Cole-Parmer Model 32648-00 Digital Compact Thermal Mass Flow Meter

Overview

The Cole-Parmer Model 32648-00 is a compact, digitally displayed thermal mass flow meter engineered for high-accuracy, real-time measurement of gas mass flow rates under varying pressure and temperature conditions. Unlike volumetric flow devices, this instrument employs constant-temperature anemometry (CTA) — a well-established thermal dispersion principle — to directly quantify mass flow in standard liters per minute (SLPM) without requiring external temperature or pressure compensation. The straight-tube sensor design minimizes pressure drop and eliminates moving parts, ensuring long-term stability and resistance to clogging from particulates up to 5 µm. Its immunity to inlet pressure and ambient temperature fluctuations (±0.15%/°C and ±0.01%/psi full-scale drift coefficients) makes it suitable for integration into gas delivery systems, laboratory reactors, environmental test chambers, and semiconductor process lines where consistent stoichiometric control is critical.

Key Features

• True thermal mass flow sensing with no moving components — delivers high reproducibility (±0.5% FS) and minimal maintenance requirements
• Factory-calibrated for air and nitrogen; NIST-traceable calibration certificate supplied with each unit
• Dual analog output options: isolated 0–5 VDC and/or 4–20 mA signals, both linear across full scale
• Rotatable 3.5-digit LCD display (removable for panel mounting or remote viewing)
• Integrated polarity-protected 12 VDC power input (max 200 mA) with resettable fuse for reverse polarity and short-circuit protection
• Configurable housing material: anodized aluminum (wetted parts: anodized Al, brass, Viton®) or 316 stainless steel (wetted parts: 316 SS, Viton®)
• Optional add-on cumulative flow display module (Model 32650-70) for totalized gas consumption tracking
• Optional analog-to-serial interface module available for RS-232/RS-485 data acquisition and PC-based logging

Sample Compatibility & Compliance

The Model 32648-00 is validated for use with clean, dry, non-corrosive gases including air, nitrogen, argon, helium, carbon dioxide, and oxygen. It is not rated for use with condensing vapors, aggressive chemicals (e.g., Cl₂, NH₃, H₂S), or high-viscosity gases. All wetted materials comply with USP Class VI biocompatibility standards for inert gas handling in pharmaceutical and life science applications. The device meets CE marking requirements for electromagnetic compatibility (EMC Directive 2014/30/EU) and low-voltage safety (LVD Directive 2014/35/EU). While not intrinsically safe, its low-power design (12 VDC) supports use in non-hazardous locations per NEC Class I, Division 2 guidelines. Units are supplied with documentation supporting GLP-compliant installation qualification (IQ) and operational qualification (OQ) protocols.

Software & Data Management

Although the base unit operates autonomously without software, optional serial interface modules enable seamless integration with LabVIEW™, MATLAB®, or custom SCADA platforms via Modbus RTU or ASCII protocol. Data streams support timestamped acquisition at up to 10 Hz sampling rate. When deployed in regulated environments (e.g., FDA 21 CFR Part 11-compliant labs), the analog outputs can be connected to validated PLC-based data loggers with audit trail functionality. The 4–20 mA output is compatible with most industrial DCS systems and provides inherent noise immunity over extended cable runs. No firmware updates or driver installations are required for basic analog operation — ensuring deterministic behavior in mission-critical gas control loops.

Applications

• Precise gas dosing in chemical vapor deposition (CVD) and atomic layer deposition (ALD) tools
• Leak testing and purge verification in vacuum systems and gloveboxes
• Calibration reference for secondary flow sensors in HVAC and cleanroom monitoring
• Mass flow monitoring in fuel cell test benches and hydrogen safety systems
• Gas blending and ratio control in analytical instrumentation (e.g., GC carrier gas, ICP-MS nebulizer gas)
• Environmental chamber inflow/outflow quantification for ISO 14644-3 particle containment validation

FAQ

Is the Model 32648-00 suitable for measuring humidified gases?
No — moisture condensation may impair sensor accuracy and longevity. For humid gas applications, upstream drying or use of a corrosion-resistant variant with heated sensor elements is recommended.

Can this flow meter be used with corrosive gases such as chlorine or ammonia?
No — wetted materials are incompatible with oxidizing or highly reactive gases. Consult Cole-Parmer’s GFMS series with Hastelloy® or PFA-lined variants for such media.

Does the unit require periodic recalibration?
Annual recalibration is recommended for GLP/GMP compliance. NIST-traceable recalibration services are available through Cole-Parmer’s certified metrology lab.

What is the maximum allowable differential pressure across the sensor?
The device is rated for system pressures up to 500 psi; however, differential pressure should remain below 5 psi to maintain specified accuracy and avoid mechanical stress on the thermal sensor element.

Is the 4–20 mA output active or passive?
It is a 2-wire active loop-powered output, compatible with standard current-input PLC modules and data loggers.