When to Bring the Calibrator to the Sensor — and When Not To
The decision between portable (in-house) calibration and lab (outsourced) calibration comes down to one question: who moves — the sensor or the calibrator? The answer depends on sensor installation, accuracy requirement, volume, and documentation standard.
Send the Sensor to the Lab, or Bring the Calibrator to the Sensor?
Send the sensor to the lab when…
Sensor requires NABL-accredited calibration for regulatory submission or customer audit
Accuracy requirement is tighter than your in-house calibrator can achieve
Sensor is removable and can be sent without disrupting the process for an extended period
Volume of sensors is low (1–5 per year) and instrument investment is not justified
Multi-point calibration with certificate at closely-spaced intervals is required
Bring the calibrator to the sensor when…
Sensor is permanently installed and removal would require process shutdown or re-certification
Volume of calibrations justifies in-house instrument investment (typically >10 instruments/year)
Quick turnaround is required — lab lead times of days/weeks are unacceptable
Field commissioning of newly installed instruments — calibrate before plant handover
Routine QA checks where in-house documentation is sufficient (not regulatory submissions)
Portable Calibration
What Portable Calibration Enables
Portable dry block calibrators allow a calibration technician to bring the reference temperature to any sensor location — whether on a production line, in a cold room, on a plant roof, or at a customer site. The sensor stays installed; no process interruption is required.
Production line maintenance
Verify process thermocouples and RTDs without production shutdown
Field instrument commissioning
Calibrate newly installed sensors before plant handover
Cold room and cold chain verification
Sub-zero portable dry block calibrates temperature sensors in situ
Service and repair validation
Confirm sensor replacement is within specification before signing off
Limitations: Portable calibrators achieve ±0.2–0.5°C uncertainty — adequate for most industrial applications but not for pharmaceutical IQ/OQ multi-probe mapping or NABL reference lab work. They also calibrate one probe at a time in field use.
A controlled laboratory environment provides lower measurement uncertainty than field calibration. The ambient temperature is stable, the equipment is isolated from vibration, and the reference standard (typically a precision liquid bath with an SPRT reference probe) is optimised for accuracy.
Lab calibration remains the standard for: pharmaceutical sensor certification, NABL-accredited certificates for regulatory submissions, initial calibration of new working standards, and any application where the measurement uncertainty must be documented and defensible.
Indeecon NABL Calibration Service
Indeecon's NABL-aligned calibration service provides accredited calibration certificates for temperature instruments across the full range of industrial applications.
The Practical Approach: Portable for Verification, Lab for Certification
Most industrial sites use a two-tier calibration programme: portable dry block calibrators for routine field checks and interim verification between formal calibrations; and periodic lab calibration (NABL-accredited) for the annual or bi-annual certification used in regulatory submissions, supplier audits, and quality system records.
This approach provides immediate on-site detection of sensor drift while maintaining the rigorous traceable documentation required by quality and regulatory systems.
Popular Equipment
Popular Equipment for Portable and Lab Calibration
These linked instruments support the most common in-house and lab-adjacent calibration workflows discussed on this page.
