Agree what acceptance means before manufacturing
A membrane plant purchase should establish how the delivered equipment will be checked against the quotation. The inspection plan should identify tests, responsibilities, instruments, pass criteria and records. Release for shipment, acceptance of the installation and performance acceptance are useful separate milestones, even where the contract links them.
IEC 62381:2024 provides a framework for acceptance testing of automation systems. Its scope does not automatically turn a FAT into proof of desalination output, salt rejection or energy consumption. These process requirements and the method used to verify them must be expressly included in the project specification.
What a useful FAT can cover
A proposed protocol can cover equipment identification, agreement with approved drawings, assembly, maintenance access, instrument signals, PLC sequences, alarms, interlocks and response to a power interruption. Each test should distinguish simulated inputs from conditions that were physically measured.
Hydraulic checks need a procedure compatible with the allowable pressures of the complete assembly. Record whether membranes are installed, which water is used and how the equipment will be preserved before commissioning. Do not assume the workshop has the feed supply, electrical capacity or discharge arrangements needed to reproduce the full process.
| Test | Factory FAT | Site SAT |
|---|---|---|
| Controls and alarms | Sequences with real or simulated signals | Response with equipment and utilities connected |
| Hydraulics | Workshop circuit and available conditions | Integration with intake, tanks and outlets |
| Quality and output | Only what the test water can demonstrate | Verification against agreed feed and method |
| Documentation | Drawings, equipment lists and test records | Final revision and closed outstanding items |
What SAT adds after installation
The project site introduces conditions that the workshop may not represent: inlet pressure, electrical supply, ambient temperature, permeate backpressure, pretreatment and concentrate disposal. SAT should check the interfaces and operation of the connected equipment within the contracted scope.
Prepare a readiness checklist identifying available utilities and who supplies them. Where the customer provides water, air, chemicals or external piping, their availability affects testing. Before travelling, agree who collects samples, supplies measuring instruments and reviews the results.
Specify a meaningful performance test
Define feed composition and temperature, net product output, recovery, required quality, available pressure and supply boundaries. Specify test duration, stabilisation, logging frequency and repeat-test criteria. For UF, state whether the accepted volume excludes backwashing, cleaning and water diverted because it does not meet specification.
For RO, performance comparisons should account for temperature and composition changes using the agreed method. DuPont describes normalisation as a way of separating these effects from actual performance changes. Normalisation does not make any available test water equivalent to evidence of operation with the design feed.
Example: testing seawater RO with mains water
Consider a SWRO plant intended to produce 40 m³/h under defined seawater conditions. The workshop uses mains water to check signals, valves and operating sequences. This is useful evidence, but its observed flow does not establish production of 40 m³/h at the design salinity and temperature.
The test report should identify what has been demonstrated and which items remain for later verification. If factory performance testing is required, agree a suitable test installation, water composition, concentrate handling and evaluation method. The cost and practical feasibility belong in the quotation rather than being discovered when the equipment is ready to ship.
Close outstanding items and retain the operating baseline
The final report should include measured results, instruments used, deviations and outstanding actions with an owner and due date. Photos or a video showing a running skid help document the event, but do not replace traceable records assessed against acceptance criteria.
Retain the initial operating data and the documentation supplied to the operator: final drawings, manuals, spare-parts list and maintenance instructions within the agreed scope. This baseline supports later investigation of production losses and gives both parties a reference when assessing performance under changing site conditions.
Common questions
Does a passed FAT mean the plant has been commissioned?
No. It confirms only the factory checks recorded in the report. Installation, integration and commissioning at the project site require their own verification.
Does SAT always include an extended performance trial?
Only when specified. The contract should define duration, acceptable feed conditions, indicators and the procedure for accepting or repeating the trial.