The Dwyer 641RM air velocity transmitter combines the proven heated mass flow sensor technology of the Series 641 with a convenient remote probe design. The 6-foot cable connecting the sensing probe to the electronics enclosure allows the transmitter to be mounted in an accessible location while the probe remains in the duct or stack—ideal for tight spaces or high-temperature environments.

Field-selectable ranges cover from 250 FPM (1.25 MPS) to 15,000 FPM (75 MPS), accommodating a wide variety of airflow applications. The 4-20 mA output provides seamless integration with building management systems, PLCs, and data loggers. An optional LED display offers local readout, while push-button setup and a digital filter for signal damping simplify configuration and improve stability in turbulent flows.

Typical applications include:

• Exhaust stack flow monitoring
• Air control in drying processes
• HVAC air velocity measurements
• Fan supply and exhaust tracking
• Clean room ventilation monitoring

Features

• Remote probe with 6 ft cable for flexible installation
• Heated mass flow sensor technology
• Velocity ranges: 250 to 15,000 FPM (1.25 to 75 MPS)
• 4-20 mA output
• Optional LED display
• Push-button setup
• Digital filter for signal damping
• Compact housing