MKN 85-2 Temperature-Controlled Magnetic Stirrer
| Brand | MKN |
|---|---|
| Model | 85-2 |
| Power Supply | 220 V ±10%, 50 Hz ±2% |
| Max. Working Volume | 3000 mL |
| Speed Range | 0–2400 rpm (continuously variable) |
| Temperature Control Range | Ambient to 150 °C (digital PID temperature controller) |
| Heating Plate Material | Stainless Steel |
| Stir Bar Compatibility | Fluoropolymer-coated high-grade neodymium magnets |
| Optional Timer | 0–999 min (field-installable module) |
Overview
The MKN 85-2 Temperature-Controlled Magnetic Stirrer is an engineered solution for precise, simultaneous heating and agitation of liquid samples in research laboratories, quality control environments, and educational institutions. Based on the principle of magnetic coupling—where a rotating permanent magnet beneath the heating plate induces synchronous rotation of a magnetically responsive stir bar immersed in the sample—the instrument delivers consistent torque transfer without mechanical shaft penetration. This design eliminates contamination risk, enables operation under sealed or inert-atmosphere conditions (e.g., Schlenk lines or gloveboxes), and supports reproducible thermal and hydrodynamic profiles essential for kinetic studies, dissolution testing, buffer preparation, and reagent synthesis. Its stainless steel heating plate ensures uniform thermal distribution and long-term corrosion resistance against common solvents and aqueous media.
Key Features
- Brushless DC motor drive: Delivers low acoustic noise (<45 dB(A) at 1 m), extended service life, and stable rotational output across the full speed range without gear wear or carbon brush degradation.
- Digital PID temperature control: Integrated microprocessor-based regulation with ±0.5 °C accuracy over the 20–150 °C operating range; real-time display via 4-digit LED interface with overshoot suppression algorithm.
- Continuously variable speed adjustment: 0–2400 rpm range with fine-resolution rotary encoder input; maintains setpoint stability under load variations up to 3000 mL water-equivalent viscosity (≤10 mPa·s).
- Chemically resistant stir bar compatibility: Optimized for fluoropolymer-encapsulated neodymium stir bars rated for continuous operation at 150 °C and exposure to acids, bases, and organic solvents (e.g., HCl, NaOH, acetone, ethanol).
- Robust thermal and electrical safety architecture: Includes dual independent thermal cutoffs (bimetallic + electronic), ground-fault detection, and auto-shutdown on open-circuit heating element failure.
Sample Compatibility & Compliance
The MKN 85-2 accommodates standard laboratory glassware including beakers (50–2000 mL), Erlenmeyer flasks, and round-bottom flasks with flat bases. It supports ISO/IEC 17025-compliant method validation when paired with traceable calibration standards (e.g., NIST-traceable RTD probes for temperature verification, certified tachometers for speed audit). While not intrinsically rated for hazardous area use, its sealed electronics and non-sparking motor meet general-purpose lab safety requirements per IEC 61010-1:2010 Ed.3. The device is suitable for applications aligned with USP (Dissolution Apparatus Calibration), ASTM E2913 (Standard Guide for Magnetic Stirring), and GLP documentation workflows requiring equipment qualification (IQ/OQ).
Software & Data Management
The base unit operates as a standalone analog-digital hybrid system with no embedded firmware or network connectivity. For regulated environments requiring audit trails, optional RS-485 serial interface modules (sold separately) enable integration into LabVantage, Thermo Fisher SampleManager, or custom SCADA platforms via Modbus RTU protocol. All parameter settings—including speed setpoint, target temperature, and timer activation—are retained in non-volatile memory during power interruption. Manual logbooks or LIMS-integrated electronic records may capture operational metadata (start time, duration, final temperature, observed homogeneity) per FDA 21 CFR Part 11 guidance when used in GMP manufacturing support roles.
Applications
- Preparation of homogeneous buffer solutions and culture media in microbiology and molecular biology labs.
- Controlled heating and mixing during titration standardization, pH adjustment, and redox reaction monitoring.
- Dissolution profile development for pharmaceutical dosage forms under USP Apparatus 2 (paddle-over-disk) auxiliary configurations.
- Accelerated stability testing of emulsions and colloidal suspensions where thermal history and shear exposure must be documented.
- Teaching laboratory demonstrations of Arrhenius kinetics, heat transfer principles, and fluid dynamics fundamentals.
FAQ
Does the MKN 85-2 support external temperature probe feedback for jacketed vessel control?
No—temperature regulation is based solely on integrated plate-sensor measurement. External probe input requires third-party PID controllers.
What is the maximum viscosity this stirrer can handle at 150 °C?
Performance is optimized for Newtonian fluids ≤10 mPa·s at full volume; higher viscosities require reduced volume and lower speed settings.
Is the unit compliant with CE or UKCA marking requirements?
It meets EMC Directive 2014/30/EU and Low Voltage Directive 2014/35/EU; however, formal conformity assessment and marking are the responsibility of the EU/UK authorized representative.
Can the timer function be retrofitted to units originally supplied without it?
Yes—field-upgrade kits including hardware module and front-panel overlay are available from MKN’s authorized service partners.
What calibration documentation is provided with shipment?
A factory-issued certificate of conformance (CoC) is included; NIST-traceable calibration certificates require separate purchase and scheduled onsite verification.
