MKN 85-2A Digital Dual-Directional Magnetic Stirrer with Integrated Heating and Temperature Control

Overview

The MKN 85-2A Digital Dual-Directional Magnetic Stirrer with Integrated Heating and Temperature Control is an engineered solution for precise, reproducible mixing and thermal conditioning of liquid samples in analytical, quality control, and research laboratory environments. It operates on the principle of magnetic coupling: a rotating permanent magnet array beneath the stainless-steel plate induces synchronous rotation of a magnetically responsive stir bar immersed in the sample vessel. Unlike gear-driven mechanical stirrers, this system eliminates shaft seals, reduces contamination risk, and ensures maintenance-free operation over extended duty cycles. The dual-directional capability—programmable clockwise and counterclockwise rotation sequences—enhances homogenization efficiency for viscous or heterogeneous suspensions where unidirectional agitation may induce vortex asymmetry or particle stratification. Integrated PID-controlled heating enables simultaneous stirring and temperature stabilization, supporting applications such as dissolution testing, buffer equilibration, reagent synthesis, and kinetic reaction monitoring under controlled thermal conditions.

Key Features

• Dual-directional stirring mode with programmable rotation direction switching—improves dispersion uniformity in colloidal suspensions, polymer solutions, and precipitate-containing mixtures.
• Digital PID temperature controller with ±0.5 °C accuracy across 25–100 °C range; real-time display via LED interface with overshoot suppression algorithm.
• Brushless DC motor drive delivering smooth, low-noise (<45 dB(A)) operation and extended service life—no carbon brushes to replace, no commutation sparking, minimal electromagnetic interference.
• Stainless-steel (AISI 304) top plate with chemical-resistant surface finish; optimized thermal conductivity for rapid heat transfer and even temperature distribution.
• Infinitely variable speed control (0–2400 rpm) with tachometric feedback; digital setpoint retention after power interruption.
• Integrated timer function (0–120 min) with audible end-of-cycle alert and automatic shutdown—supports unattended operation during standardized protocols.
• Compatibility with fluoropolymer-encapsulated stir bars (e.g., PTFE/SiO₂ composite), rated for continuous use up to 100 °C and resistant to strong acids, alkalis, and organic solvents.

Sample Compatibility & Compliance

The MKN 85-2A accommodates standard laboratory glassware including beakers (20–3000 mL), Erlenmeyer flasks, and sealed reaction vessels with non-magnetic lids (e.g., borosilicate glass, polypropylene). Its sealed-drive architecture allows safe operation inside fume hoods or inert-atmosphere gloveboxes. While not certified to IEC 61000-6-3 or UL 61010-1 as a standalone medical device, its electrical design follows CE-conformant safety practices for Class I laboratory equipment. The unit supports Good Laboratory Practice (GLP) workflows through repeatable parameter recall and time-stamped operational logging when paired with external data acquisition systems. It meets functional requirements referenced in ASTM D1720 (standard test method for viscosity of adhesives) and USP (dissolution apparatus calibration guidelines) for auxiliary thermal-mixing support.

Software & Data Management

The MKN 85-2A operates as a stand-alone instrument with embedded firmware—no proprietary software or driver installation required. All parameters (speed, temperature, timer) are configured via front-panel membrane keys and displayed on a dual-segment LED screen (rpm and °C). For laboratories requiring audit trails, the device can be integrated into supervisory control systems via optional RS-232 or 0–5 V analog output modules (sold separately), enabling timestamped parameter capture in LIMS or ELN platforms. Firmware supports GLP-compliant features including user-level access restriction (via password-protected setup mode) and configuration lockout during active runs—facilitating compliance with FDA 21 CFR Part 11 when used within validated processes.

Applications

• Preparation of homogeneous calibration standards and reference materials in environmental, pharmaceutical, and food testing labs.
• Accelerated solvent extraction (ASE) pre-conditioning and leachate equilibration prior to ICP-MS or HPLC analysis.
• Controlled-temperature titration setups where reagent stability depends on thermal consistency during mixing.
• Cell culture media warming and pH buffer equilibration without introducing shear stress from overhead stirrers.
• Small-scale polymerization reactions requiring sequential directional agitation to manage gelation kinetics.
• Dissolution profile development per USP Apparatus II (paddle) validation protocols, serving as auxiliary bath-mixing support.

FAQ

Does the MKN 85-2A support external temperature probe input for jacketed vessel control?
No—the built-in sensor measures plate surface temperature only. For jacketed reactor integration, an external temperature controller with relay output is recommended.
Can the stirrer maintain 100 °C while operating at maximum speed (2400 rpm)?
Yes—thermal and mechanical subsystems are independently regulated; full-speed operation is fully compatible across the entire temperature range.
Is the stainless-steel plate removable for cleaning or replacement?
No—the plate is permanently bonded to the heating element assembly; cleaning is performed in situ using non-abrasive ethanol wipes.
What stir bar dimensions are optimal for 2000 mL beaker operation at 1800 rpm?
A 40 × 8 mm elliptical PTFE-coated stir bar with embedded neodymium magnet provides optimal torque transfer and vortex stability at that scale and speed.
Does the timer function pause during temperature ramping?
No—the timer operates independently and begins counting upon activation, regardless of whether the unit is heating, holding, or cooling.