| Supplier and factory identity | Confirm the legal entity, manufacturing address, business scope, and whether production is performed in-house or outsourced. | Consistent company and factory details across business documents, quotations, audit records, and contracts; clear disclosure of outsourced processes. | Unclear factory location, inconsistent entity details, or refusal to distinguish manufacturing from trading activities. |
| Membrane specifications | Review the membrane material, module configuration, dimensions, nominal pore size or molecular-weight cut-off, and applicable operating limits. | A product data sheet states the test method and conditions. The supplier explains that pore-size or cut-off figures are product-specific and should be checked against the intended application. | Vague or conflicting specifications, or performance claims presented without test conditions or supporting documentation. |
| Performance data | Ask for test results covering relevant measures such as permeate flux, rejection or retention, and integrity, where applicable. | Results identify the test water or feed, temperature, pressure or transmembrane pressure, test duration, and measurement method. Data are relevant to the proposed use. | Guaranteed flux or removal figures with no stated feed conditions; results that cannot be connected to the offered product or module. |
| Quality management and traceability | Check quality procedures, incoming-material controls, production inspections, finished-product checks, and batch identification. | Documented quality controls and traceable production or inspection records. Any ISO certificate is current, verifiable, and relevant to the stated site and scope. | A certificate is offered as the only proof of product performance, or batch and inspection records are unavailable. |
| Chemical cleaning and operating limits | Verify allowable pH, temperature, pressure, cleaning chemicals, concentration, and exposure time for the specific membrane model. | Written operating and cleaning guidance is model-specific and consistent with the product data sheet and warranty terms. | General cleaning advice that omits concentration or exposure limits, or operating conditions that conflict across documents. |
| Application experience | Discuss experience with the relevant water source and treatment objective, such as drinking-water pretreatment, wastewater reuse, or process-water treatment. | The supplier asks about feed-water quality, target water quality, capacity, pretreatment, and operating conditions before recommending a membrane. | A product is recommended without reviewing feed-water conditions or the intended system design. |
| Sampling and pilot testing | Determine whether samples, a trial, or a pilot test can be arranged before a large order. | A test plan defines the feed, operating conditions, duration, measurements, and acceptance criteria; results are recorded and shared. | Pressure to place a large order based only on brochure claims or tests with no agreed method. |
| Production capacity and lead time | Check available capacity, production schedule, standard and custom options, and the basis for quoted lead times. | Lead times and quantities are stated in the quotation or contract, with a clear process for communicating production changes. | Unrealistic delivery promises or no written confirmation of production and shipment milestones. |
| Warranty and after-sales support | Review warranty duration, exclusions, claim evidence, replacement terms, technical support, and spare-parts availability. | Terms are written, product-specific, and clear about how operating conditions and maintenance affect a claim. | Verbal assurances that are absent from the contract, or warranty terms that do not define coverage and exclusions. |
| Export and shipment documentation | Confirm the agreed Incoterms, packaging, shipping marks, document set, and any destination-market requirements. | The supplier confirms responsibilities and documents in writing and can provide relevant product and shipment records for the order. | Unclear allocation of freight, insurance, customs, or documentation responsibilities. |
| Commercial terms and contract | Compare quotation validity, payment schedule, currency, order specifications, inspection terms, and remedies for nonconformity. | The contract identifies the exact model and specifications, quantity, delivery terms, inspection basis, and process for resolving discrepancies. | Payment or product terms differ between the quotation, purchase order, and contract, or key specifications are left undefined. |
| Total cost of ownership | Consider purchase price alongside energy use, cleaning needs, expected replacement intervals, maintenance, and system compatibility. | Cost comparisons use stated assumptions and account for the complete operating system, rather than relying on unit price alone. | Lowest-price claims are treated as proof of lower lifecycle cost without supporting operating data. |