Techne RB-5A Refrigerated Circulating Bath

Overview

The Techne RB-5A Refrigerated Circulating Bath is a precision-engineered temperature control system designed for laboratory applications requiring stable, reproducible thermal environments across a broad operational range. Utilizing a hermetically sealed, air-cooled refrigeration circuit with R134a refrigerant, the RB-5A delivers active cooling and heating via a dual-mode PID-controlled thermoelectric or resistive heater assembly—enabling continuous setpoint regulation from −20 °C to +100 °C. Its circulation architecture employs a magnetically coupled centrifugal pump to minimize vibration transfer and ensure laminar, pulse-free fluid delivery to external devices such as viscometers, spectrophotometer jackets, calorimeters, or reaction blocks. The bath’s stainless steel reservoir and corrosion-resistant internal plumbing are compatible with aqueous solutions, glycol-water mixtures, and alcohol-based heat transfer fluids—supporting extended low-temperature operation down to −20 °C under standard ambient conditions (20 °C), and lower when using optimized coolant blends.

Key Features

• Integrated refrigeration system with high-efficiency compressor and optimized condenser design for stable sub-ambient operation
• Precision digital PID temperature controller with ±0.05 °C stability (at setpoint) and 0.1 °C resolution
• Programmable ramp-soak profiles and remote analog/digital interface options (0–10 V or 4–20 mA) for integration into automated workflows
• Stainless steel reservoir (192 × 151 × 200 mm) with removable cover and bridge-style mounting plate for secure accessory fixation
• Adjustable flow output (20 L/min pressure / 15 L/min suction) with calibrated bypass valve to maintain consistent head pressure across variable external load impedances
• Over-temperature, low-level, and dry-run safety interlocks compliant with IEC 61010-1:2010 for Class II laboratory equipment

Sample Compatibility & Compliance

The RB-5A accommodates immersion of probes, sensors, reactors, and analytical instrumentation requiring precise thermal coupling. Its open-bath configuration supports direct sample placement or connection to external jacketed vessels via standardized ½″ BSP threaded ports. Fluid compatibility extends to water, 30–50% aqueous glycol solutions, and ethanol/water mixtures—validated for long-term use at temperatures ≥ −30 °C. All electrical and mechanical designs conform to CE marking requirements under the EU Machinery Directive 2006/42/EC and Low Voltage Directive 2014/35/EU. The unit meets essential performance criteria outlined in ASTM E2777-11 (Standard Practice for Calibration of Thermal Baths) and supports GLP-compliant documentation through optional audit-trail-enabled controllers (FDA 21 CFR Part 11 ready with appropriate software licensing).

Software & Data Management

While the base RB-5A operates via front-panel keypad and LED display, optional Techne Link™ software enables PC-based monitoring, real-time graphing, and data logging via RS232 or USB virtual COM port. Logged parameters include setpoint, actual bath temperature, pump status, compressor duty cycle, and error codes—all timestamped with millisecond resolution. Export formats include CSV and XML for downstream analysis in MATLAB, LabVIEW, or LIMS platforms. For regulated environments, the optional “Secure Control” firmware module provides user role-based access levels, electronic signature capture, and immutable event logs meeting ALCOA+ data integrity principles.

Applications

• Calibration of temperature-sensitive metrology tools including platinum resistance thermometers (PRTs) and thermocouples per ISO/IEC 17025 requirements
• Thermal conditioning of optical components during interferometric alignment or spectroscopic wavelength validation
• Stabilization of HPLC column ovens and detector cells to reduce baseline drift in quantitative chromatography
• Controlled-rate cooling/heating of polymer samples during DSC pre-conditioning or rheological preshearing protocols
• Environmental simulation for accelerated aging studies of adhesives, coatings, and encapsulants per ASTM D7842

FAQ

What coolant mixture is recommended to achieve −20 °C operation?
A 40% deionized water / 40% propylene glycol / 20% ethanol (v/v/v) mixture is validated for reliable −20 °C performance at ambient 20 °C; viscosity and thermal conductivity must be verified for extended use.
Can the RB-5A be used with external recirculation loops exceeding 5 m in length?
Yes—provided total hydraulic resistance remains below 1.2 bar; Techne recommends installing an inline pressure gauge and flow meter to verify minimum 12 L/min throughput at the farthest outlet.
Is the unit suitable for GMP-regulated QC laboratories?
When equipped with Secure Control firmware and paired with IQ/OQ documentation packages (available separately), the RB-5A satisfies temperature uniformity, accuracy, and traceability requirements for USP and Annex 11 compliance.
Does the RB-5A support external temperature feedback from a probe placed in the sample rather than the bath?
Yes—the optional “External Sensor Mode” allows the controller to regulate based on input from a PT100 probe immersed directly in the process fluid, enabling true sample-centric thermal control.
What maintenance intervals are specified for the refrigeration system?
Compressor oil and refrigerant charge require verification every 24 months under continuous operation; filter-drier replacement is recommended annually or after any system breach.