KEM WBGT-302 Wet-Bulb Globe Temperature Index Meter

Overview

The KEM WBGT-302 Wet-Bulb Globe Temperature Index Meter is a precision-engineered portable instrument designed for real-time assessment of thermal stress in occupational environments. It calculates the Wet-Bulb Globe Temperature (WBGT) index—a standardized composite metric defined by ISO 7243:2017 and JIS B 7922-2017—using simultaneous measurements of natural wet-bulb temperature, black globe temperature, and dry-bulb (ambient) temperature. For outdoor conditions, WBGT is computed as: 0.7 × T_wb + 0.2 × T_g + 0.1 × T_db; for indoor or shaded settings, the formula is: 0.7 × T_wb + 0.3 × T_g. This index serves as the primary physiological indicator for heat strain evaluation in industrial hygiene, occupational safety, and environmental health monitoring—directly supporting compliance with OSHA guidelines, ACGIH TLVs®, and national standards including GB/T 17244–1998, GBZ/T 189.7–2007, and GBZ 2.2–2007.

Key Features

• Integrated triple-sensor architecture: independently calibrated thermistors for natural wet-bulb (ventilated), black globe (50 mm copper sphere, matte black finish), and ambient air temperature, plus capacitive relative humidity sensing.
• IP65-rated enclosure: dust-tight and protected against low-pressure water jets from any direction—validated per IEC 60529—ensuring operational reliability in demanding field environments such as construction sites, power plants, steel mills, and agricultural facilities.
• High-resolution 2.8-inch LCD display (56 mm × 42 mm active area) with backlight for legibility under direct sunlight or low-light conditions.
• On-device threshold alarm: user-configurable WBGT limit triggers audible and visual alerts to support immediate intervention during heat exposure events.
• Extended data logging capacity: stores up to 30,000 timestamped measurement records internally, each including WBGT, T_wb, T_g, T_db, RH%, and measurement time (YYYY-MM-DD HH:MM:SS).
• USB Type-C interface: enables high-speed data export to PC-based analysis software, firmware updates, and continuous operation via external 5 V DC power supply.

Sample Compatibility & Compliance

The WBGT-302 is optimized for ambient air sampling in static and low-air-velocity environments (≤1 m/s), consistent with ISO 7243 and JIS B 7922 requirements for WBGT instrumentation. Its sensor geometry, thermal mass, and ventilation design conform to Class 1.5 performance criteria per JIS B 7922-2017—indicating suitability for routine occupational monitoring where measurement uncertainty must remain within ±1.5 °C across the 15–40 °C WBGT range. The device meets electromagnetic compatibility (EMC) requirements per IEC 61326-1 and carries CE marking for conformity with EU health, safety, and environmental protection directives. Calibration traceability is maintained to NMI-Japan (National Metrology Institute of Japan) standards, and periodic verification follows JJF 1407–2013 procedures for WBGT index meters.

Software & Data Management

Measurement data is exported in CSV format via USB Type-C connection, enabling seamless integration with Excel, MATLAB, or enterprise EHS (Environmental, Health & Safety) platforms. No proprietary software installation is required—data appears as a removable storage device upon connection. Each record includes full metrological metadata: sensor IDs, calibration dates, operator ID fields (user-entered), and audit-ready timestamps. While the instrument itself does not implement FDA 21 CFR Part 11 electronic signature functionality, its structured, tamper-evident log file format supports GLP/GMP-aligned documentation practices when used in conjunction with validated laboratory information management systems (LIMS).

Applications

• Ongoing heat stress surveillance in manufacturing, utilities, mining, and logistics operations.
• Validation of engineering controls (e.g., ventilation upgrades, radiant barrier installations) and administrative interventions (e.g., work-rest cycles, acclimatization schedules).
• Compliance auditing for ISO 45001 occupational health and safety management systems.
• Field assessments during emergency response (wildfire recovery, disaster relief) and military training scenarios.
• Academic research on thermal comfort thresholds, climate adaptation strategies, and epidemiological correlation studies between WBGT exposure and heat-related morbidity.

FAQ

What is the recommended calibration interval for the WBGT-302?
Annual calibration is advised per JJF 1407–2013 and ISO/IEC 17025 requirements; however, users operating in extreme thermal cycling or high-dust environments should consider semi-annual verification.
Can the WBGT-302 be used for outdoor solar radiation assessment?
No—it does not measure solar irradiance or shortwave radiation; it assesses thermal load only. For solar heat gain analysis, pair with a pyranometer and apply correction models per ISO 7243 Annex B.
Is the black globe sensor interchangeable or field-replaceable?
The 50 mm black globe assembly is factory-integrated and non-user-serviceable; replacement requires return-to-factory service to preserve thermal inertia specifications and JIS Class 1.5 compliance.
Does the device support Bluetooth or Wi-Fi connectivity?
No—wireless transmission is intentionally omitted to ensure electromagnetic immunity in electrically noisy industrial zones and to maintain battery longevity.
How is relative humidity measured without condensation risk on the wet-bulb wick?
The wet-bulb sensor employs a sintered stainless-steel wick with controlled capillary action and active ventilation (≥2.5 m/s airflow) to sustain evaporative equilibrium while minimizing dew formation at high RH levels.