Oakton Temp-340 Precision Thermistor Temperature Meter

Overview

The Oakton Temp-340 Precision Thermistor Temperature Meter (Model 91426-50) is a high-resolution, laboratory-grade handheld thermometer engineered for applications demanding traceable accuracy and long-term stability in temperature measurement. Unlike thermocouple-based instruments, the Temp-340 utilizes a precision thermistor sensor—offering superior sensitivity and repeatability within the –40 °C to +150 °C range. Its measurement principle relies on the predictable, non-linear resistance–temperature relationship of metal-oxide semiconductor elements, linearized via embedded NIST-traceable algorithms. Designed for quality control labs, pharmaceutical manufacturing environments, food safety testing, and academic research, the device meets foundational requirements for ISO/IEC 17025-compliant thermal verification workflows. Its compact form factor, IP54-rated enclosure, and sealed membrane keypad ensure operational reliability in moderately challenging environments—including cleanrooms, production floors, and field deployments where dust ingress or incidental splashing may occur.

Key Features

• Ultra-high resolution: 0.01 °C display resolution from –40 °C to 99.99 °C; 0.1 °C above 100 °C
• Industry-leading accuracy: ±0.03 °C at reference points between –40 °C and 99.99 °C—exceeding typical Class A RTD performance in this sub-100 °C domain
• Dual-channel logging capability (via optional external probe interface on compatible models) supports comparative thermal profiling
• 2000-point internal memory with time-stamped data capture, configurable sampling intervals (1 second to 60 minutes)
• USB 2.0 interface enables direct data export to Excel-compatible CSV files without proprietary software
• Backlit LCD with user-selectable °C/°F units, real-time min/max tracking, and hold function for stable readings
• Auto-calibration sequence compliant with ASTM E2877-22 guidelines for thermistor thermometer verification
• Robust ABS housing with IP54 ingress protection; operates continuously for >200 hours on standard AA alkaline cells

Sample Compatibility & Compliance

The Temp-340 is compatible with Oakton’s full suite of thermistor-specific probes—including general-purpose immersion (93824-00), penetration (93824-30), surface-contact (93823-01), and air/gas-sensing (93823-05) variants—all rated for –30 °C to +100 °C operation. While the instrument itself does not include a probe, its input circuitry is optimized for 10 kΩ nominal thermistors with Beta values of 3950 K, ensuring minimal self-heating error (<0.02 °C at 100 µA excitation current). The device complies with IEC 61000-4 electromagnetic immunity standards and conforms to RoHS 2011/65/EU directive requirements. For regulated environments, audit-ready calibration records can be generated per GLP/GMP documentation protocols; firmware supports date/time stamping with user-defined ID fields to satisfy FDA 21 CFR Part 11 electronic record integrity criteria when paired with validated data management systems.

Software & Data Management

Data retrieval is accomplished via native USB HID class communication—requiring no driver installation on Windows, macOS, or Linux platforms. Exported CSV files contain columns for timestamp (YYYY-MM-DD HH:MM:SS), measured temperature (°C), unit designation, and status flags (e.g., “MIN”, “MAX”, “HOLD”). Optional Oakton DataLink™ desktop utility (v3.2+) provides trend visualization, statistical analysis (mean, SD, CPK), and automated report generation aligned with ISO 9001 clause 8.2.4. All firmware updates are delivered as signed binary packages with SHA-256 checksum validation to maintain cryptographic integrity—a requirement under NIST SP 800-53 Rev. 5 IA-7.

Applications

• Pharmaceutical stability testing per ICH Q1A(R2), including accelerated and real-time storage condition monitoring
• Calibration verification of incubators, refrigerated centrifuges, and cold-chain transport containers
• Thermal mapping of sterilization autoclaves and depyrogenation tunnels (when used with validated probe arrays)
• Food processing line validation per FDA Food Code §3-201.11 and HACCP critical control point logging
• Academic thermodynamics experiments requiring sub-0.1 °C resolution in calorimetry and phase-change studies
• Environmental chamber qualification per ISO 14644-3 Annex B and ASTM E747-20 test procedures

FAQ

Does the Temp-340 require annual recalibration?
Yes—Oakton recommends annual calibration against an NIST-traceable reference standard (e.g., Fluke 724 or Hart 1529) to maintain stated accuracy specifications. Internal auto-calibration corrects for drift but does not replace metrological verification.
Can the Temp-340 measure surface temperatures directly?
Only when equipped with a compatible surface probe (e.g., 93823-01); the base unit has no built-in sensor. Contact resistance and emissivity effects must be accounted for per ASTM E1965-16.
Is the USB interface compatible with LabVIEW?
Yes—NI-VISA drivers support direct SCPI-style command querying (e.g., “READ?”, “UNIT:C?”, “CAL:STAT?”) for integration into automated test sequences.
What is the warm-up time to achieve full accuracy?
Less than 30 seconds after power-on, assuming ambient temperature is within specification limits (15–30 °C).
Does the device support alarm output to external PLCs?
No—alarm conditions are visual/audible only. For process interlock integration, use Oakton’s Temp-360 (91426-60) with relay output option.