Cole-Parmer 32700-18 Gas Flow Sensor and Totalizer

Overview

The Cole-Parmer 32700-18 Gas Flow Sensor and Totalizer is a precision-engineered inline device designed for real-time measurement and cumulative recording of gas flow rates in low-pressure, clean, non-corrosive gaseous environments. Built upon thermal mass flow sensing technology, it operates on the principle of heat transfer differential across a micro-machined sensor element—providing direct mass flow measurement independent of gas temperature and pressure fluctuations within specified operating ranges. This eliminates the need for external compensation algorithms or secondary transducers, ensuring high reproducibility and long-term stability in laboratory, pilot-scale process control, and analytical gas delivery applications. The unit is calibrated for air at standard conditions (25 °C, 101.325 kPa), with optional factory calibration available for nitrogen, argon, oxygen, CO₂, and other common industrial gases per ISO 6145-7 traceable protocols.

Key Features

• Thermal mass flow sensing architecture with no moving parts—ensuring maintenance-free operation and immunity to particulate fouling in filtered gas streams
• Integrated digital totalizer with non-volatile memory retention—preserving accumulated flow data during power interruption
• 0–10 VDC analog output and RS-232 serial interface for seamless integration into SCADA systems, PLCs, or custom LabVIEW-based acquisition platforms
• Front-panel LCD display with dual-line readout: instantaneous flow rate (SLPM) and totalized volume (SL)
• Compact NPT 1/4″ male inlet/outlet configuration compatible with standard Swagelok® and Parker A-LOK® tubing fittings
• Operating range: 0–10 SLPM full scale (custom ranges 0–1 to 0–50 SLPM available upon request); accuracy ±1.5% of reading ±0.2% of full scale; repeatability ±0.5% of reading
• Power supply: 12–24 VDC, reverse-polarity protected; consumption <1.2 W

Sample Compatibility & Compliance

The 32700-18 is validated for use with dry, particle-free gases including air, nitrogen, oxygen, helium, argon, carbon dioxide, and synthetic natural gas blends. It is not suitable for corrosive, condensing, or high-humidity gas streams without upstream conditioning (e.g., desiccant drying or coalescing filtration). All wetted materials—stainless steel 316L sensor body, glass-reinforced polyphenylene sulfide (PPS) housing, and platinum RTD elements—comply with USP Class VI biocompatibility requirements and meet ASTM F828-22 standards for polymer components in gas handling systems. Device firmware supports audit-trail logging for GLP/GMP-aligned workflows, and its analog output conforms to NIST-traceable calibration documentation per ISO/IEC 17025:2017 accredited procedures.

Software & Data Management

While the 32700-18 operates autonomously as a stand-alone instrument, its RS-232 interface enables bidirectional communication using ASCII command protocol (Cole-Parmer proprietary syntax, documented in User Manual Rev. D). Third-party software integration—including MATLAB, Python (pySerial), and National Instruments DAQmx—is supported via standard serial drivers. Data export formats include CSV and tab-delimited text files, timestamped with internal real-time clock (RTC) synchronized to host system time. For regulated environments, optional firmware upgrade (v3.2+) adds 21 CFR Part 11-compliant electronic signature capability, user access levels (Admin/Operator/Viewer), and immutable event logs covering calibration history, parameter changes, and totalizer resets.

Applications

• Gas flow verification in environmental chamber purge cycles and controlled-atmosphere gloveboxes
• Cumulative dosing control in catalytic reactor feed systems and semiconductor process gas delivery
• Leak testing validation where precise volumetric displacement over time must be quantified
• Calibration reference for rotameters, vortex meters, and ultrasonic flow sensors in metrology labs
• Research-grade gas blending systems requiring stoichiometric ratio monitoring (e.g., O₂/N₂ mixtures for combustion studies)
• Regulatory submissions requiring documented gas consumption records—such as EPA Method 25A compliance verification or ISO 14644-3 cleanroom certification

FAQ

Is the 32700-18 suitable for measuring humidified or compressed natural gas?
No. The sensor requires dry, non-condensing gas streams. Humidity above 60% RH or hydrocarbon-laden gases may cause drift or sensor degradation. Use with inline desiccant dryers and particulate filters is mandatory.
Can I re-range the device in the field?
No. Full-scale range is fixed at time of manufacture. Custom range configurations must be specified prior to order fulfillment.
Does it support Modbus RTU or Ethernet connectivity?
Not natively. Only RS-232 and 0–10 VDC analog outputs are provided. Modbus conversion requires an external protocol gateway; Ethernet integration necessitates a serial-to-Ethernet server.
What is the recommended recalibration interval?
Cole-Parmer recommends annual recalibration against a NIST-traceable master flow standard under actual operating conditions, especially when used in GxP-regulated settings.
Is explosion-proof certification available?
The standard 32700-18 is not rated for hazardous locations. For Class I, Div 1 environments, consult Cole-Parmer’s certified partner program for intrinsically safe variants (e.g., model 32700-18-EX with FM/ATEX approval).