BJBY BY-2003HT Direct-Reading Wet-and-Dry Bulb Thermohygrometer

Overview

The BJBY BY-2003HT Direct-Reading Wet-and-Dry Bulb Thermohygrometer is a portable, battery-powered handheld instrument engineered for simultaneous measurement of ambient temperature and relative humidity (RH) using the psychrometric principle. Unlike capacitive or resistive sensor-based hygrometers, the BY-2003HT implements a classic dual-sensor configuration—comprising a dry-bulb thermometer and a wet-bulb thermometer with a saturated wick—to determine RH via evaporative cooling dynamics. This method delivers inherent traceability to fundamental thermodynamic properties and eliminates reliance on polymer-based humidity sensors subject to long-term drift or chemical contamination. Designed for field-deployable operation, the device integrates precision platinum resistance temperature detectors (PRTDs) or high-stability thermistors calibrated per ISO/IEC 17025-accredited procedures, ensuring metrological integrity across its full operating range of −40°C to +60°C and 0–100% RH. Its compact form factor, low power consumption, and robust ABS housing make it suitable for unattended spot measurements in variable environmental conditions without external data loggers or PC interfaces.

Key Features

• True psychrometric measurement architecture—dry-bulb and wet-bulb temperature sensing enables direct calculation of RH without algorithmic compensation or factory-only calibration.
• User-accessible two-point calibration routine for both temperature and humidity channels, supporting periodic verification against NIST-traceable reference standards (e.g., saturated salt solutions or calibrated climate chambers).
• Segment-type LCD with integrated backlight ensures legibility under low-light industrial or outdoor conditions; large character height improves readability during occupational health surveys.
• Low-voltage detection circuitry provides visual warning prior to battery depletion, preventing data loss during extended monitoring sessions.
• High-resolution display outputs temperature and RH simultaneously with 0.1°C and 0.1% RH resolution—critical for compliance with OSHA 1910.95 (noise and thermal stress assessments) and ISO 7730 (moderate thermal environments).
• ABS polymer enclosure meets IP54-rated ingress protection against dust and water splashes, enabling reliable use in manufacturing floors, HVAC duct inspections, and warehouse quality audits.

Sample Compatibility & Compliance

The BY-2003HT is intended for gaseous phase ambient air measurement only; it is not rated for corrosive, explosive, or particulate-laden atmospheres without auxiliary filtration. It complies with general-purpose instrumentation safety requirements per IEC 61010-1:2010 (measurement category II, pollution degree 2). While not certified to specific medical or pharmaceutical regulatory frameworks (e.g., FDA 21 CFR Part 11 or EU Annex 11), its calibration traceability path and documented uncertainty budget support use in GLP-aligned environmental monitoring programs. The instrument satisfies performance criteria outlined in ASTM E337–22 (Standard Test Method for Measuring Humidity with a Sling Psychrometer) when operated per manufacturer’s procedural guidance—including proper ventilation (>3 m/s airflow over wet bulb), wick saturation protocol, and stabilization time (>90 s per reading).

Software & Data Management

The BY-2003HT operates as a standalone, non-networked instrument with no embedded memory or digital communication ports (e.g., USB, Bluetooth, RS-232). All measurements are displayed in real time and must be manually recorded. This design prioritizes operational simplicity, electromagnetic immunity, and long-term stability—avoiding firmware vulnerabilities or software obsolescence risks associated with connected devices. For laboratories requiring audit-ready documentation, users may integrate readings into LIMS or ELN platforms via manual entry or optical character recognition (OCR) workflows. Calibration records—including date, standard used, deviation values, and technician signature—should be retained per ISO/IEC 17025 clause 7.7 to demonstrate ongoing measurement validity.

Applications

• Occupational hygiene assessments per ACGIH TLVs® for heat stress indices (WBGT estimation using dry/wet bulb inputs).
• Pre-shipment environmental verification in cold-chain logistics and pharmaceutical distribution centers.
• Baseline indoor air quality (IAQ) surveys compliant with ASHRAE Standard 62.1 ventilation requirements.
• Educational demonstrations of psychrometric chart interpretation and moisture content calculations in HVAC engineering curricula.
• Periodic validation of incubator, stability chamber, or cleanroom environmental monitoring systems (as a secondary reference).
• Field verification of building envelope performance during commissioning of vapor barriers and insulation systems.

FAQ

Does the BY-2003HT require regular recalibration?

Yes—psychrometric instruments demand periodic verification due to wick degradation, sensor aging, and ambient pressure effects. Annual calibration against traceable standards is recommended; more frequent checks are advised if used in high-dust or high-salt environments.
Can this unit measure dew point directly?

No—it displays dry-bulb and wet-bulb temperatures only. Dew point must be calculated externally using published psychrometric equations or online calculators (e.g., NOAA or NIST tools).
Is the wet-bulb wick replaceable?

Yes—the cotton or linen wick is user-serviceable and should be replaced before each measurement session if contaminated or desiccated; replacement kits are available from authorized BJBY distributors.
What is the minimum airflow required for accurate wet-bulb readings?

A minimum air velocity of 3 m/s across the wet bulb surface is required per ASTM E337–22; natural convection yields significant error—use with a mechanical sling or fan-assisted probe for field accuracy.
Does the device compensate for barometric pressure changes?

No—this model assumes standard atmospheric pressure (101.325 kPa). For altitudes above 500 m or controlled-pressure environments, apply correction factors using the Goff–Gratch equation or consult NIST SP 960-15.