VELP MST Digital Magnetic Stirrer

Overview

The VELP MST Digital Magnetic Stirrer is an engineered solution for precise, reproducible, and unattended liquid mixing in analytical, microbiological, biochemical, and environmental laboratories. Based on the principle of magnetic coupling—where a rotating permanent magnet beneath the work surface induces rotation of a magnetic stir bar immersed in the sample—the MST Digital delivers consistent torque transfer without mechanical contact, eliminating contamination risk and wear associated with shaft-driven systems. Its core architecture integrates a brushless DC motor and proprietary SpeedServo™ closed-loop speed regulation technology, enabling real-time rotational feedback and dynamic compensation for viscosity fluctuations during prolonged stirring. Designed for ISO/IEC 17025-compliant environments, the unit supports GLP-aligned workflows through traceable speed settings, programmable timing, and stable thermal management—critical for BOD incubation, enzyme kinetics, titration prep, and microbial culture maintenance.

Key Features

• SpeedServo™ Closed-Loop Control: Maintains set speed within ±2% deviation across load changes (e.g., from water to glycerol-based solutions), ensuring process repeatability in multi-step protocols.
• Digital LED Interface: High-contrast display shows real-time rpm and timer countdown; intuitive rotary encoder allows tactile, glove-compatible parameter adjustment.
• Programmable Auto-Reverse Mode: Alternates clockwise/counterclockwise rotation at user-defined intervals (1–120 min) to disrupt boundary layers and improve homogenization in viscous or particulate-laden samples.
• Low-Heat Brushless Motor: Engineered for continuous operation (>8 h) without thermal drift; surface temperature rise remains <3 K above ambient under full-load conditions at 1500 rpm.
• Chemically Inert Platform: White polymer housing resists corrosion from common solvents (e.g., ethanol, acetone, dilute acids/bases) and enables visual detection of precipitates or colorimetric endpoints.
• Thermostatic Compatibility: Integrated Peltier-based temperature control (5–40 °C) operates independently of stirring function, supporting temperature-sensitive assays such as PCR reagent prep or cold-chain sample conditioning.

Sample Compatibility & Compliance

The MST Digital accommodates standard laboratory glassware up to 5 L capacity—including Erlenmeyer flasks, beakers, and serum bottles—with optimal performance verified using ASTM D2196-compliant viscosity standards. Its non-magnetic platform ensures compatibility with ferromagnetic stir bars (e.g., PTFE-coated, AlNiCo, or SmCo variants) and eliminates interference with nearby electronic instrumentation. The device conforms to IEC 61010-1:2010 safety requirements for electrical equipment used in laboratory environments and carries CE marking under EU Directive 2014/30/EU (EMC) and 2014/35/EU (LVD). It supports audit-ready documentation per FDA 21 CFR Part 11 when integrated with validated LIMS or ELN platforms via optional RS-232 output.

Software & Data Management

While standalone operation requires no software, the MST Digital features an RS-232 serial interface (optional cable available) for integration into centralized lab automation systems. When connected, it transmits timestamped operational logs—including start/stop events, speed setpoints, actual rpm averages (sampled at 10 Hz), and temperature readings—to external controllers or data acquisition software. This enables compliance with ALCOA+ principles (Attributable, Legible, Contemporaneous, Original, Accurate) for QA/QC records. No proprietary drivers are required; ASCII protocol documentation is provided for custom SCADA or LabVIEW implementation.

Applications

• Preparation of standardized microbial growth media (ISO 7218, USP <61>) with uniform nutrient dispersion.
• BOD5 incubation per APHA Standard Methods 5210B, where consistent low-shear mixing prevents oxygen depletion gradients.
• pH and redox titrations requiring precise, vibration-free agitation during endpoint detection.
• Extraction protocols in environmental analysis (e.g., EPA Method 3510C) involving heterogeneous aqueous-organic phases.
• Cell suspension maintenance in primary culture workflows, minimizing shear-induced apoptosis.
• Reagent blending for ELISA and lateral flow assay development under controlled thermal conditions.

FAQ

Does the MST Digital support external temperature probes for closed-loop bath control?
No—the built-in Peltier module regulates platform surface temperature only; external probe integration is not supported.
What stir bar sizes are recommended for 5 L vessels?
For optimal torque transfer at high viscosity, use 80–100 mm elliptical or cross-shaped stir bars with ≥5 mm diameter and PTFE or glass coating.
Is the unit suitable for use inside CO₂ incubators?
Not recommended—operating temperature range (5–40 °C) and humidity tolerance (max. 80% RH non-condensing) do not meet typical incubator environmental specifications.
Can the auto-reverse interval be disabled?
Yes—reverse mode is fully optional; users may operate in continuous unidirectional mode via front-panel selection.
How is calibration verified for speed accuracy?
VELP provides factory calibration certificates traceable to NIST standards; end-users may verify rpm accuracy using a handheld optical tachometer aligned with the stir bar’s reflective marker.