RTD Calibration: Turnaround Times, On-Site Services & How It Works
Tra-Cal Lab has provided ISO/IEC 17025 accredited, NIST-traceable RTD calibration for over 35 years — trusted by NASA, the U.S. military, and NIST. We service every major brand, from industrial PT100 probes to laboratory-grade reference sensors, with faster turnaround and lower cost than the OEM. We offer expedited services, on-site calibration and Mid-Atlantic pickup and delivery to keep your operation running. Every certificate includes as-found/as-left data, so your measurements stand up to any audit.
Key Summary
RTD calibration measures the sensor’s resistance against a NIST-traceable standard at multiple temperature set points in a controlled bath or dry-block, then fits the results to the appropriate characterisation — IEC 60751 tolerance class or, for reference-grade probes, Callendar–Van Dusen coefficients, with results documented on a calibration certificate. Standard turnaround is 3-5 business days with overnight rush available, and most RTDs should be calibrated every 12 months by an ISO/IEC 17025 accredited lab.
Why Choose Tra-Cal?
ISO/IEC 17025 Accredited
Our lab is independently audited every year by ANAB to the industry's most rigorous quality standard, so every calibration is audit-proof.
Overnight Rush Available
When downtime isn't an option, expedited service gets your instrument calibrated and back in your hands overnight or within three days.
NIST-Traceable
Every measurement we make traces directly back to national standards, giving your results documented accuracy you can defend.
Trusted by NASA, the U.S. Military, and NIST
The organizations with the most demanding measurement requirements in the country choose Tra-Cal — yours can too.
RTD Calibration Turnaround
| Service | Turnaround |
|---|---|
| On-site Calibration Service | Same-Day |
| Standard calibration with certificate | 3-5 business days |
| ISO/IEC 17025 accredited calibration | 4-6 business days |
| Expedited / rush | Overnight to 3 days |
RTD Brands & Models We Calibrate
| Manufacturer | Popular Models We Calibrate |
|---|---|
| All major RTD and temperature-probe manufacturers | Contact Tra-Cal for the current list of models we calibrate |
Don’t see your model?
We support over 100 test equipment manufacturers — contact us and we’ll confirm coverage for your exact instrument.
Equipment & Standards Required
We maintain the following equipment and conditions required to calibrate an RTD accurately:
NIST-traceable standard platinum resistance thermometer with at least a 4:1 test accuracy ratio
Stirred liquid baths and dry-block calibrators covering the required span with documented stability and uniformity
Precision thermometry bridge or resistance ratio bridge with four-wire, low-self-heating measurement
Manufacturer’s calibration procedure and the applicable IEC 60751 tolerance-class limits
Stable environment: 23 °C ± 5 °C, controlled humidity, and NIST-traceable reference standards with a documentation system
How to Calibrate an RTD: Step-by-Step
Step 1: Inspect the probe and check insulation resistance. Examine the sheath, seal, and lead wires for damage or moisture ingress, measure insulation resistance between the element and sheath, and confirm the wiring configuration before any thermal work.
Step 2: Perform “as found” verification. Record resistance and the derived temperature at each set point before any action. As-found data proves whether the process controlled by this sensor was actually running at the recorded temperature.
Step 3: Compare against the reference at each set point. Insert the probe and the standard to the same immersion depth, allow full stabilization, and measure resistance with a low sense current to avoid self-heating — then verify the ice-point resistance (R₀) as the anchor for the whole characterisation.
Step 4: Characterise, repair, or reject as required. Report deviations against the IEC 60751 tolerance class, or fit Callendar–Van Dusen coefficients for reference-grade probes. Sensors showing drift, shunting, or insulation failure are documented and returned as limited-use or rejected.
Step 5: Perform “as left” verification and issue documentation. Re-run the set-point series after any repair and issue an ISO/IEC 17025 accredited certificate with as-found and as-left data, the coefficient set or correction table, measurement uncertainties, and NIST traceability.
Pro tip from our lab: Always request as-found/as-left data on your certificate. Without it, you can’t assess whether measurements taken before calibration were reliable — a common audit finding.
How Often Should You Calibrate an RTD?
| Usage Profile | Recommended Interval | Notes |
|---|---|---|
| Daily industrial / field use | 6–12 months | Shorten after drift or overload events |
| General lab / bench use | 12 months | Industry-standard default |
| Regulated environments (ISO 9001, FDA, A2LA audits) | Per quality system, typically 12 months | Interval must be documented and justified |
ISO/IEC 17025 does not specify fixed calibration intervals. It requires that intervals be reviewed and adjusted as necessary to maintain confidence in the equipment. Recommended intervals are typically 6–12 months, adjusted based on documented risk assessment and historical stability data per the lab’s calibration program. A2LA and ANAB are accreditation bodies — distinct from quality-system frameworks such as ISO 9001 or FDA requirements.
Frequently Asked RTD Questions
Q: How much does RTD calibration cost?
A: RTD calibration cost depends on the temperature range and number of set points required, whether a simple tolerance-class check or full Callendar–Van Dusen coefficients are needed, the wiring configuration (2-, 3-, or 4-wire), and whether accredited (17025) certification is needed, and whether accredited (17025) certification is required. Contact Tra-Cal for a quote.
Q: Can I calibrate an RTD myself?
A: You can perform verification checks against a known reference, but formal calibration requires traceable standards with a 4:1 accuracy ratio and documented uncertainty.
Q: What is the difference between calibration and adjustment?
A: Calibration is the documented comparison against a standard; adjustment is the correction made when readings fall outside tolerance.
Q: How long does calibration take?
A: Standard turnaround is typically 3-5 business days; Tra-Cal offers expedited service options.