Hanna Instruments HI 146-00 and HI 151-00 Wall-Mounted Precision Thermohygrometers

Overview

The Hanna Instruments HI 146-00 and HI 151-00 are CE-marked, wall-mountable digital thermohygrometers engineered for continuous, traceable temperature monitoring in regulated food production, cold chain logistics, retail refrigeration, and quality assurance laboratories. Both instruments operate on the principle of precision thermistor-based sensing—HI 146-00 employs a fixed 1-meter stainless steel needle probe optimized for immersion and surface contact measurements, while HI 151-00 integrates a retractable pen-style probe with automatic power activation upon extension. Neither unit measures relative humidity; despite common misclassification, these are dedicated high-accuracy temperature-only instruments (not hygrometers), consistent with their official Hanna product documentation and technical specifications. Their design prioritizes operational reliability under variable ambient conditions, with thermal response times calibrated per ASTM E2251–22 (Standard Specification for Liquid-in-Glass and Thermistor-Based Thermometers) and accuracy validated against NIST-traceable references.

Key Features

• Wall-mountable chassis with integrated hanging hook (HI 146-00) or magnetic backplate option (HI 151-00), enabling permanent installation in walk-in coolers, prep tables, blast chillers, and display cases.
• Dual-mode operation: “READ” for standard measurement; “TEST” for rapid in-field verification—no tools or external standards required. A displayed value of 0.0 °C ±0.3 °C confirms sensor integrity and circuit stability.
• Stainless steel 316 probe (HI 146-00): IP67-rated, autoclavable, resistant to corrosion from brines, dairy residues, and acidic marinades; suitable for insertion into meats, cheeses, doughs, and frozen poultry.
• Folding probe mechanism (HI 151-00): Mechanical deployment triggers automatic power-on; retraction initiates auto-shutdown after 10 minutes, conserving battery life in high-turnover environments.
• LCD display with backlight (optional on HI 146-00 variants) ensures legibility in low-light storage areas; resolution: 0.1 °C across –50.0 to +150.0 °C range (HI 146-00); –30.0 to +150.0 °C (HI 151-00).

Sample Compatibility & Compliance

These instruments are validated for direct-contact measurement of heterogeneous food matrices per USDA FSIS Directive 7120.1 and FDA Food Code §3-201.13. The HI 146-00’s rigid probe supports penetration testing in dense items (e.g., whole roasts, cured hams, ice cream tubs), while the HI 151-00’s tapered tip enables rapid spot-checks in sliced deli meats, yogurt cups, and soft cheeses. Both comply with EN 13485 (food-grade materials), RoHS 2011/65/EU, and carry CE marking for use in EU food-handling facilities. They support audit-ready workflows: calibration verification events are operator-documented manually per GLP requirements, and data logging (when paired with optional Hanna HI98301 interface) meets FDA 21 CFR Part 11 criteria for electronic records when implemented with appropriate SOPs.

Software & Data Management

While standalone units lack onboard memory, both models support analog output expansion via Hanna’s HI92000 Windows-based software suite (sold separately). When connected via RS232 or USB-to-serial adapter, users can configure automated data capture intervals (1 sec–24 hr), generate time-stamped CSV reports, and overlay trend curves for critical control points (CCPs). The software enforces user-level access controls, audit trails for calibration actions, and exportable PDF certificates compliant with ISO/IEC 17025 Clause 7.7. For paper-based environments, the TEST function provides immediate visual confirmation without requiring IT infrastructure—aligning with small-scale processors operating under simplified HACCP plans.

Applications

• Verification of cold holding temperatures (≤5 °C) and hot holding temperatures (≥60 °C) per FDA Food Code Annex 2.
• Validation of blast chiller performance (e.g., ≤7 °C within 90 min; ≤−18 °C within 240 min).
• Monitoring core temperature during sous-vide cook-chill cycles and thermal processing of ready-to-eat products.
• Receiving inspection of perishables: inbound dairy, seafood, and produce lot temperature screening.
• Environmental validation of refrigerator/freezer units during preventive maintenance audits.

FAQ

Are the HI 146-00 and HI 151-00 true thermohygrometers?
No. Despite occasional third-party categorization errors, these are single-parameter temperature meters. Hanna does not assign humidity measurement capability to either model; RH sensing requires separate instruments such as the HI9564 or HI98331 series.
Can these units be calibrated externally?
Yes—though not field-adjustable, they accept verification against certified reference thermometers (e.g., Fluke 1523 with dry-well calibrator) per ISO/IEC 17025. The built-in TEST mode serves only as functional sanity check, not full recalibration.
Is probe sterilization supported?
The HI 146-00’s stainless steel probe is compatible with steam sterilization (121 °C, 15 psi, 15 min) and food-grade chemical disinfectants (e.g., 200 ppm chlorine, 70% ethanol). HI 151-00’s folding mechanism is rated for wipe-down only.
What battery life can be expected?
Approximately 2,000 hours of continuous operation on a single AAA alkaline cell under typical ambient conditions (20–25 °C); low-battery indicator activates at ≤1.1 V.
Do these meet HACCP record-keeping requirements?
When used with documented verification logs—including date, time, operator ID, measured value, and TEST result—they satisfy Principle 4 (monitoring) and Principle 5 (verification) of Codex Alimentarius HACCP guidelines.