Dwyer Instruments 641-12-LED
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$722
High-precision air velocity transmitter with a 12-inch probe, LED display, and selectable ranges. Designed for clean air applications in HVAC, lab environments, and industrial flow monitoring.
Dwyer 641 [641-12-LED] Air Velocity Transmitter 12 Inch Probe Length with LED Display.
The Dwyer 641-12-LED Air Velocity Transmitter is a rugged and reliable solution for air flow measurement in a wide range of environmental and industrial applications. Equipped with a 12-inch probe and a bright LED display, this unit provides real-time, accurate air velocity readings using a heated mass flow sensor. Its field-selectable ranges and 4-20 mA output make it ideal for integration into various control systems.
With an impressive ±3% accuracy, a 1.5-second response time, and robust build quality, the 641-12-LED supports monitoring for cleanrooms, HVAC systems, lab hoods, and process exhaust systems—making it a valuable tool in any environmental testing workflow.
Key Features
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12″ stainless steel probe for deeper air duct or stack penetration
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LED display provides local, real-time indication
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16 field-selectable flow ranges, up to 15,000 FPM (75 MPS)
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Heated mass flow sensor for precise and repeatable velocity measurements
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±3% full-scale accuracy at standard temperature ranges
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Fast 1.5 second response time to 95% of final value
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4-20 mA isolated output with 3 or 4-wire connection
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Selectable digital filter for signal damping
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Push-button setup for easy configuration
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NEMA 4X/IP66 design (non-LED models) for industrial-grade durability
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CE certified
Why Choose the Dwyer 641-12-LED?
This air velocity transmitter delivers professional-grade accuracy and flexibility for engineers and facility managers who need trustworthy airflow data. The LED version adds a cost-effective local display, improving diagnostics and maintenance efficiency. Whether you’re managing HVAC air balance, cleanroom pressurization, or process ventilation, this transmitter is built to perform in demanding environments.
Explore more instruments in our Air Flow Measurement category or read our full guide: Environmental Test Equipment — Tools for Climate, Humidity, and Vibration Analysis.
What’s Included
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(1) Dwyer 641-12-LED Air Velocity Transmitter
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(1) Instruction Manual
Technical Specifications
| Specification | Details |
|---|---|
| Service | Clean air, compatible non-combustible gases |
| Accuracy | ±3% FS (32 to 122°F), ±4% FS (-40 to 0°C / 50 to 100°C) |
| Response Time | 1.5 seconds to 95% of final value |
| Temperature Limits | Process: -40 to 212°F; Ambient: 32 to 140°F |
| Pressure Limit | 100 psi (6.89 bar) |
| Humidity Limit | Non-condensing |
| Power Requirements | 12–35 VDC or 10–16 VAC, 1.5A surge rating |
| Output Signal | 4–20 mA, isolated 24V source |
| Output Filter | Selectable: 0.5 to 15 seconds |
| Loop Resistance | 600 Ω max |
| Current Consumption | 300 mA max |
| Electrical Connection | Screw terminal |
| Process Connection | 1/2″ male NPT |
| Enclosure Rating | NEMA 4X (IP66) for non-LED models |
| Mounting Orientation | Probe aligned with airflow (unit position insensitive) |
| Weight | 13.3 oz (377 g) with LED display |
| Display (Optional) | 4½ digit, ½” red LED, 1 FPM resolution |
| Agency Approval | CE |
Applications
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Exhaust stack airflow monitoring
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HVAC system diagnostics and optimization
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Cleanroom air supply and return verification
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Lab hood exhaust compliance
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Air control in drying or curing processes
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Fan performance tracking in industrial facilities
