ISMATEC ISM935 Low-Flow, High-Precision Multi-Channel Peristaltic Pump

Overview

The ISMATEC ISM935 is a low-flow, high-precision multi-channel peristaltic pump engineered for applications demanding exceptional volumetric accuracy, long-term stability, and minimal pulsation at ultra-low flow rates. Based on positive displacement peristaltic actuation—where fluid is transported through flexible tubing compressed sequentially by rotating stainless steel rollers—the ISM935 achieves reproducible flow control without internal valves, seals, or wetted moving parts. Its planetary gear-driven 8-roller head ensures smooth torque transmission and consistent occlusion across all operating speeds, minimizing mechanical wear and enabling precise regulation down to 0.0004 mL/min per channel. Designed for integration into analytical workflows—including HPLC sample introduction, microfluidic reagent delivery, cell culture media perfusion, and environmental monitoring systems—the ISM935 operates within a calibrated speed range of 0.11–11.25 rpm, optimized for compatibility with standard Tygon® tubing (ID 0.13–3.17 mm). All flow specifications are validated using deionized water at 22 °C under zero differential pressure conditions, in accordance with ISO 8536-4 and ASTM D4707 for peristaltic pump performance characterization.

Key Features

• Eight-stainless-steel-roller head driven by a precision planetary gear motor, delivering uniform compression and extended tubing life
• Dual-mode LED display: Mode A shows rotational speed (rpm or % of maximum); Mode B simultaneously displays real-time flow rate and rpm
• Click’n’go™ pump head mechanism enables tool-free, repeatable tubing installation with automatic occlusion calibration—ensuring inter-operator reproducibility
• Reversible pump head orientation: forward mounting reduces pulsation amplitude; reverse mounting increases backpressure tolerance up to 1.5 bar (dependent on tubing ID and wall thickness)
• MAX key functionality allows temporary speed override for priming or line flushing without altering stored program parameters
• Full analog I/O suite: programmable 0–5 VDC / 0–10 VDC / 0–20 mA / 4–20 mA inputs for speed control; analog output for real-time rpm monitoring
• RS-232 serial interface (DB9 male) supports full command-set control—including start/stop, direction reversal, volume dispensing, and status interrogation—via host PC or PLC
• TTL-compatible contact closure (DB15 female) enables external triggering of start/stop, direction, and auto-start functions; optional footswitch support via 3-pin DIN connector

Sample Compatibility & Compliance

The ISM935 accommodates a broad range of chemically resistant, USP Class VI-certified tubing materials—including Tygon® STR-3603, R-3607, PharMed® BPT, and Santoprene®—enabling safe handling of aqueous buffers, organic solvents, acids, and biological fluids. Tubing selection is governed by inner diameter (0.13–3.17 mm), wall thickness, and durometer, with flow rate tables provided for each configuration under standardized test conditions. The pump complies with IEC 61000-6-2 (immunity) and IEC 61000-6-4 (emissions), carries CE marking for EMC and LVD directives, and meets RoHS 2011/65/EU requirements. While not intrinsically rated for hazardous locations, its design supports integration into GLP- and GMP-regulated environments when paired with audit-trail-capable software and electronic log generation (e.g., via RS-232 timestamped command logging).

Software & Data Management

Although the ISM935 operates autonomously via front-panel controls, its RS-232 interface permits seamless integration with third-party laboratory automation platforms (e.g., LabVIEW, Python-based control scripts, or SCADA systems). Command protocols follow ASCII-based syntax with CR/LF termination, supporting asynchronous communication at configurable baud rates (9600–115200 bps). Critical operational parameters—including setpoint rpm, elapsed time, dispensed volume, and error codes—are accessible via query commands, facilitating automated data capture and traceability. When deployed in regulated settings, users may implement 21 CFR Part 11-compliant electronic signatures and audit trails through external middleware that logs all remote commands, timestamps, and user identifiers—ensuring alignment with FDA expectations for instrument control system validation.

Applications

• Continuous infusion in organ-on-chip and microphysiological systems requiring stable sub-μL/min delivery
• Automated reagent addition in spectrophotometric and fluorometric assays where pulse-induced signal noise must be minimized
• Calibration standard delivery for ICP-MS and IC systems where flow consistency directly impacts detection limit stability
• Low-volume solvent gradient formation in preparative chromatography and affinity purification setups
• Environmental water sampling stations integrating with pH, conductivity, and turbidity sensors for synchronized multi-analyte profiling
• Cell therapy manufacturing workflows involving gentle media exchange and cytokine dosing under aseptic conditions

FAQ

What tubing sizes are compatible with the ISM935?
The ISM935 supports Tygon® STR-3603/R-3607 tubing with inner diameters ranging from 0.13 mm to 3.17 mm. Specific flow rates per channel are documented for each size under zero-backpressure, 22 °C water conditions.
Can the ISM935 be used in GMP environments?
Yes—when integrated with validated software for command logging, user access control, and electronic signature enforcement, the ISM935 satisfies core instrumentation requirements for GMP process control and analytical method transfer.
Does the pump support drip-free dispensing?
Yes—its programmable “no-drip” mode executes a controlled reverse aspiration step after dispensing to eliminate post-dispense droplet formation.
How is flow rate accuracy verified?
Accuracy is determined gravimetrically per ISO 8536-4 using calibrated analytical balances and temperature-controlled water, with repeatability tested over ≥10 consecutive cycles at multiple setpoints across the full speed range.
Is firmware upgrade capability available?
Firmware updates are performed via RS-232 using manufacturer-provided utilities; version history and release notes are supplied with each update package for change control documentation.