| Filter Category | EN 1822 and ISO 29463 | ULPA filters are generally classified from U15 to U17 under EN 1822. | Confirm that the requested product is tested and classified as ULPA rather than being described only as “high efficiency.” |
| U15 Efficiency | EN 1822 | Minimum integral efficiency: 99.9995% at the most penetrating particle size (MPPS). | Suitable when the installation requires very high particle removal but does not require the highest ULPA class. |
| U16 Efficiency | EN 1822 | Minimum integral efficiency: 99.99995% at MPPS. | Select for applications requiring an additional efficiency margin, provided the HVAC system can handle the associated resistance. |
| U17 Efficiency | EN 1822 | Minimum integral efficiency: 99.999995% at MPPS. | Use only when the contamination-control risk assessment justifies the higher pressure-drop and energy requirements. |
| ISO 29463 Equivalence | ISO 29463-1 classification | Common corresponding levels are ISO 50 U for U15, ISO 55 U for U16, and ISO 60 U for U17. | Request the exact standard and classification because terminology and reporting formats may differ between markets. |
| Test Particle Size | EN 1822 / ISO 29463 | Performance is evaluated at the MPPS, which is commonly within approximately 0.1–0.3 μm for many filter designs. | Do not compare efficiencies measured at different particle sizes without reviewing the complete test report. |
| Individual Filter Leak Test | EN 1822 / ISO 29463 | A complete filter should be individually tested for local penetration or leakage by scanning or an approved equivalent method. | Require a serial-numbered test record or certificate traceable to the individual filter where critical containment is required. |
| Airflow Capacity | Manufacturer performance curve and system design | The rated airflow depends on face area, pleat geometry, media type, and allowable pressure drop; no single airflow value applies to every mini-pleated filter. | Compare filters at the same airflow, face velocity, temperature, and test method. |
| Initial Pressure Drop | Product-specific laboratory data | A practical comparison range for compact ULPA designs is often about 250–600 Pa at the specified rated airflow; actual values can be outside this range. | Select the lowest resistance that meets the required efficiency, airflow, size, and service-life targets. |
| Final or Recommended Replacement Resistance | HVAC commissioning criteria and filter supplier data | A common replacement trigger may be approximately 2–3 times the initial pressure drop, but the approved value must be defined for the specific system. | Use a differential-pressure gauge or sensor and follow the equipment manufacturer’s limit rather than relying on a universal value. |
| Filter Media | Application-specific construction | Microglass fiber media is widely used for ULPA filtration; synthetic media may be used in selected designs if the required classification is demonstrated by testing. | Evaluate efficiency, pressure drop, mechanical strength, humidity resistance, and compatibility with the process environment. |
| Pleat Configuration | Product design specification | Mini-pleated construction increases media area within a compact depth and can reduce resistance compared with a flat media panel of the same face size. | Check pleat stability, separator or bead integrity, media-to-frame sealing, and resistance to vibration during transport and operation. |
| Frame Material | Project environmental specification | Common options include anodized aluminum, galvanized steel, stainless steel, and moisture-resistant engineered materials. | Use stainless steel or another corrosion-resistant option in humid, corrosive, or frequent-cleaning environments. |
| Gasket and Seal | Housing design and installation standard | Continuous polyurethane, gel, or elastomeric gaskets may be used depending on the housing and service conditions. | Match the gasket position and material to the terminal housing; even a high-efficiency filter cannot compensate for a bypass leak. |
| Typical Face Velocity | Cleanroom and HVAC design practice | Approximately 0.45 m/s is a commonly used reference for some terminal clean-air applications, but required velocity is system-specific. | Use the airflow and uniformity requirements of the room, terminal housing, and process rather than selecting by velocity alone. |
| Temperature and Humidity | Media, adhesive, gasket, and frame specifications | Operating limits vary by construction; high humidity, condensation, and elevated temperature can affect media strength, adhesive performance, and sealing. | Obtain documented operating limits and avoid condensation or liquid-water exposure unless the filter is specifically designed for it. |
| Fire Performance | Applicable local fire and building requirements | Fire classification depends on the complete filter construction, including media, frame, adhesive, gasket, and protective components. | Request the relevant fire-test documentation for the destination market and installation type. |
| Cleanliness and Packaging | Project cleanliness protocol | Filters for critical clean areas should be sealed, protected from impact, and packaged to minimize particulate contamination before installation. | Check packaging integrity, storage conditions, orientation marks, and installation protection requirements. |
| Dimensional Tolerance | Housing and project specification | The required dimensions, gasket location, and mounting details must correspond precisely to the terminal housing. | Confirm length, width, depth, flange arrangement, gasket position, and access direction before ordering. |
| Service Life and Energy Use | System energy assessment | Fan energy is strongly influenced by pressure drop and operating hours; longer service life does not automatically mean lower total cost. | Compare total cost of ownership, including initial resistance, replacement interval, energy consumption, labor, and disposal. |
| Documentation Package | Quality and validation requirements | A suitable package may include a product specification, dimensional drawing, efficiency classification, pressure-drop curve, leak-test report, and material declarations. | Prefer traceable documentation that identifies the tested model, airflow, test method, acceptance criteria, and production batch. |
| Installation and Acceptance | Commissioning and in-situ testing requirements | After installation, the filter and housing should be checked for bypass leakage, correct seating, airflow, and pressure drop according to the project protocol. | A compliant factory test does not replace correct installation and on-site acceptance testing. |