YiHeng LHS-250HC-I / LHS-250HC-II Temperature and Humidity Controlled Chamber

Overview

The YiHeng LHS-250HC-I and LHS-250HC-II are upright, microprocessor-controlled environmental test chambers engineered for precise, long-term stabilization of temperature and relative humidity (RH) across laboratory, quality assurance, and materials testing applications. These chambers operate on a dual-loop TMHM (Temperature and Humidity Mutual Harmonization) control principle—where independent refrigeration, heating, and humidification subsystems dynamically interact to minimize thermal lag and moisture overshoot. Unlike single-loop PID systems, the TMHM architecture ensures high reproducibility in cyclic or static conditioning protocols, particularly critical for accelerated aging studies (e.g., IEC 60068-2-30, ISO 4892-2), stability testing per ICH Q1 guidelines, and hygroscopic material evaluation. The chamber’s structural integrity is reinforced by a double-wall insulated cabinet with CFC-free polyurethane foam (ODP = 0), aligning with EU F-Gas Regulation (EU No 517/2014) and China’s HCFC Phase-Out Management Plan.

Key Features

• Corrosion-resistant mirror-finish stainless steel interior (SUS304), featuring radius-rounded corners and adjustable stainless steel shelving for optimal airflow distribution and cleaning efficiency.
• High-accuracy imported capacitive humidity sensor (±1.5% RH typical accuracy at 25°C/50% RH) coupled with platinum resistance thermometers (Pt100, Class A) for real-time feedback in the control loop.
• Dual-stage refrigeration system using environmentally compliant R134a refrigerant, integrated with an imported hermetic compressor and oversized condenser for stable low-temperature performance down to –10°C.
• Independent over-temperature cut-off circuit with mechanical thermostat backup—compliant with IEC 61000-4-2 ESD immunity and EN 61010-1 safety requirements for lab equipment.
• Standard 25 mm diameter access port on left sidewall (sealable with silicone plug), enabling external probe insertion, gas purging, or sensor calibration without compromising chamber integrity.
• Front-panel LCD interface with real-time display of setpoint/actual values, trend graph (last 72 h), and event log (start/stop, alarm triggers, parameter changes).

Sample Compatibility & Compliance

The LHS-250HC series accommodates diverse sample geometries up to 600 × 500 × 830 mm internal volume, supporting standard ISO/IEC 17025-compliant validation protocols including IQ/OQ/PQ documentation packages. It meets essential regulatory prerequisites for GLP and GMP environments: traceable calibration paths (NIST-traceable reference sensors available upon request), audit-ready operation logs, and configurable alarm thresholds with latching behavior. Humidity control performance conforms to ASTM E1823–22 Annex A1 for RH uniformity assessment; temperature stability complies with ISO 16750-4:2018 (automotive component testing) and GB/T 10586–2018 (Chinese national standard for environmental chambers). Optional validation support includes 9-point temperature/humidity mapping reports and uncertainty budgets per EURACHEM/CITAC Guide.

Software & Data Management

An optional RS485 serial interface (Modbus RTU protocol) enables integration with SCADA systems, LIMS, or centralized monitoring platforms. When paired with YiHeng’s optional data logger module, users can export timestamped CSV files containing temperature, humidity, alarm status, and runtime diagnostics—structured for direct import into statistical process control (SPC) software such as Minitab or JMP. All logged data include ISO 8601 timestamps, instrument ID, and operator ID fields—supporting 21 CFR Part 11 compliance when deployed with validated electronic signature and audit trail configuration. Printer output (thermal or dot-matrix, optional) provides hard-copy records meeting FDA inspection expectations for raw environmental data archiving.

Applications

• Pharmaceutical stability testing under ICH Q5C conditions (25°C/60% RH, 30°C/65% RH, 40°C/75% RH)
• Electronics reliability screening per JEDEC JESD22-A110 (damp heat test) and MIL-STD-810H Method 507.6
• Polymer and composite material hygrothermal aging per ASTM D5229/D5229M and ISO 11357-4
• Seed germination and plant tissue culture preconditioning (controlled dormancy break)
• Calibration lab environmental conditioning for weighing rooms and dimensional metrology suites
• Adhesive and coating curing profile development under variable RH regimes

FAQ

What is the difference between LHS-250HC-I and LHS-250HC-II models?

The LHS-250HC-I offers a temperature range of –5°C to 80°C and humidity range of 40–85% RH, while the LHS-250HC-II extends low-temperature capability to –10°C and supports higher humidity up to 95% RH—optimized for stringent tropical or freeze-thaw cycling protocols.
Is third-party calibration certification available?

Yes. YiHeng provides optional factory calibration certificates traceable to CNAS-accredited laboratories (ISO/IEC 17025), including as-found/as-left data and measurement uncertainty statements.
Can the chamber be validated for GxP use?

Absolutely. Full IQ/OQ documentation templates, installation checklists, and operational test scripts are supplied. PQ execution support—including sensor placement rationale and acceptance criteria aligned with WHO TRS 992 Annex 6—is available via technical consultation.
Does the unit support remote monitoring via Ethernet or Wi-Fi?

The base model uses RS485. For Ethernet/Wi-Fi connectivity, a field-installable communication gateway (YiHeng NET-Link Pro) is offered as an accessory, enabling secure HTTPS-based web interface and SNMP v3 alerting.
What maintenance intervals are recommended?

Compressor oil and refrigerant levels should be verified annually; humidity sensor recalibration is advised every 12 months or after 2000 hours of active humidification duty. Full preventive maintenance (filter replacement, door seal inspection, condensate drain flush) is scheduled every 18 months.