The Series 641RM is the ideal instrument for monitoring air flow. This transmitter uses a heated mass flow sensor, which allows for precise velocity measurements at various flow rates and temperatures. The 641’s 16 field selectable ranges from 0-250 to 15,000 FPM (0-1.25 to 75 MPS) provide it the versatility to be selected for a multitude of applications. The units 6' cable which connects the sensing probe with the electronic enclosure allows the enclosure to be mounted where it can be more easily accessed. Longer cable lengths are available fro ducts that are at very high elevations from the plant floor. The optional LED produces a complete, compact solution for local indication of air flow.

SPECIFICATIONS
Service: Clean air and compatible, non-combustible gases.
Accuracy:
3% FS Process gas: 32 to 122°F (0 to 50°C).
4% FS Process gas: -40 to 32°F & 122 to 212°F
(-40 to 0°C & 50 to 100°C).
Response Time: Flow: 1.5 seconds to 95% of final value (output filter set to minimum).
Temperature Limits: Process: -40 to 212°F (-40 to 100°C). Ambient: 32 to 140°F (0 to 60°C).
Pressure Limit: 100 psi (6.89 bar) maximum.
Humidity Limit: Non-Condensing.
Power Requirements: 12–35 VDC, 10–16 VAC.
Output Signal: 4-20 mA, isolated 24V source, 3 or 4-wire connection.
Output Filter: Selectable 0.5 –15 (seconds).
Loop Resistance: 600 ohms max.
Current Consumption: 300 mA max.
Electrical Connections: Screw terminal.
Mounting Orientation: Unit not position sensitive. Probe must be aligned with airflow.
Weight: 13.2 oz (374.26 g).
Cable Length: 6 ft (1.82 m).
Probe Length: 12" (30.48 cm) standard.
Probe Diameter: 5/16" (0.79 cm).

OPTIONAL DISPLAY VERSION:
Display: 4-1/2 digit 1/2" red LED.
Resolution: 1 FPM, 0.01 MPS (10 FPM @ 10,000 and 15,000 FPM ranges).
Weight: 13.9 oz (394.16 g).

ACCESSORIES -- See "Ordering" page
A-155 - Mounting Gland with 1/2" male NPT fitting
A-156 - Flange Mounting Plate with 1/2" female NPT