Loop checking and calibration — verifying every instrument signal from field to control system and calibrating it to a traceable standard.
Commissioning, FAT & SAT — in depth
Every control loop is only as good as its weakest signal. Loop checking confirms each instrument’s signal travels correctly from field to PLC/SCADA and that outputs drive the right device, while calibration sets each instrument against a traceable reference — the painstaking work that makes control accurate and trusted.
What matters in practice
Field signal traced to the control system.
Instruments set to traceable standards.
Confirm outputs drive correct devices.
Documented results per loop.
| Step | Action | Note |
|---|---|---|
| Trace | Field to PLC | Per loop |
| Calibrate | Traceable | Reference |
| Output | Device check | Verify |
| Record | Loop folder | Evidence |
Continue across this series
A companion deep-dive in this series.
Read MoreA companion deep-dive in this series.
Read MoreA companion deep-dive in this series.
Read MoreThe overview page this topic expands on.
Read MoreThe wider hub for this subject area.
Read MoreReynolds & Bauhm designs and delivers commissioning, fat & sat solutions backed by process engineering and performance guarantees.
Fundamentals, design drivers and practical guidance
Loop checking and calibration — verifying every instrument signal from field to control system and calibrating it to a traceable standard.
Reynolds & Bauhm runs structured FAT and SAT regimes, full loop-check documentation and witnessed performance tests, so plants are handed over proven against specification with a complete, auditable commissioning record — not signed off on optimism.
Commissioning is the disciplined transition from a constructed plant to a proven, operating one, and it is split into clear stages: Factory Acceptance Test (FAT), Site Acceptance Test (SAT), loop checking, and performance testing. Each stage de-risks the next — faults caught at FAT in the supplier's works are an order of magnitude cheaper to fix than the same fault found during live process commissioning on site.
A Factory Acceptance Test verifies the panel, PLC and software against the functional design specification before it leaves the factory: I/O is simulated, interlocks and trips are forced, alarms and sequences are demonstrated, and the client witnesses and signs off. Site Acceptance Test then repeats the critical checks in situ, confirming that field wiring, instruments and final elements behave as the tested logic expects once connected to real plant.
What our engineers assess on every scope of this type
| Parameter | Typical basis | Why it matters |
|---|---|---|
| SAT | Repeated on site | Proves field wiring and instruments |
| Loop check | Every signal, point by point | Confirms path, direction and scaling |
| Interlocks | Cause-and-effect tested | Safety functions proven before run |
| Performance test | Against guaranteed duty | Demonstrates the contract is met |
| Documentation | Signed records per stage | Auditable basis for handover |
| FAT | Witnessed at supplier works | Catches logic/panel faults early and cheap |
Common questions on installation and commissioning
That each instrument's signal reaches the control system at the correct value, and each output drives the correct final element in the correct direction with the correct scaling. It is the foundation that performance testing relies on.
Through a witnessed performance test running the process against its guaranteed duty — flow, removal efficiency and energy — over an agreed period. Meeting the targets over that run is the basis for acceptance and handover.
A complete commissioning pack: FAT and SAT records, loop-check sheets, interlock cause-and-effect results, the performance-test report and a closed punch list — an auditable trail that the plant was proven, not assumed.
Because a fault found in the supplier's works during Loop Checking & Calibration-type checks is far cheaper and faster to correct than the same fault discovered during live commissioning on site. FAT proves the panel, logic and sequences against specification before anything ships.
Our expertise spans multiple industries with sector-specific water treatment solutions.
Explore closely-related topics, equipment and guides
Send your influent analysis and our engineers assess your process and recommend a tailored treatment solution — free, confidential and no obligation.
Select the regulatory standard for your country — it sets which parameters we need for a compliance-aware process assessment.
Required parameters for the chosen standard are flagged on the sample form. You can still submit a partial set and we will advise what else to test.
Your sample is stored against your company so we can track the project. Provide a company name or email as a minimum.