DRETOP LJF40-120 Low-Temperature Magnetic Stirring Circulating Bath

Overview

The DRETOP LJF40-120 Low-Temperature Magnetic Stirring Circulating Bath is an integrated thermal management system engineered for precision temperature control across extreme operating conditions. It combines high-efficiency refrigeration (down to −120 °C), electric heating (up to +100 °C), magnetic stirring, and closed-loop fluid circulation in a single benchtop unit. Unlike standalone chillers or external cooling systems, the LJF40-120 features an open bath reservoir with built-in magnetic drive, enabling direct immersion of reaction vessels—eliminating the need for jacketed reactors or secondary heat exchangers. Its thermodynamic architecture relies on a dual-mode refrigeration cycle utilizing variable-frequency compressors and optimized heat exchanger geometry to ensure rapid cooldown, stable setpoint maintenance, and minimal thermal gradient across the 40 L stainless steel tank. This design supports applications requiring both cryogenic kinetics and controlled endothermic/exothermic transitions—such as organometallic synthesis, superconducting material characterization, and low-temperature biostability assays—under reproducible, GLP-aligned operational conditions.

Key Features

• PID-based digital temperature controller with high-resolution Pt100 sensor feedback loop; typical setpoint accuracy ±0.1 °C within the −120 °C to +100 °C range
• Integrated brushless magnetic stirrer with adjustable speed (0–1200 rpm), compatible with standard PTFE-coated stir bars; enables uniform thermal distribution without mechanical seal leakage risks
• 40 L seamless 304 stainless steel reservoir with corrosion-resistant interior finish and reinforced thermal insulation
• High-capacity water-cooled condensing system rated for continuous duty at full load; compressor power modulated via inverter drive to match thermal demand
• RS485 serial interface supporting Modbus RTU protocol for integration into LabVIEW, MATLAB, or SCADA-based monitoring environments
• IP54-rated enclosure with industrial-grade electrical protection: overtemperature, low-level, phase-loss, pressure fault, and ground-fault detection with audible/visual alarms
• Dual-circuit circulation architecture—supports internal bath homogenization or external closed-loop delivery to auxiliary equipment (e.g., jacketed reactors, spectroscopy cells)

Sample Compatibility & Compliance

The LJF40-120 accommodates a wide range of heat transfer media—including aqueous glycol mixtures, ethanol, silicone oils, and specialized low-viscosity cryogenic fluids—selected per operational temperature window to prevent freezing, vapor lock, or thermal degradation. Its sealed stainless steel fluid path complies with ISO 8573-1:2010 (compressed air purity) and ASTM D1384 (coolant compatibility) guidelines for non-reactive fluid handling. All wetted components meet USP Class VI biocompatibility requirements, making the unit suitable for pharmaceutical process development under cGMP Annex 1 and FDA 21 CFR Part 11-compliant data logging configurations (when paired with validated software). The bath’s open-top geometry permits direct placement of glassware (e.g., round-bottom flasks up to 5 L), probe-based sensors, reflux condensers, and automated titration manifolds—facilitating seamless adaptation to synthetic chemistry, cryobiology, and materials science workflows.

Software & Data Management

Equipped with embedded firmware supporting real-time temperature logging at user-defined intervals (1 s to 60 min), the LJF40-120 records timestamped datasets to internal flash memory (≥1 million points) with automatic rollover. When connected via RS485 to a host PC running DRETOP’s optional ThermaLog Pro software, users gain access to graphical trend analysis, alarm history export (CSV/PDF), multi-channel overlay plots, and audit-trail-enabled user authentication—meeting ALCOA+ principles for data integrity. The system supports scheduled ramp-soak profiles (up to 10 segments), deviation alerts with configurable hysteresis, and remote firmware updates via secure HTTPS endpoint. For regulated environments, optional 21 CFR Part 11 compliance packages include electronic signatures, role-based access control, and immutable record archiving.

Applications

• Low-temperature organic synthesis (e.g., Grignard, Diels–Alder, lithiation reactions requiring sustained −30 °C to −78 °C conditions)
• Cryogenic testing of superconductors, piezoelectric ceramics, and battery electrolytes under thermal cycling stress
• Controlled-rate freezing of primary cell cultures, tissue samples, and mRNA-LNP formulations
• Stabilization of high-power laser diodes, CCD detectors, and NMR preamplifiers during spectral acquisition
• In-process temperature control for vacuum deposition systems, thin-film sputtering, and molecular beam epitaxy
• Calibration of thermocouples, RTDs, and infrared pyrometers across extended cryogenic ranges

FAQ

What types of heat transfer fluids are compatible with the LJF40-120 at −120 °C?
Ethanol, methanol, and specially formulated low-freezing-point glycol–water blends (e.g., Dowtherm J) are recommended. Silicone oils may be used above −60 °C; consult DRETOP’s Fluid Compatibility Matrix before selection.
Does the unit support external temperature feedback control?
Yes—via optional PT100 input port, enabling cascade control using an external probe placed directly in the reaction mixture.
Can the magnetic stirrer operate simultaneously with full-power refrigeration?
Yes. The stirrer motor is thermally isolated and rated for continuous operation across the entire temperature range, including at −120 °C.
Is the reservoir volume sufficient for submerging a 3-liter reactor flask?
With a 360 mm diameter opening and 40 L capacity, the bath accommodates standard 3 L round-bottom flasks when partially filled with coolant; optimal immersion depth requires ≥150 mm fluid level.
What safety certifications does the LJF40-120 hold?
CE-marked per EN 61000-6-3 (EMC) and EN 61010-1 (electrical safety); RoHS 2011/65/EU compliant; factory-tested per IEC 60068-2 environmental stress protocols.