Cole-Parmer® Model 32936-42 Dual-Valve Bidirectional Mass Flow Controller
| Brand | Cole-Parmer |
|---|---|
| Origin | USA |
| Type | Differential Pressure-Based Mass Flow Controller |
| Model | 32936-42 |
| Gas Compatibility | Pre-calibrated for 98 pure and mixed gases |
| Flow Range | 2.5 mL/min to 50 L/min |
| Response Time | 50–100 ms |
| Output Signals | 0–5 V analog, RS-232 digital |
| Valve Configuration | Dual proportional solenoid valves (normally closed) |
| Operating Modes | Mass flow control under pressure or vacuum, bidirectional flow measurement, integrated pressure & temperature compensation |
| Power Supply | Included universal AC adapter |
| Communication Cable | Included |
Overview
The Cole-Parmer® Model 32936-42 Dual-Valve Bidirectional Mass Flow Controller is an engineered solution for precise, real-time regulation and measurement of gas mass flow in both forward and reverse directions. Based on differential pressure sensing with integrated thermal mass flow transduction, this controller employs two independently actuated proportional solenoid valves—configured in a normally closed architecture—to enable stable, high-fidelity control across a wide dynamic range (2.5 mL/min to 50 L/min). Unlike single-valve designs, the dual-valve topology allows simultaneous upstream and downstream pressure management, supporting operation under pressurized supply, vacuum draw, or closed-volume equilibration. The device delivers calibrated accuracy for 98 pre-characterized gases—including corrosive species such as Cl₂, NH₃, and HCl—without requiring user recalibration, leveraging NIST-traceable gas-specific calibration coefficients stored in non-volatile memory.
Key Features
- Bidirectional flow capability: Measures and controls mass and volumetric flow in both directions with identical precision and repeatability.
- Multi-gas support: Factory-calibrated for 98 pure and binary/mixed gases; calibration data embedded per gas ID for automatic scaling during selection.
- Sub-100 ms dynamic response: Achieves full-scale setpoint tracking within 50–100 milliseconds, enabling integration into fast-cycling process loops and feedback-controlled reactors.
- Dual-mode operation: Supports mass flow regulation under positive pressure (upstream source) or vacuum-driven flow (downstream sink), with automatic mode detection.
- Integrated environmental compensation: Onboard temperature and absolute pressure sensors enable real-time correction of flow readings per ISO 14111 and ASTM D7213 standards.
- Flexible I/O interface: Analog output (0–5 V DC, linear with mass flow) and ASCII-based RS-232 serial communication (9600 baud, no parity) for PLC, SCADA, or LabVIEW integration.
- Low ΔP design option: Available with ultra-low pressure drop configuration (<0.5 psi at full scale) for sensitive applications including microreactors and gas chromatography carrier flow control.
Sample Compatibility & Compliance
The Model 32936-42 is constructed with 316 stainless steel wetted parts and chemically resistant elastomers (e.g., Kalrez® and Viton®), ensuring compatibility with aggressive gases and high-purity environments. It meets CE marking requirements for electromagnetic compatibility (EN 61326-1) and low-voltage directive (2014/35/EU). For regulated laboratory and manufacturing settings, the controller supports audit-ready operation: all parameter changes, setpoint adjustments, and calibration selections are timestamped and logged internally (non-volatile memory, 10,000-event capacity), aligning with GLP/GMP documentation practices. While not inherently 21 CFR Part 11 compliant, its deterministic firmware behavior, write-protected calibration tables, and RS-232 log export capability facilitate validation under FDA-regulated workflows.
Software & Data Management
No proprietary software is required for basic operation—the unit is fully functional via front-panel six-button keypad navigation. However, optional terminal emulation (e.g., Tera Term, PuTTY) enables remote configuration, real-time data streaming, and batch logging of flow, temperature, and pressure values at up to 10 Hz. All communications adhere to a documented ASCII command protocol, permitting seamless integration into Python, MATLAB, or custom C# automation frameworks. Internal data storage retains last-known setpoints, gas selection, and operational mode across power cycles. Firmware updates are performed via RS-232 using signed hex files, with checksum verification prior to flash programming.
Applications
- Gas blending and ratio control in semiconductor process tools (e.g., ALD, PECVD precursors).
- Calibration transfer standards for secondary flow meters in metrology labs (per ISO/IEC 17025).
- Inert gas purging and atmosphere control in gloveboxes and anaerobic chambers.
- Exhaust stream monitoring and emission testing where bidirectional flow reversal simulates cyclic ventilation profiles.
- Research-scale electrochemical gas consumption/evolution studies (e.g., CO₂ electrolysis, PEM fuel cells).
- Pharmaceutical lyophilization cycle development requiring precise inert gas backfilling and vacuum ramping.
FAQ
Is the device certified for use with explosive atmospheres?
No—this model is not ATEX, IECEx, or UL HazLoc certified. It is intended for use in general laboratory and industrial environments with appropriate external gas handling safeguards.
Can I change the gas type remotely via RS-232?
Yes—gas selection is fully programmable via ASCII command (e.g., “GAS=O2”) and persists through power cycles.
Does it support Modbus RTU or Ethernet connectivity?
No—only 0–5 V analog and RS-232 serial interfaces are provided. Third-party protocol converters may be used for Modbus translation.
What is the maximum allowable system pressure?
The standard version is rated for 100 psia maximum inlet pressure; high-pressure variants (up to 300 psia) are available under custom order.
How often does the unit require recalibration?
Cole-Parmer recommends annual verification against a traceable reference standard; factory recalibration is available through authorized service centers.
