JingHong DK-320 / DK-320S Benchtop Water Bath Circulator (Heating-Only, Non-Circulating Configuration)

Overview

The JingHong DK-320 and DK-320S are precision-engineered benchtop water baths designed for stable, repeatable thermal conditioning of samples in academic, industrial, and R&D laboratories. These units operate on resistive heating principles, utilizing embedded stainless-steel-sheathed heating elements and a microprocessor-controlled PID algorithm to maintain setpoint accuracy within ±0.5 °C across the operational range of ambient +5 °C to 65 °C. Unlike recirculating or refrigerated bath systems, the DK-320 is a heating-only, non-circulating unit—ideal for applications where gentle, uniform convection-driven heat transfer suffices, such as enzyme incubation, sample equilibration, dissolution testing pre-conditioning, and reagent warming. The DK-320S variant introduces an integrated external circulation interface, enabling connection to auxiliary equipment (e.g., jacketed reactors or secondary baths) when controlled fluid transfer is required—without compromising intrinsic thermal stability.

Key Features

• 304 stainless steel inner tank and lid—resistant to corrosion from aqueous solutions, cleaning agents, and prolonged thermal cycling
• Microprocessor-based temperature controller with dual LED display: simultaneous readout of setpoint and real-time bath temperature
• PID auto-tuning function ensures rapid stabilization and minimal overshoot during setpoint changes
• 0.1 °C temperature resolution supports fine-grained protocol definition and documentation
• Compact footprint (450 × 195 × 255 mm) optimized for limited bench space without sacrificing usable bath volume (6.75 L)
• Over-temperature cut-off protection and dry-run safeguard prevent heater damage during low-fluid conditions
• Front-panel accessible calibration offset adjustment for traceable instrument verification per internal QA procedures

Sample Compatibility & Compliance

The DK-320/DK-320S accommodates standard laboratory vessels—including glass beakers (up to 1000 mL), test tubes, cuvettes, and small flasks—within its open-bath configuration. Its uniform thermal field (validated per ASTM E1112 for liquid bath uniformity) ensures consistent sample exposure across the working zone. While not certified to ISO/IEC 17025 or FDA 21 CFR Part 11 out-of-the-box, the unit’s deterministic PID behavior, digital logging capability (when paired with optional RS232/USB data interface modules), and adjustable calibration offset support integration into GLP- and GMP-regulated workflows. Users may implement procedural controls—including daily temperature verification using NIST-traceable thermometers—and document deviations per internal SOPs.

Software & Data Management

The base DK-320/DK-320S operates via standalone hardware control with no embedded software stack. However, optional communication modules (JingHong Model COM-DK-USB or COM-DK-RS232) enable serial connectivity to Windows-based PCs. Compatible with free third-party data acquisition tools (e.g., LabVIEW SignalExpress, Tera Term, or custom Python scripts using PySerial), these interfaces permit time-stamped temperature logging at user-defined intervals (1–60 s). Audit trails—including operator ID, setpoint changes, and duration of operation—can be generated externally to satisfy ALCOA+ data integrity requirements when combined with validated electronic lab notebook (ELN) systems.

Applications

• Pre-warming of culture media and enzymatic reagents prior to assay setup
• Thermal equilibration of calibration standards (e.g., viscosity reference oils, pH buffers)
• Controlled solubilization of temperature-sensitive compounds in pharmaceutical development
• Supporting ASTM D445 (kinematic viscosity) and ISO 3104 sample conditioning protocols
• Stabilizing optical components during spectrophotometric baseline measurements
• Assisting USP <797> compounding environment temperature management for non-sterile preparations

FAQ

Does the DK-320 include an internal circulation pump?
No—the standard DK-320 model is a non-circulating bath. Circulation requires external pumping equipment or upgrading to the DK-320S, which features a dedicated outlet port for optional external loop integration.
Can the temperature sensor be recalibrated by the end user?
Yes—via front-panel calibration offset adjustment (±9.9 °C range), allowing correction against a NIST-traceable reference thermometer per routine verification SOPs.
Is the unit suitable for oil bath operation?
Not recommended—its design, materials, and safety interlocks are validated exclusively for aqueous media. Use of oils may compromise seal integrity and thermal cutoff response.
What is the maximum recommended fill level?
To ensure optimal thermal uniformity and avoid overflow during expansion, maintain liquid level between 30 mm and 130 mm above the tank base—corresponding to approximately 4–6.5 L capacity.
Does the DK-320S support closed-loop external circulation with feedback control?
No—the external port provides passive flow output only; temperature regulation remains internal to the bath chamber. Closed-loop control requires integration with an external PID controller and flow sensor.