Dwyer Instruments SERIES 641B Catalog Page
1/2 NPT
1-25/32 [45.24]
9-1/4 [235.0]
1/2 NPT
SERIES 641B
E
E
AIR VELOCITY TRANSMITTER
Dirty Air Flow Applications
E
O
D
I
V
O
N
L
I
N
1-23/32
[43.66]
4-31/32 [126.21]
The Series 641B Air Velocity Transmitter uses a heated mass ow sensor suitable
for dirty air ow applications. It has user-selectable ranges from 250 FPM (1.25 MPS)
to 2000 FPM (10 MPS).
FEATURES/BENEFITS
• SS sensor suitable for dirty air ow measurement
• Ranges from 250 FPM (1.25 MPS) to 2000 FPM (10 MPS)
• 4-20 mA output
• Digital lter for signal damping
APPLICATIONS
• Exhaust stack ow monitoring
• Air control in drying processes
• HVAC air velocity measurements
• Fan supply and exhaust tracking
• Clean room ventilation monitoring
MODEL CHART
Model Description
641B-4
641B-4-LED
Air velocity transmitter
Air velocity transmitter with LED display
SPECIFICATIONS
Service: Air and compatible, non-
combustible gases.
Accuracy: 5% FS process gas: 32 to
122°F (0 to 50°C). 6% FS process gas:
-40 to 32°F & 122 to 176°F (-40 to 0°C
and 50 to 80°C).
Response Time: Flow: 1.5 s to 95% of
nal value (output lter set to minimum).
Temperature Limits: Process: -40 to
176°F (-40 to 80°C). Ambient: 32 to
140°F (0 to 60°C).
Humidity Limit: Non-condensing.
Power Requirements: 12-35 VDC,
10-16 VAC. 1.5 A rating required on
supply due to initial power surge drawn
by transmitter.
Output Signal: 4-20 mA, isolated 24 V
source, 3- or 4-wire connection.
Output Filter: Selectable 0.5 -15
(seconds).
Loop Resistance: 600 Ω max.
Current Consumption: 300 mA max*.
Electrical Connections: Screw terminal.
Enclosure Rating: Designed to meet
NEMA 4X (IP66) for non LED models
only.
Mounting Orientation: Unit not position
sensitive.
Weight: 12.6 oz (357.2 g).
*A brief current transient exceeding 300 mA may be seen on startup
ACCESSORIES
Model Description
A-155
A-156
Mounting gland with 1/2˝ male NPT tting
Flange mounting plate with 1/2˝ female NPT
DWYER INSTRUMENTS, INC.
219
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