The award-winning iTHERM TrustSens TM371 sanitary RTD with the world's first self-calibrating Pt100 sensor unit Sanitary RTD iTHERM TrustSens TM371 Sanitary RTD - iTHERM TrustSens TM371Our award-winning iTHERM TrustSens TM371 sanitary RTD features the world's first self-calibrating Pt100 sensor unit. Automate your product safety and compliance!Sanitary RTD - TrustSens TM371 Metric RTD thermometer with self-calibration technology for hygienic applications iTHERM TrustSens is the only self‑calibrating RTD thermometer for hygienic processes, delivering continuous accuracy and compliance without interrupting production. Its fully automated in‑situ self‑calibration and Heartbeat Technology ensure reliable drift detection, audit‑proof documentation, and maximum process efficiency.No plant downtime and reduced operational costs: Fully automated in‑situ self‑calibration without interrupting the process for recalibration.Safe audits and minimized risk: Automatically generated, traceable and audit‑proof calibration certificates.Improved product quality and process safety: Continuous device monitoring and verification with Heartbeat Technology, including automated loop checks.Highest measurement accuracy thanks to individual sensor‑transmitter matching performed at the factory.Easy handling: iTHERM TrustSens comes preconfigured for quick integration; simply connect and start measuring. Guided wizards support intuitive commissioning.Digitally future‑ready: 24/7 access to all calibration data, including cloud‑based availability via Netilion.Measuring range: -40 to 190 °C (-40 to 374 °F)Sensor: Pt100 with accuracy class A according to IEC 60751; sensor response time t90: < 2.0 sSterile and hygienic process connections, e.g. Thread, Clamp, APV-Inline, Varivent, DIN 11851Designed for critical hygienic / aseptic applications in the life sciences, food and beverage industry118 °C (244 °F) calibration point for steam‑based processes, e.g. Sterilization‑In‑Place (SIP). 39 °C (102 °F) calibration point for e.g. Cleaning‑In‑Place (CIP), pasteurization, distillation. Hygienic- and food safety compliance: EHEDG, ASME BPE, FDA, 3‑A, EC 1935/2004, EC 2023/2006, EU 10/2011.Instrument approvals: CE/EAC, CRN, CSA, explosion protection e.g ATEX/IECEx.Compact sanitary RTD - iTHERM TrustSens TM371 with self-calibrating Pt100 sensor and iTHERM QuickNeck quick-release neck for fast insert removalSanitary RTDs, such as the compact iTHERM TrustSens TM371 temperature measurement device, are available with special elbow thermowells in hygienic design for clean processes and accurate measurementsOur sanitary resistance thermometer is recognized by numerous industry awards for its breakthrough technology, including the prestigious HERMES AWARD iTHERM TrustSens with patented iTHERM QuickNeck for all hygienic and aseptic applications Temperature measurement is a critical part of sterile process applications. iTHERM TrustSens supports automation of product safety and compliance.For which applications are self-calibrating thermometers suitable?iTHERM TrustSens covers a wide range of applications across Food & Beverage and Life Sciences processes, particularly those involving critical control points (CCPs): measurement points where product safety or quality depends on maintaining tight temperature limits. Two different calibration points are available, which ensure reliable self-calibration under typical operating conditions. 118 °C (244 °F) calibration pointSterilization-in-place (SIP) & steam-in-place processesUHT milk processingMedical autoclavesSterile fillingEdible oil refining39 °C (102 °F) calibration pointCleaning-in-place (CIP) processesBioreactors and fermentersWFI loops and hot storageFluidized bed dryingCoating processesBlood plasma fractionationActive pharmaceutical ingredients (API) productionEthylene oxide sterilization Is a calibration at one temperature sufficient to detect a drift over the whole measurement range?In hygienic and aseptic applications, RTD drift is dominated by offset shifts of the resistance temperature characteristic rather than changes in slope or non-linearity. If a deviation is detected at a stable reference point, the entire characteristic curve is, in almost all cases, shifted practically in parallel. As a result, verifying accuracy at one physically stable reference temperature provides a reliable indication of accuracy across the full process temperature range.This behavior has been scientifically analyzed by the Technical University of Ilmenau, Germany. When measurement uncertainty is considered, iTHERM TrustSens remains well within the tolerance limits commonly applied in hygienic and life science processes.In addition, the one-point calibration of iTHERM TrustSens achieves a very low calibration uncertainty, comparable to or better than many onsite three-point calibrations performed with mobile block calibrators.Does iTHERM TrustSens self-calibration replace manual calibration in regulated industries? What if my SOP requires a three-point calibration?The decision to replace or reduce manual calibration remains the responsibility of the plant operator and must be based on the applicable regulatory and quality requirements.The primary intention of the technology is to eliminate the need for routine manual calibrations defined in SOPs (standard operating procedures) by providing continuous, traceable