Masterflex L/S Four-Channel Digital Dispensing Peristaltic Pump

Overview

The Masterflex L/S Four-Channel Digital Dispensing Peristaltic Pump (Model 77921-85) is an engineered solution for high-precision, multi-channel liquid handling in regulated and research-intensive laboratory environments. Based on the proven peristaltic principle—where fluid containment is achieved solely by occlusion of elastomeric tubing within a rotating roller assembly—the pump eliminates fluid-path contamination and enables rapid, tool-free tubing changeover. Designed specifically for dispensing applications requiring synchronized, repeatable volume delivery across four independent channels, this unit integrates a brushless DC motor drive with real-time speed feedback control to ensure long-term stability and minimal drift. Its architecture supports continuous-duty operation at rated load, making it suitable for extended unattended protocols in bioprocessing, analytical sample preparation, and quality control workflows.

Key Features

• Four independent L/S-series pump heads with six-roller geometry—reducing pulsation amplitude by up to 40% compared to standard two-roller configurations, thereby improving volumetric consistency during low-flow dispensing (e.g., <1 mL/min).
• Digital dispense programming interface allowing precise definition of volume per dispense, number of repeats, inter-dispense delay, and total cycle count—enabling fully automated serial dilution, reagent addition, or media fill sequences.
• Brushless DC motor (1/10 hp) with closed-loop tachometer feedback ensures ±0.1% speed regulation across the full 0.1–600 rpm range, critical for maintaining flow linearity under variable backpressure conditions.
• Front-panel membrane keypad with password-enabled lock function prevents inadvertent parameter changes during active operation—a requirement in GLP-compliant laboratories.
• DB25 female port supporting TTL-level remote start/stop, direction control, and analog speed modulation via external PLC or PC-based automation systems (e.g., LabVIEW, Python with NI DAQ).
• IP33-rated enclosure provides protection against vertically falling droplets and solid objects ≥2.5 mm—suitable for benchtop use in ISO Class 7 cleanrooms or QC labs with controlled humidity.

Sample Compatibility & Compliance

The pump is compatible exclusively with Masterflex L/S-series silicone tubing, including the BioPharm Plus platinum-cured formulation (L/S 13, 14, 16), which meets USP Class VI, ISO 10993-5, and EP 3.2.9 biocompatibility standards. This tubing exhibits low extractables, consistent durometer (Shore A 50 ±2), and minimal memory effect—ensuring reproducible flow profiles over >1,000 hours of continuous operation. The system supports tubing sizes from L/S 13 (1.6 mm ID) to L/S 16 (2.4 mm ID), enabling dynamic flow range adaptation without hardware modification. While the pump itself does not carry CE or UL certification as a standalone device, its power supply complies with IEC 61000-3-2 harmonic emission limits and operates within safety extra-low voltage (SELV) boundaries when used with approved Masterflex AC adapters.

Software & Data Management

This model operates as a stand-alone instrument without proprietary software dependency. All dispense parameters are stored in non-volatile memory and persist through power cycling. For integration into electronic lab notebooks (ELN) or LIMS, the DB25 interface allows ASCII command protocol communication (e.g., “SPD=320” to set speed) with timestamped status reporting. When deployed in FDA-regulated environments, users may configure external data loggers to record speed, runtime, and dispense count with audit-trail capability compliant with 21 CFR Part 11 requirements—provided the logging system implements user authentication, electronic signatures, and immutable storage.

Applications

• Automated buffer and reagent dispensing in HPLC and UPLC system priming and method development.
• Synchronized multi-well plate filling for ELISA, cell culture media preparation, and microbial assay setup.
• Continuous feed of pH-adjusting agents or titrants in bioreactor perfusion systems.
• Low-shear transfer of shear-sensitive biologics—including monoclonal antibodies and viral vectors—where metallic wetted parts or check valves would pose aggregation or adsorption risks.
• Calibration standard delivery in gravimetric flow verification setups per ISO 4064-2.

FAQ

What tubing sizes are supported out-of-the-box with the included pump head?
The standard L/S four-channel pump head accommodates L/S 13 (1.6 mm ID), L/S 14 (2.4 mm ID), and L/S 16 (3.2 mm ID) tubing. The shipped kit includes eight lengths of BioPharm Plus L/S 16 tubing (part #16-16).

Can the pump be integrated into a SCADA or MES environment?
Yes—via the DB25 interface using Modbus RTU over RS-485 (with optional converter) or discrete I/O signals for run/stop and fault indication. Masterflex provides pinout documentation and ASCII command reference for custom integration.

Is tubing lifetime validated under continuous operation?
Under nominal load (300 rpm, L/S 16 tubing, water at 25°C), typical service life exceeds 1,200 hours before flow deviation exceeds ±2%. Lifetime varies with fluid chemistry, pressure, and temperature; validation protocols should follow ASTM D412 for tensile retention testing.

Does the drive support analog speed input?
Yes—the DB25 connector includes pins for 0–10 VDC analog speed command input, scalable to the full 0.1–600 rpm range with 0.1 rpm resolution.