says. "Like when we might have an air dryer down and the air dryer technician points to the air compressor and says that's where the problem is. We don't want anybody passing the buck like that. So, we want a partner who is an air specialist to take care of it all. And having that kind of relationship has really paid off."

While the cost of electric power needed to drive its compressors is not a major issue with some users, excessive use of power may be a significant cost that is often swept under the rug. For example, older models of compressors often cause a spike in the electric power load during peak usage periods, resulting in a demand profile that could drive up a shop's costs.

"In some businesses, such as body shops, the air compressor is the biggest piece of equipment," says Silverman. "Relatively speaking, it can cause a lot of expense."

On some models, a "part winding start" can be installed to allow the motor to ramp up to speed, which lowers the usage spike during peak periods. Making the peak smaller can lower electric bills. And the savings could justify the cost of a high-efficiency air compressor.

"Shops that are running 60 horsepower compressor motors could save as much as $1,000 per month," Silverman says.

Ed Sullivan is a technology writer based in Hermosa Beach, Calif.