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B DIMENSION
SERIES 641
E
AIR VELOCITY TRANSMITTERS
High Accuracy, Field Selectable Ranges
CALIBRATION SERVICES AVAILABLE
AIR QUALITY
E
O
D
I
V
O
N
L
I
N
4-29/64
13.11]
4-29/64
[113.11]
1/2 NPT
1/2 NPT
A DIMENSION
3-1/4
[82.55]
B DIMENSION
A DIMENSION
2-23/32
[29.06]
1/2-14 NPT
1/2-14 NPT
13/16
[20.64]
25/32
[19.84]
641 AVT WITH DISPLAY OPTION
A Dimension B Dimension
7-63/64 [202.80]
13-63/64 [355.20]
19-63/64 [507.60]
26-63/64 [685.40]
32-63/64 [837.80]
37-63/64 [964.80]
641 AVT WITHOUT DISPLAY OPTION
A Dimension B Dimension
7-7/16 [188.91]
13-7/16 [341.31]
19-7/16 [493.71]
26-7/16 [671.51]
29-7/16 [747.71]
37-7/16 [950.91]
9-13/16 [249.24]
15-13/16 [401.64]
21-13/16 [554.04]
28-13/16 [731.84]
34-13/16 [884.24]
39-13/16 [1011.24]
9-9/32 [235.74]
15-9/32 [388.14]
21-9/32 [540.54]
28-9/32 [718.34]
34-9/32 [870.74]
39-9/32 [997.74]
The Series 641 Air Velocity Transmitters are the ideal instrument for monitoring air
ow. This transmitter uses a heated mass ow sensor which allows for precise velocity
measurements at various ow rates and temperatures. The 641’s 16 eld-selectable
ranges provides it the versatility to be selected for several air ow applications. The
optional LED produces a complete, low-cost solution for local indication of air ow.
BENEFITS/FEATURES
• Ranges from 250 FPM (1.25 MPS) to 15,000 FPM (75 MPS)
• Optional bright LED display
• Easy push-button set-up
• Compact housing
• 4-20 mA output
• Digital lter for signal damping
APPLICATIONS
• Exhaust stack ow monitoring
• Air control in drying processes
Air Velocity Transmitters
• HVAC air velocity measurements
• Fan supply and exhaust tracking
• Clean room ventilation monitoring
MODEL CHART
Model Probe Length*
641-6
641-6-LED
641-12
641-12-LED
641-18
641-18-LED
641-24
641-24-LED
*Other probe lengths available contact factory.
6˝ (152.4 mm)
6˝ (152.4 mm)
12˝ (304.8 mm)
12˝ (304.8 mm)
18˝ (457.2 mm)
18˝ (457.2 mm)
24˝ (609.6 mm)
24˝ (609.6 mm)
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 and 122 to 212°F (-40 to 0°C and 50 to 100°C).
Response Time: Flow: 1.5 s to 95% of nal value (output lter 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. 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 (s).
Loop Resistance: 600 Ω max.
Current Consumption: 300 mA max.
Electrical Connections: Screw terminal.
Process Connections: 1/2˝ male NPT.
Enclosure Rating: Designed to meet NEMA 4X (IP66) for non LED models only.
Mounting Orientation: Unit not position sensitive. Probe must be aligned with
airow.
Weight: 12.6 oz (357.2 g).
Compliance: CE.
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: 13.3 oz (377 g).
OPTIONS
To order add sufx: Description
-NIST NIST traceable calibration certicate
Example: 641-6-NIST
ACCESSORIES
Model Description
A-156
A-158
A-159
641-LED
DWYER INSTRUMENTS, LLC | dwyer-inst.com218
Universal mounting plate, 1/2˝ female NPT
Split ange mounting kit
Duct mounting gland
Field-upgradeable LED
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