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Key takeaways
- Calibration compares an instrument with a trusted reference, corrects it if needed and records the result.
- Drift is gradual and silent; scheduled checks catch it before it affects quality, safety or compliance.
- Set intervals from how critical the measurement is, the manufacturer’s advice, any regulatory rules and the instrument’s history.
- On-site calibration keeps disruption low, and a certificate turns the result into evidence.
Every decision trusts a measurement
Control loops, alarms, billing and compliance reports all assume the instruments are telling the truth. The accuracy and reliability of the devices that monitor, control and supervise your processes is vital, which is why calibration belongs in every maintenance plan.
What calibration actually involves
- Compare: apply known inputs from a reference standard and record what the instrument reads.
- Adjust: if the error is outside tolerance, correct the zero and span, then check again.
- Record: document the as-found and as-left results, the reference used and the date, so the result can be traced.
Signs an instrument has drifted
- Readings that disagree with a neighbouring instrument or a lab sample.
- A control loop that hunts or needs constant manual correction.
- Alarms that trip too early, too late or not at all.
- Totals, such as flow for billing, that do not match expectations.
How often to calibrate
There is no single right interval. Base it on:
- Criticality: safety, product quality and compliance measurements deserve shorter intervals.
- Manufacturer advice: the catalogue usually recommends a starting interval.
- Regulations and contracts: some measurements have intervals set for you.
- History: if as-found results are always well within tolerance, the interval can often be extended; if not, shorten it.
On site or in the workshop?
Testing on site reduces disruption because the instrument stays in place, and it checks the whole installation, not just the device. Some instruments still benefit from a workshop calibration against higher-grade references.
What a good calibration record contains
For the dissolved oxygen sensors at IWK Sunway Kayangan we handed over a final calibration report and certification. A good record names the instrument and tag, the reference standard and its traceability, the as-found and as-left results, the tolerance and the next due date.
How we help
We provide periodical and preventive maintenance, tailor-made to your specification, with on-site testing and accuracy verified against the relevant standards. The result is fewer instrument-related failures and less downtime.