verification of sensor accuracy directly under real process conditions. Manual calibrations can, of course, still be carried out at any time if required. According to GMP (A Risk-Based Approach to Calibration Management) Appendix I, an initial annual or biannual manual calibration interval is recommended for devices with low risk. iTHERM TrustSens calibrates regularly and therefore the risk of undetected drift is as low as it gets. For processes with existing SOPs, calibration intervals can be extended in a risk‑based manner, based on continuous calibration data generated over time, without increasing overall process risk.What is the difference between calibration and verification in temperature measurement?Calibration and verification are fundamentally different concepts and are not interchangeable.Calibration compares a measuring device against a traceable reference standard under defined conditions. It determines the actual measurement deviation and quantifies measurement uncertainty. The result is documented in a calibration certificate and can be used in regulated and audited environments. iTHERM TrustSens performs a true self-calibration. It is using an integrated physical reference point.Verification, by contrast, confirms that a device is functioning within predefined limits and verifies sensor health. It can detect anomalies or sensor drift, but it does not determine the actual measurement accuracy, quantify uncertainty, or provide a calibration certificate. Other solutions on the market are based on sensor redundancy, NTC sensors, drift monitoring, or plausibility checks and use verification methods. Is manual field calibration more accurate than automated self-calibration?No. Typical onsite manual calibrations using dry block calibrators achieve uncertainties around ±0.75 K, influenced by installation, heat transfer and handling. iTHERM TrustSens achieves lower system uncertainty (down to ±0.35 K) and calibrates inline under real process conditions. How can I reduce calibration costs and plant downtime for temperature measurement?The self-calibrating thermometer iTHERM TrustSens helps reduce operational expenses (OpEx), resulting in a reduced total cost of ownership (TCO) over the lifecycle.Eliminate the risk of undetected temperature drift: It performs an automatic in‑process calibration every time the device reaches its built‑in reference point. This eliminates undetected drift, which could lead to costly consequences, e.g. incomplete sterilization / insufficient heating in critical applications. The financial impact of such drift strongly depends on the specific application and regulatory environment, but avoiding these risks can reduce potential follow‑up costs.Extend or replace manual calibration intervals: Because the device performs fully automated self‑calibrations, it can replace routine manual calibrations or significantly extend existing intervals. The actual savings depend on the amount of manual calibrations and whether it replaces all manual calibrations or the interval to be lengthened.How can a self-calibrating thermometer be integrated into existing quality and compliance systems?Self‑calibration supports quality assurance and compliance by verifying the temperature measurement in process, without stopping production, and by keeping the measurement point under continuous control.It also strengthens data integrity and audit readiness because the system can generate automated, audit‑proof calibration certificates as standardized evidence. In addition, self‑calibration produces structured calibration information (e.g. deviation and calibration counter) that can be reviewed and integrated into control/QA workflows. With appropriate system integration, this enables early warnings/alarms before a deviation becomes critical, supporting proactive deviation management and CAPA triggers. Overall, it fits well with the FDA’s lifecycle approach to process validation, where stage 3 emphasizes ongoing/continued process verification to demonstrate a sustained state of control.How long-term stable is the integrated reference of iTHERM TrustSens? Is a recalibration of the reference required? Long‑term stability is achieved through an integrated ceramic reference sensor based on the Curie temperature. The Curie point is a material constant that does not drift over time, making it a stable physical fixpoint, comparable to the freezing point of water. iTHERM TrustSens does not rely on a calculated temperature value; instead, it directly detects the magnetic phase transition at the Curie point. Because only the occurrence of this magnetic change is detected, the reference remains inherently stable and does not require periodic checks or recalibration throughout the entire device’s lifetime. While recalibration of the reference is not required, verification using standard dry‑block or oil bath calibrators is possible by comparing the measured temperature with the iTHERM TrustSens reference value. What happens when iTHERM TrustSens detects a deviation during operation?iTHERM TrustSens provides clear deviation information both locally at the measuring point via LED and centrally in the control system via 4-20 mA / HART. Sensor drift warning: If the measured deviation exceeds the warning limit (default: ±0.5 °C) but remains below the alarm limit, the LED flashes red/green. The temperature