www.hpmag.co.uk Housings and filter elements may not be the most visible part of a filtration system, but they are essential in managing compressed air and gas purity. The housing is the pressurised outer shell that directs the airflow and holds the internal components. Key features of housings include: The head - usually contains the inlet and outlet ports where the air enters and exits the filter. The bowl - the bottom part that collects the liquid (water and oil) captured by the filtration process. The drain - found at the bottom of the bowl. There are usually four types of condensate drains used on compressed air filters: 1) electronically level-controlled drain, 2) electrically time-controlled drain, 3) float drain, 4) manual valve. The electronically level-controlled drain does not release any compressed air from the filter, only the condensate. A filter element is the replaceable insert that sits inside the housing, trapping or separating contaminants. Elements are categorised based on what they are designed to capture, and include: Particulate elements - use a mesh or fibre media to catch solid dust, dirt and pipe scale. Coalescing elements - force small oil and water droplets to merge into larger drops, which then fall into the bowl. Adsorption (carbon) elements - use activated carbon to capture oil vapours and odours that coalescing filters miss. Well-configured filter housings and the right element therefore help capture contaminants such as particles, moisture, oil aerosols and oil vapour – supporting stable performance and 40 HYDRAULICS & PNEUMATICS September 2026 helping extend the life of sensitive equipment. The most effective and reliable filter housings and elements are designed with application and service life in mind. Features like flow-optimised internal geometry and robust construction will support smooth, uninterrupted flow across a wide range of pressures and capacities. Elements should offer high contaminant-holding capacity and filtration performance that supports effective separation of solids, liquids and aerosols. Maintenance and adaptation Filtration needs may change with process updates, flow adjustments or filter media upgrades. Standardised and modular housings and filter configurations in a compressed air filtration system can be adapted over time without redesigning the filtration system. This allows a system to grow and change alongside a business’s The unsung filtration heroes of reliable compressed air Pure, reliable compressed air and gases help to keep industrial operations running smoothly. In compressed air and gas systems, including hybrid applications like air-driven hydraulic pumps and air-over-oil systems that rely on clean plant air to generate hydraulic force, filtration is an active part of process reliability. Wolfgang Bongartz, Global Product Manager Industrial Gases at Donaldson, explains further. SPECIAL REPORTS operational needs instead of replacing an entire installation when requirements shift. Also, high-quality housings are often designed for dual-use, allowing the internal configuration to be flipped to allow air to flow from the inside-tooutside (for removing liquid aerosols) or outside-to-inside (for dry dust), depending on the specific contamination challenge. Modern filtration systems prioritise uptime by making maintenance as fast and infrequent as possible. To help avoid guesswork, smart monitoring systems use differential pressure indicators to alert the operator when the energy cost of a clogged filter exceeds the cost of a new element. Housings made of durable materials can help extend their operational lifespan, even when exposed to the acidic condensate that naturally collects at the bottom of the filter bowl. By using these modular and standardised components, a facility can maintain a living system that is easy to service, cost-effective to operate, and ready to adapt to new technology or production demands. Durable materials and service-friendly designs also support straightforward maintenance to help keep systems running with little interruption. System integrity and compliance In industries where air and gas purity is critical, ISO 8573-1, the global standard for compressed air purity, provides a clear framework for managing air quality, specifying purity classes of compressed air with respect to particles, water and oil independent of the location in the compressed air system at which the air is specified or measured. ISO 8573-1 is essentially a preventative health plan for systems that rely on compressed air. Standardising the quality of air flowing through pipes allows organisations to move from reactive to predictive maintenance to help reduce unplanned Wolfgang Bongartz, Global Product Manager Industrial Gases at Donaldson
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