KNF FM 50 Diaphragm Liquid Metering Pump

Overview

The KNF FM 50 Diaphragm Liquid Metering Pump is a compact, precision-engineered OEM-grade fluid handling solution designed for accurate, repeatable liquid transfer in demanding laboratory and industrial environments. Based on positive displacement principle, the pump utilizes a reciprocating elastomeric diaphragm actuated by a brushless DC motor to generate controlled volumetric flow without internal lubrication or contamination risk. Its hermetically sealed architecture eliminates fluid contact with motor components, ensuring media purity—critical when handling neutral, aggressive, or biologically sensitive liquids. Engineered in Switzerland and built to ISO 9001-certified manufacturing standards, the FM 50 delivers stable performance across variable backpressure, temperature, and viscosity conditions—making it suitable for integration into analytical instrumentation, diagnostic platforms, and process-critical dosing systems where long-term reliability and regulatory compliance are non-negotiable.

Key Features

• Maintenance-free operation: No oil, no seals to replace, no scheduled servicing required over typical service life
• Self-priming capability up to 3 mH₂O suction lift, enabling flexible installation without auxiliary priming
• Dry-run safe design: Tolerates temporary operation without liquid present, preventing damage during startup or low-flow conditions
• Low-pulsation flow profile: Achieved via optimized diaphragm geometry and stroke control, minimizing pressure fluctuations in downstream sensing or detection modules
• Chemical resistance: Modular wetted path constructed from PP (pump head), EPDM or PTFE (diaphragm), and EPDM or FFKM (valve seats)—validated against common acids, bases, solvents, and sanitizing agents
• Digitally adjustable speed control: Enables precise flow rate tuning (0–100% of max 0.5 L/min) via analog voltage input or PWM signal, supporting closed-loop integration with PLCs or embedded controllers
• FDA-compliant and NSF/ANSI 61 certified materials: Meets regulatory requirements for food-contact, pharmaceutical, and potable water applications
• Compact footprint and lightweight construction (250 g): Facilitates space-constrained integration in portable analyzers, point-of-care devices, and benchtop automation systems

Sample Compatibility & Compliance

The FM 50 is validated for use with aqueous solutions, organic solvents, mild corrosives (e.g., dilute HCl, NaOH), disinfectants (e.g., hydrogen peroxide, quaternary ammonium compounds), and biological buffers. It is not intended for abrasive slurries, high-viscosity fluids (>500 mPa·s), or gases. All wetted materials comply with USP Class VI and EU Regulation (EC) No 1935/2004 for food contact. The pump meets IEC 61000-6-2 (immunity) and IEC 61000-6-4 (emissions) for electromagnetic compatibility. Its design supports GLP/GMP-aligned documentation packages—including material traceability records and factory calibration reports—upon request.

Software & Data Management

While the FM 50 operates as a standalone electromechanical device, its analog/PWM interface enables seamless integration into host system software stacks. When paired with KNF’s optional evaluation board or third-party DAQ hardware, users can log real-time motor current, duty cycle, and estimated flow trends for audit trails. For regulated environments, the pump supports 21 CFR Part 11-compliant electronic record generation when embedded within a validated instrument architecture that implements user authentication, audit logging, and data integrity controls. Firmware-upgradable motor drivers (available upon OEM agreement) allow future feature expansion including integrated flow feedback via external sensor fusion.

Applications

• Analytical instrumentation: Reagent delivery in spectrophotometers, ion chromatographs, and automated titrators
• Life sciences: Precise buffer exchange in microfluidic assay platforms and cell culture media handling
• Food & beverage QA/QC: Dosing of preservatives, flavorings, or cleaning-in-place (CIP) chemicals
• Medical diagnostics: Sample aspiration and reagent metering in immunoassay analyzers and hematology systems
• Semiconductor manufacturing: Ultra-pure chemical dosing in wafer cleaning and etch processes
• Fuel cell R&D: Humidification water management and electrolyte circulation in PEM stack test rigs
• Industrial cleaning systems: Controlled delivery of alkaline or acidic descaling agents

FAQ

Is the FM 50 suitable for sterile applications?

Yes—when configured with PTFE diaphragms and FFKM valves, and operated within validated cleaning and sterilization protocols (e.g., autoclaving of removable wetted parts or SIP-compatible housing options), it meets requirements for Class 100 cleanroom environments.
Can flow rate be calibrated traceably to national standards?

Yes—KNF provides NIST-traceable calibration certificates for individual units upon request; custom calibration curves (flow vs. PWM duty cycle) can be generated using gravimetric or timed-volume methods per ISO 5787.
What is the expected service life under continuous operation?

Rated for >20,000 hours MTBF at 50% load and ambient temperature (23°C); lifetime is extended significantly under intermittent or low-duty-cycle operation.
Does KNF offer application-specific customization?

Yes—OEM partners may request modifications including custom cable assemblies, modified mounting flanges, integrated pressure sensors, or firmware-tuned motor profiles aligned with specific fluid dynamics requirements.