FAT and SAT have complementary jobs. A factory acceptance test can check the agreed fabrication, assembly, controls, documentation, and simulated functions available before shipment. A site acceptance test checks actual utilities, integration, source-water behavior, operating sequence, and the site conditions that cannot be reproduced in the factory.
Set the acceptance basis before testing
The test plan should be traceable to the approved design basis, supply scope, drawings, datasheets, controls narrative, and commercial agreement. Define what will be witnessed, what evidence will be recorded, which conditions cannot be tested until site, and how deviations will be classified and closed.
Avoid describing FAT as a full performance guarantee where actual water, utilities, external equipment, or site interfaces are not available. Likewise, SAT should not be expected to recreate factory fabrication checks that were already completed and documented.
- Controlled document baseline
- Witness and evidence requirements
- Factory-only versus site-only checks
- Deviation and closeout procedure
Use FAT for fabrication, controls, and documentation
A factory test may review equipment identification, assembly, accessible valves and instruments, control-panel functions, alarms, interlocks, simulated signals, documentation, packing, and agreed integrity checks. The exact scope depends on the contract and available test media.
The result should be a clear record of what was tested, under which conditions, what was witnessed, and what remains open. A signed checklist is more useful when it references drawing revisions, serial information where applicable, and evidence files.
- Mechanical and documentation review
- Controls, alarms, and interlocks
- Agreed testing evidence
- Shipment and preservation record
Use SAT for the real site
SAT begins after the installation, external utilities, tie-ins, safety arrangements, and source-water availability have been checked. It can confirm sequencing, communication, operator workflow, sampling, alarms, external interfaces, and the behavior of the approved process under actual site conditions.
Commissioning frameworks emphasize structured verification and handover rather than a single on/off event.[1] The site plan should identify training, records, spare parts, consumables, unresolved items, and the responsibilities for each completion stage.
- Utilities and tie-in verification
- Actual source-water and operating sequence
- Operator training and handover
- Punch-list and closeout record
Make unresolved items visible
A sound FAT/SAT process does not conceal open points. Record the item, evidence, owner, risk, workaround, due date, and final closure. Examples can include missing utility data, late owner decisions, external equipment, site access, water quality changes, or documentation updates.
This protects both the buyer and supplier from treating an assumption as a completed test. It also produces an operating record that can be used after handover.
- Open-item register
- Owner and target date
- Temporary controls or workarounds
- Final closeout evidence
Related Engineering Resources
Frequently Asked Questions
Does FAT replace site commissioning?
No. Factory checks and site commissioning address different conditions. The site stage verifies actual utilities, interfaces, source water, and operation.
Should acceptance criteria be created after equipment delivery?
No. The test basis, evidence, deviations, responsibilities, and closeout procedure should be defined before testing begins.
Sources & Reading Notes
These sources support the engineering context of this guide. Final project decisions remain subject to current water data, owner requirements, applicable rules, and approved design documentation.
- DuPont Water Solutions — RO/NF FilmTec Technical ManualRO operating and documentation context.
- SFPUC — Commissioning Onsite Water Reuse SystemsStructured commissioning framework context.