| 1 | Match the Filter to the Air-Service Requirement | Confirm the intended medium, operating pressure, temperature, nominal flow rate, connection size, and installation direction. For compressed-air systems, identify the required ISO 8573-1 purity class for particles, water, and oil. | Product datasheet; application questionnaire; pressure–flow chart; dimensional drawing; operating-temperature and pressure-range statement. | The stated flow must be measured at clearly defined inlet conditions, and the maximum working pressure and temperature must exceed the actual system requirements with an appropriate engineering margin. | Flow rate shown without test conditions; missing pressure rating; unclear filter orientation. |
| 2 | Check Filtration Performance and Pressure Drop | Verify particle-removal performance, oil-aerosol performance where applicable, water-separation capability, initial pressure drop, and recommended element-replacement pressure drop. | Independent or controlled laboratory test report; test method; pressure-drop curve; filtration-efficiency data; definition of particle size and test contaminant. | Performance claims should identify the test method and operating point. Do not compare efficiency percentages unless the particle size, loading condition, and test method are equivalent. | “99.99% filtration” with no particle size, test method, or pressure-drop data. |
| 3 | Verify Materials and Mechanical Construction | Review housing material, element media, seals, drain design, corrosion resistance, thread or flange standard, and compatibility with lubricants, condensate, and ambient conditions. | Material specification; seal-material declaration; corrosion-resistance information; assembly drawing; bill of materials; incoming-material inspection records. | Materials must be suitable for the stated pressure, temperature, fluid, and environment. Critical dimensions and connection standards must match the approved drawing. | Generic “metal housing” description; no seal specification; inconsistent dimensions between drawing and sample. |
| 4 | Validate Quality-System Controls | Determine whether the manufacturing site operates a documented quality-management system and whether production controls cover incoming materials, assembly, leak testing, calibration, and final inspection. | Valid ISO 9001 certificate showing the actual manufacturing site and scope; audit summary; inspection plan; calibration records; nonconformance and corrective-action procedure. | The certificate should be issued by an accredited certification body, remain within its validity period, and cover the relevant design or manufacturing activities. | Certificate belongs to a trading office; expired certificate; scope does not cover the supplied product. |
| 5 | Confirm Applicable Regulatory Certifications | Identify destination-market requirements. Pressure equipment may fall under the EU Pressure Equipment Directive 2014/68/EU when its scope and pressure category apply. CE marking is a conformity indication, not a universal product-quality certification. | Declaration of Conformity; technical file summary where available; risk assessment; pressure-category classification; notified-body documentation when required; applicable local compliance records. | Certification and declarations must identify the correct product range, manufacturer, applicable legislation, standards used, and authorized signatory. Requirements must be checked against the destination country. | CE logo without a Declaration of Conformity; certificate for a different model; no explanation of applicable legislation. |
| 6 | Audit Testing, Traceability, and Inspection Records | Check whether each unit or batch can be traced to materials, production date, inspection results, and operator or equipment records. Confirm pressure, leakage, dimensions, and visual-finish inspections. | Sample inspection report; batch or serial-number system; pressure-test record; leak-test record; calibration certificates for measuring equipment; pre-shipment inspection checklist. | Test records should be dated, signed or electronically approved, linked to the purchase order or batch, and based on defined acceptance limits. | Blank inspection forms; handwritten results with no batch link; calibration certificates unavailable. |
| 7 | Review Documentation, Serviceability, and After-Sales Support | Confirm that installation, operation, maintenance, drain handling, replacement-element identification, storage, warranty, and spare-parts information is complete and consistent. | User manual; installation drawing; spare-parts list; maintenance interval; replacement-element specification; warranty terms; packaging and storage instructions; English-language technical documents. | Documents should show the exact model or product family, revision date, operating limits, safety warnings, and measurable maintenance criteria. Spare parts should be identifiable without ambiguity. | Marketing brochure used as a manual; no replacement-element code; warranty excludes normal filter service without clarification. |