COMPRESSED AIR, VACUUM, AND GENERATORS In industrial settings, moisture removal from compressed air is critical to maintaining operational integrity. Compressed air dryers support this function across diverse sectors where water vapour, corrosion and airborne contaminants can negatively impact machinery performance and final product quality. They are particularly crucial for industrial applications that require specific air quality thresholds, as classified in ISO 8573-1 for particulates, moisture content and oil, as well as compressed air treatment systems that have been tested against ISO 12500. Ultimately, the purpose of compressed air dryers is to deliver moisture-free air that provides process consistency and equipment longevity. Various dryer technologies employ distinct methods to minimise moisture content through pressure dew point reduction, thereby preventing downstream condensation. Yet the selection process often focuses narrowly on a handful of sizing criteria, overlooking additional variables that prove equally influential in determining system performance, regulatory adherence, and long-term compressed air installation Total Cost of Ownership (TCO) 34 HYDRAULICS & PNEUMATICS June 2026 www.hpmag.co.uk The hidden factors behind compressed air dryer selection Louis Cottaz, Product Manager at Donaldson, looks at hidden factors when choosing the right compressed air dryer. Installation environment Understanding the precise installation environment of the compressed air dryer is crucial. Simply knowing a compressed air dryer will be located “outside” is insufficient because the specific external location introduces a unique set of challenges that can impact the dryer’s performance and lifespan. For example, considerations may include whether the location is at risk of freezing, if there are high ambient temperatures, whether the compressed air dryer will be located in a humid coastal region, or at 2500 meters above sea level with fluctuating temperatures and wind gusts. Location impacts everything from air density and dryer capacity to corrosion protection needs. In areas with heavy rain or snow, enclosure design, drainage and insulation become real performance factors - not just design footnotes. The considerations for a roof installation compared to a ground installation are dramatically different due to environmental extremes and structural issues. For example, there are unique challenges related to roof installations. This includes those related to thermal stress, weather exposure and accessibility, as well as freezing risks such as ice formation in refrigerated air dryer heat exchangers and in condensate management systems. Roofs absorb intense solar radiation and radiate heat from the building below, creating a significantly higher ambient temperature than ground level. This excess heat can drastically reduce the efficiency of refrigerated air dryers, forcing the equipment to work harder and often requiring the unit to be oversized to meet the required dew point. In addition, hot exhaust air from the dryer’s condenser can become trapped and recirculate into the intake on a roof, leading to performance degradation and higher energy consumption. Acoustic profile The acoustic profile of a compressed air dryer is an often-overlooked environmental factor that can present operational concerns. Some air dryer designs may generate noise levels that approach the threshold for hearing protection. In the UK, the Control of Noise at Work Regulations 2005 sets action levels at 80 and 85 dB, while the EU’s Directive 2003/10/EC sets lower exposure action value at 80 dB and upper exposure action value at 85 dBA. Noise emissions are not uniform and vary according to the unit’s underlying moisture removal technology. Desiccant dryers, required for achieving very low dew points, operate with a highly disruptive noise signature due to the purge air exhaust used to regenerate the desiccant material. In contrast, refrigeration dryers present a more consistent but less intense noise problem. Sophisticated silencers included in dryers can help to address this issue. Ongoing maintenance While initial cost and performance ratings may dominate the buying decision, the ease and speed of maintenance are significant contributors to long-term operating costs and production reliability. A compressed air dryer is an integral part of the manufacturing process. When it goes offline for servicing, the production line may be interrupted, often requiring a bypass line or a standby dryer in critical installations. A key question is not just if it can be serviced, but how fast and how
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