Thermoprobe TL2 High-Precision Dual-Channel Digital Thermometer

Overview

The Thermoprobe TL2 is a high-stability, dual-channel digital thermometer engineered for laboratory-grade temperature metrology where traceability, repeatability, and long-term stability are critical. It employs precision 4-wire resistance measurement of platinum RTD sensors (200 Ω nominal) using constant-current excitation and low-noise ratiometric ADC architecture—eliminating lead resistance errors and minimizing self-heating effects. Unlike thermocouple-based instruments, the TL2 delivers absolute temperature measurement referenced directly to the ITS-90 scale via NIST-traceable calibration at multiple points across its full operating range (–20 °C to +150 °C). Its microprocessor-controlled thermal compensation algorithm actively corrects for internal thermal gradients within the instrument housing, ensuring measurement integrity even under variable ambient conditions. Designed for integration into validation workflows, the TL2 meets foundational requirements for ISO/IEC 17025-accredited laboratories and supports GLP-compliant documentation through its audit-ready calibration history.

Key Features

• Dual independent channels with simultaneous real-time readout and differential temperature calculation
• 0.001 °C resolution with ±0.03 °C accuracy (at 23 °C ambient), certified per NIST-traceable calibration report
• Rugged powder-coated steel enclosure (IP65 ingress protection) suitable for benchtop, cleanroom, or controlled environmental chambers
• Optimized 4-wire RTD interface via standardized 5-pin DIN connector—ensures compatibility with industry-standard 200 Ω Pt RTDs (e.g., ASTM E1137 Class A)
• Internal rechargeable battery providing up to 50 hours of continuous operation; intelligent low-power management extends service intervals
• Thermal drift compensation across –20 °C to +54 °C operating ambient range—critical for stability during extended thermal mapping studies
• No external AC power dependency: operates exclusively on battery, eliminating ground-loop interference in sensitive measurement setups

Sample Compatibility & Compliance

The TL2 is designed exclusively for use with 200 Ω, 4-wire platinum resistance thermometers meeting IEC 60751 or ASTM E1137 specifications. It does not support thermocouples, thermistors, or semiconductor sensors. Each unit ships with a factory calibration certificate documenting as-found and as-left values at three reference points (–20 °C, 25 °C, and 150 °C), fully traceable to NIST SRM 1750a (Standard Platinum Resistance Thermometer). The instrument complies with electromagnetic compatibility requirements per EN 61326-1:2013 for laboratory equipment and satisfies mechanical robustness criteria outlined in MIL-STD-810G Method 516.6 (shock and vibration). For regulated environments, the TL2 supports 21 CFR Part 11-compliant data logging when paired with Thermoprobe’s optional TL-Link software and secure USB interface.

Software & Data Management

While the TL2 operates autonomously without software, optional Thermoprobe TL-Link PC application enables time-synchronized dual-channel data acquisition, statistical analysis (min/max/mean/delta), and automated report generation in PDF or CSV format. All logged measurements include embedded timestamps, channel identifiers, and instrument serial number—supporting ALCOA+ data integrity principles (Attributable, Legible, Contemporaneous, Original, Accurate). Audit trails record user login events, calibration updates, and configuration changes. Firmware updates are delivered via signed binary packages verified through SHA-256 hash validation, ensuring integrity during field deployment.

Applications

• Validation of autoclaves, stability chambers, incubators, and environmental test chambers per ISO 13485 and FDA Guidance for Industry
• Calibration transfer between reference standards and working thermometers in metrology labs
• In-process monitoring of exothermic reactions and thermal curing profiles in R&D synthesis
• Temperature uniformity mapping (TUM) in pharmaceutical lyophilizers and freeze dryers
• Reference-grade verification of IR thermometers and infrared thermal imagers
• Long-duration thermal aging studies requiring sub-millidegree stability over multi-day cycles

FAQ

Is the TL2 compatible with 100 Ω or 1000 Ω RTD sensors?
No. The TL2 is hardware-optimized for 200 Ω, 4-wire platinum RTDs only. Using other sensor types will result in incorrect scaling and invalid measurement uncertainty budgets.
Does the instrument require periodic recalibration?
Yes. Thermoprobe recommends annual recalibration against a NIST-traceable standard, especially when used in GxP-regulated applications. Calibration interval may be extended based on risk assessment per ISO/IEC 17025 Clause 6.6.
Can the TL2 operate while charging?
No. The battery must be fully charged prior to deployment; the unit does not support concurrent operation and charging.
What is the maximum cable length supported between the TL2 and RTD probe?
For optimal accuracy (<±0.002 °C additional error), Thermoprobe specifies ≤1.5 m standard cable. Custom shielded cables up to 5 m are available with pre-compensated lead resistance correction.
Is the display readable under low-light or glove-compatible conditions?
Yes. The high-contrast monochrome LCD features backlighting with adjustable intensity and supports operation with nitrile or latex gloves due to its tactile button layout and responsive membrane switches.