ISOTECH TRU938 Thermocouple Reference Junction (Ice-Point & Adjustable Temperature Calibrator)
| Brand | ISOTECH |
|---|---|
| Model | TRU938 |
| Origin | USA |
| Type | Thermocouple Reference Junction Unit |
| Operating Ambient Temperature Range | 2–65 °C |
| Stabilization Time | ≤10 min (to setpoint, even at max ambient) |
| Reference Temperature Options | 0 °C (ice-point equivalent) or adjustable 45–70 °C |
| Temperature Stability | ±0.05 °C (at setpoint, steady-state) |
| Alarm Threshold | ±0.2 °C deviation from setpoint |
| Cooling/Heating Principle | Solid-state Peltier thermoelectric module |
| Enclosure Rating | IP20 (indoor laboratory use) |
Overview
The ISOTECH TRU938 Thermocouple Reference Junction is an electronically controlled, solid-state thermal reference unit engineered for high-accuracy cold-junction compensation and reference temperature generation in thermocouple calibration, verification, and metrology workflows. Unlike traditional ice-bath assemblies, the TRU938 employs a precision Peltier thermoelectric module to actively maintain a stable, traceable reference temperature—either 0 °C (functionally equivalent to the ITS-90 ice-point definition) or an adjustable range between 45 °C and 70 °C. This dual-mode capability supports both conventional cold-junction simulation and elevated-reference applications required in high-temperature thermocouple system validation (e.g., Type K, N, R, S, B). Its design complies with fundamental requirements of ASTM E230/E230M (Standard Specification for Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples) and ISO/IEC 17025:2017 clause 6.4.6 on reference equipment stability and uncertainty contribution. The unit delivers sub-0.05 °C thermal stability under steady-state conditions, with minimal drift (<0.01 °C/h) and no reliance on consumables such as ice, water, or refrigerants.
Key Features
- Solid-state Peltier architecture eliminates mechanical compressors, moving parts, or phase-change media—ensuring long-term reliability and maintenance-free operation.
- Rapid thermal stabilization: achieves target temperature (0 °C or user-selected point within 45–70 °C) in ≤10 minutes, even when operating at maximum ambient temperature (65 °C).
- Dual-reference mode: configurable for either fixed 0 °C simulation (aligned with ITS-90 ice-point convention) or programmable elevated reference points—supporting thermocouple loop checks, transmitter calibration, and multi-point system verification.
- Integrated digital temperature alarm: triggers visual and audible alert if measured junction temperature deviates by ≥±0.2 °C from setpoint—enabling real-time monitoring during critical calibration procedures.
- Robust aluminum chassis with passive thermal shielding minimizes external ambient influence; validated performance across 2–65 °C ambient range ensures operational flexibility in non-climate-controlled labs or production floor environments.
- Front-panel LED display with 0.01 °C resolution and intuitive push-button interface for immediate setpoint selection, status feedback, and alarm reset—no PC required for basic operation.
Sample Compatibility & Compliance
The TRU938 accommodates standard thermocouple wire gauges (AWG 20–32) via dual universal terminal blocks supporting bare-wire insertion or miniature connector (MJ) interfaces. It is compatible with all base-metal and noble-metal thermocouple types (J, K, T, E, N, R, S, B, C) and supports both single- and dual-junction configurations. The unit meets essential environmental and safety requirements per IEC 61010-1:2010 (Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use) and carries CE marking for EMC compliance (EN 61326-1). For accredited calibration laboratories, its documented thermal stability, linearity, and repeatability data support uncertainty budgeting per ISO/IEC 17025:2017 Annex A.3, and its digital alarm function aligns with GLP audit expectations for procedural integrity during temperature reference verification.
Software & Data Management
While fully functional as a standalone instrument, the TRU938 includes an RS-232 serial interface (with optional USB-to-serial adapter) for integration into automated calibration systems. ISOTECH provides a lightweight Windows-based configuration utility enabling remote setpoint adjustment, alarm threshold modification, firmware updates, and time-stamped logging of temperature readings (sample rate: 1 Hz). All logged data export to CSV format for traceability and post-processing in Excel or LIMS platforms. Audit trail functionality records user-initiated changes (e.g., setpoint edits, alarm resets), satisfying documentation requirements under FDA 21 CFR Part 11 (when used with validated software configuration and electronic signature controls).
Applications
- Primary cold-junction reference in thermocouple calibration laboratories performing ISO/IEC 17025-accredited calibrations.
- Field-deployable reference source for on-site verification of temperature transmitters, DCS inputs, and SCADA thermocouple channels.
- Elevated-reference validation of thermocouple extension wiring, compensating cable performance, and junction box thermal uniformity.
- Supporting ASTM E220, E230, and IEC 60584-1 test protocols requiring stable, known reference temperatures for EMF measurement uncertainty reduction.
- Education and training environments where reproducible, safe, and repeatable thermocouple fundamentals instruction is required—eliminating hazards associated with ice baths or liquid nitrogen.
FAQ
Does the TRU938 require periodic recalibration?
Yes—ISOTECH recommends annual traceable calibration against a certified reference thermometer (e.g., PRT or SPRT) per ISO/IEC 17025 requirements. Certificate of Conformance (CoC) is supplied with each unit; optional UKAS-accredited calibration certificate available.
Can the TRU938 be used for thermocouple wire annealing?
No—the TRU938 is not designed for thermal cycling or high-current annealing processes. It maintains a stable reference temperature only; it does not provide the sustained elevated heat or current control required for wire homogenization.
Is the 0 °C output traceable to ITS-90?
Yes—the 0 °C mode is factory-adjusted and verified using NIST-traceable standards to match the ITS-90 defined ice-point temperature (273.15 K) within ±0.02 °C uncertainty at time of shipment.
What is the maximum number of thermocouple wires supported simultaneously?
The TRU938 features two independent terminal blocks, each accepting up to four wires (eight total), allowing parallel connection of multiple thermocouple circuits for batch verification or redundancy testing.
Does ambient humidity affect performance?
The unit is rated for operation at up to 80% RH non-condensing. Internal thermal management prevents condensation ingress; however, prolonged exposure above 65 °C ambient or >80% RH may impact long-term stability and is outside specified operating conditions.
