Source: Bendix Tech Tips post excerpt
ELYRIA, Ohio – Where the pneumatic brake systems on yesterday’s trucks relied primarily on valves with mechanical seats and springs, commercial vehicles today come equipped with increased automation, and more sophisticated computer-controlled solenoid valves that can cycle more frequently and have tighter tolerances. This installment of the Bendix Tech Tips series focuses on air-quality requirements and how to make sure your compressor is delivering air that will keep your vehicle’s connected systems operating safely.
Air Quality: Not Just Dry, but Clean
“Defining ‘high-quality’ air is difficult, because there isn’t an industry standard,” said Rich Nagel, Bendix director of marketing and customer solutions – Air Supply & Powertrain. “And yet, because systems today are more sophisticated than they used to be, they also require a higher quality of air.”
Dryness contributes to air quality, Nagel noted, and is probably the first thing that comes to mind when a fleet thinks about air. While the air dryer removes water from the air system, compressed air also contains other contaminants, including oil aerosols and in some extreme cases, oil vapors. The air dryer wasn’t traditionally equipped to remove these types of more contaminants, and if they pass into the air system, they can cause problems in connected systems like brake valves, emissions controls, and automated manual transmissions.
High-quality air isn’t just dry: It’s clean. No system can prevent all contaminants, particularly oil, but the goal, Nagel said, is to minimize what gets into the service tanks. And that’s where a high-performance air compressor and oil-coalescing technology are important.
“Oil-coalescing air dryer filters have been used on trucks for almost 10 years, and most air dryers now come standard with them,” Nagel observed. “What differentiates an oil coalescing cartridge from a regular dryer cartridge is an additional filter that removes oil aerosols that are passed along by the compressor. These are collected into larger drops, and then gravity-fed into the bottom of the cartridge where they’re expelled during the purge cycle.”
While the design of these cartridges differs by manufacturer – the oil-coalescing filter can be placed so the air passes through it before the desiccant or after – all of them offer some level of oil protection, especially when new. Over time, design variances will provide different efficiencies, and they can’t remove oil vapors – but oil-coalescing filters can be very effective at removing most of the oil particulates that a compressor passes into the air system.
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