OK Walk-in Constant Humidity & Temperature Chamber OK-STH-12.022m²

Overview

The OK Walk-in Constant Humidity & Temperature Chamber OK-STH-12.022m² is a large-volume, precision-engineered environmental test system designed exclusively for long-term, stable maintenance of fixed temperature and relative humidity setpoints. Unlike programmable or cycling chambers, this unit operates under strict constant-condition principles—complying with IEC 60068-2-78 and GB/T 2423.3 for the standardized “Test Cab: Damp Heat, Steady State” protocol. Its operational paradigm centers on thermal and hygric stability—not dynamic transitions—making it ideal for applications requiring uninterrupted exposure over hundreds or thousands of hours. The chamber’s architecture prioritizes spatial uniformity, control repeatability, and mechanical robustness for continuous unattended operation. It employs a dual-loop PID control strategy with independent temperature and humidity regulation channels, integrated with high-stability platinum resistance (PT100) sensors and capacitive RH transducers calibrated traceably to NIST-traceable standards. All internal surfaces are constructed from stainless steel (SUS304), and the insulation comprises high-density polyurethane foam (≥150 mm thickness, λ ≤ 0.022 W/m·K) to minimize thermal bridging and ensure low heat leakage under steady-state load.

Key Features

• Walk-in configuration with fully accessible interior (2000 × 3000 × 2000 mm working volume), enabling testing of large-scale assemblies, automotive components, medical devices, or batched consumer electronics.
• Dedicated constant-condition design: optimized refrigeration, heating, and humidification subsystems eliminate unnecessary power redundancy—reducing energy consumption and long-term maintenance overhead compared to cycling-capable units.
• Multi-stage refrigeration system with hermetic scroll compressors (Embraco or Bitzer, configurable per temperature range option), dry filter-separators, and copper-aluminum finned evaporators engineered for sustained low-load operation at target setpoints.
• Steam-based humidification system using industrial-grade stainless-steel boiler (pure steam output, <1 µS/cm conductivity), coupled with deionized water pretreatment via integrated RO + EDI purification module to prevent mineral deposition and ensure RH stability above 90% RH.
• Low-velocity, high-volume air distribution: centrifugal fans with EC motor drives deliver ≥12 air changes per hour through perforated aluminum ceiling diffusers and floor return grilles—validated to achieve ≤±3°C temperature uniformity and ≤±3% RH uniformity across the entire workspace per ISO 16750-4 Annex A calibration methodology.
• Industrial-grade controller (Siemens Desigo CC or Yokogawa UT570 series) featuring dual-setpoint PID algorithms, real-time deviation logging, and configurable alarm thresholds for temperature, humidity, door status, and safety interlocks.

Sample Compatibility & Compliance

The OK-STH-12.022m² accommodates heterogeneous sample types—including sealed enclosures, unpackaged PCBs, polymer composites, pharmaceutical packaging, and lithium-ion battery modules—without compromising environmental fidelity. Its chamber layout includes adjustable stainless-steel shelves, cable ports with silicone grommets (Φ50/Φ80 mm), and optional grounding terminals compliant with IEC 61000-4-2 ESD requirements. From a regulatory standpoint, the system supports GLP-compliant validation protocols (IQ/OQ/PQ), generates audit-ready electronic records aligned with FDA 21 CFR Part 11 requirements (when paired with optional electronic signature module), and meets structural safety criteria per EN 61000-6-2 (immunity) and EN 61000-6-4 (emissions). It is routinely deployed in laboratories accredited to ISO/IEC 17025 for environmental testing services, particularly where test plans explicitly reference IEC 60068-2-78, MIL-STD-810H Method 502.7, or IPC-9701A for moisture sensitivity level (MSL) preconditioning.

Software & Data Management

The embedded controller provides local HMI operation with 7-inch color touchscreen, multi-level password protection, and real-time trend visualization for up to four parameters (T, RH, dew point, elapsed time). Optional Ethernet/Wi-Fi connectivity enables remote monitoring via OK’s proprietary WebSCADA interface—supporting secure HTTPS access, Modbus TCP integration, and CSV export of time-stamped data at user-defined intervals (1 s to 60 min resolution). All logged data include metadata (operator ID, test ID, chamber serial number, sensor calibration dates) and are stored redundantly on both internal industrial SSD and external NAS via SMB/CIFS. Audit trails record every parameter change, manual override, alarm event, and calibration action—with immutable timestamps and user attribution—ensuring full traceability for GMP, ISO 9001, or AS9100 quality audits.

Applications

• Long-term storage stability assessment of active pharmaceutical ingredients (APIs), lyophilized biologics, and barrier-packaged medical devices per USP and ISO 11607-1.
• Accelerated aging studies of polymer-based insulators, adhesives, and conformal coatings under tropical-equivalent conditions (e.g., 40°C / 93% RH).
• Electrochemical validation of Li-ion battery cells and modules prior to thermal runaway testing (UN 38.3 Section 4.4).
• Material hygroscopicity and water vapor transmission rate (WVTR) benchmarking for flexible packaging films per ASTM F1249 and ISO 15106-3.
• Environmental stress screening (ESS) of avionics line-replaceable units (LRUs) per RTCA DO-160G Section 4.11 (Steady-State Damp Heat).
• Preconditioning of optical sensors and MEMS accelerometers prior to shock/vibration qualification per MIL-STD-810H.

FAQ

Does this chamber support temperature/humidity cycling or ramp profiles?
No. The OK-STH-12.022m² is engineered solely for steady-state operation. It lacks multi-segment programming, ramp-rate control, or condensation management features required for IEC 60068-2-30 (Test Db). For cycling applications, consider the OK-CTH series.
What is the recommended calibration interval for traceable compliance?
Annual field calibration is advised using NIST-traceable dry-well calibrators (temperature) and chilled-mirror hygrometers (humidity), with as-found/as-left reports retained per ISO/IEC 17025 Clause 6.6.
Can the chamber operate continuously for 1000+ hours without intervention?
Yes. Its compressor duty cycle, fan bearing lifetime (>50,000 h), and humidifier boiler maintenance schedule (every 6 months under continuous 95% RH operation) are all rated for uninterrupted 24/7 service.
Is third-party validation support available?
OK Instruments provides IQ/OQ documentation templates, on-site witness support, and certified calibration certificates issued by CNAS-accredited labs upon request.
How is humidity controlled at low temperatures (e.g., −40°C)?
At sub-zero setpoints, humidity control is disabled by default; the chamber operates in dry-cold mode. Optional low-temperature RH capability (down to −20°C at 10–30% RH) requires supplemental ultrasonic humidification and heated ducting—available as a factory-configured option.