output remains valid, while the HART status changes to Maintenance required (NAMUR NE107). Sensor drift alarm: If the deviation exceeds the alarm limit (default: ±0.8 °C), the LED turns to a steady red light. The device switches the 4-20 mA output to error current and reports a Failure status via HART. The warning and alarm thresholds are configurable parameters in the device and can be adapted to regulatory requirements or SOP defined tolerance limits. In addition to the HART status the device continuously transmits its most recent calibration deviation value using the HART “QV” variable.Does iTHERM TrustSens self-calibration need to be triggered manually, or does it run automatically?Self‑calibration runs fully automatically and does not require any operator intervention. The Curie temperature of each iTHERM TrustSens is defined prior to delivery at either 118 °C (244 °F) or 39 °C (102 °F), depending on the application. Whenever the process temperature passes this defined point during normal operation, for example during cooling after steam sterilization or cleaning‑in‑place, the self‑calibration is performed automatically. Once the Curie temperature is reached, the integrated reference sensor generates a signal while a parallel measurement is performed by the Pt100 element. The comparison of these two values constitutes self-calibration. Can calibration be performed without stopping production? Yes, with the iTHERM TrustSens self-calibrating thermometer. The temperature output is not affected and therefore production continues without interruption, eliminating downtime while maintaining full traceability and compliance. Self‑calibration with iTHERM TrustSens takes place inline and automatically when the process temperature passes the integrated Curie reference point (e.g. after SIP/CIP). The 4–20 mA measurement signal remains continuously available during self‑calibration. Calibration and diagnostics run independently of the temperature output to the control system.Is a manual loop check still required when using iTHERM TrustSens?No, iTHERM TrustSens offers a function to perform an automatic loop check. In critical processes, loop integrity equals product safety. That’s why in a traditional workflow, the loop check takes place together with the manual calibration or directly afterwards. iTHERM TrustSens includes a patented built‑in 4–20 mA loop check function that allows verification of the entire signal path from the thermometer through cabinets, barriers and wiring to the PLC. The loop check:simulates three configurable mA values,automatically triggers low and high failure currents,keeps the digital HART value available during the simulation.The loop check can be performed manually or fully automated, for example through a control system routine that automatically reads back and verifies the relevant values.Is iTHERM TrustSens accuracy Class A or Class AA?According to IEC standards, Class A / AA accuracy apply exclusively to the bare RTD sensor element. However, iTHERM TrustSens is a complete measuring system consisting of: RTD sensor, transmitter, signal processing. Each TM371 undergoes individual sensor–transmitter matching. Rather than specifying only the tolerance of the sensing element, Endress+Hauser specifies the performance of the measuring point. As example the uncertainty at 135 °C (275 °F):iTHERM TrustSens: < +-0.22 KRTD Class AA sensor (+-0.33 K) + temperature transmitter iTEMP TMT72 (+-0.07 K): +-0.38 KCombined with in-line self-calibration against a stable physical reference, TM371 ensures high measurement accuracy and long-term stability under real process conditions. The achievable system accuracy is generally higher and more consistent than that obtained using Class A or AA RTD sensors without individual matching or continuous calibration monitoring.Find more information in the technical information, chapter 14.4. How can I access the calibration certificates created by iTHERM TrustSens? Can I have them automatically exported and ready to use in a QA system?iTHERM TrustSens stores the last 350 self-calibrations. To access the certificates, simply open the device setup via the driver (DTM, FDI) and execute the export. In addition to that, Endress+Hauser offers a combination to automate generation and export of certificates to a defined network folder while also storing them in a database. This allows seamless integration into existing QA systems.To realize this, up to 20 iTHERM TrustSens can be connected to one Advanced Data Manager Memograph M RSG45 which reads the calibration data and stores the certificates. To regularly and automatically export the certificates from Memograph M RSG45, the free software Field Data Manager can be used. What if my process rarely (or never) reaches the self-calibration temperature 118 °C (244 °F) or 39°C (102 °F)?Self‑calibration depends on the process temperature crossing the calibration point and the cooling rate being within the defined limits. If these preconditions are not met, iTHERM TrustSens offers the possibility to set a counter, enabling the device to flag a status via HART (NE107 categories) if self-calibration is overdue. In addition to the HART status, the device continuously transmits a calibration counter using the HART “TV” variable. You can also put a threshold on it that it must increase every x days in the control system.