Dwyer Instruments 641 series Installation And Operating Instructions

The Series 641 Air Velocity Transmitter (AVT) uses a
heated mass flow sensor technology. It has 8 user selec-
table ranges from 250 FPM to 15000 FPM with corre-
sponding metric ranges of 1.25 MPS to 75 MPS. The
Series 641 AVT provides an isolated 4-20 mA output pro-
portional to the velocity. With the optional 1/2˝ 4-1/2 digit
LED display, the Series 641 AVT will provide a highly visible
local readout of the velocity.
INSTALLATION
Location: Select a location where the temperature will be
within 32 to 140°F (0 to 60°C) to mount the enclosure. The
transmitter may be located any distance from the receiver
provided that the total loop resistance does not exceed 600
ohms. The probe should be located where conditions are
representative of the overall environment being monitored.
Avoid locations where turbulence, stagnation, or rapidly
fluctuating velocities or temperatures are present as these
conditions may affect the readings. The filter setting may be
used to average velocity readings in turbulent conditions.
Position: The transmitter is not position sensitive and may
be mounted in any orientation.
Mounting: An integral 1/2˝ NPT allows direct mounting to
pipe fittings or a pipe flange. The Series 641 AVT may also
be mounted using a 5/16˝ compression fitting. Arrows on
the hex flats at the base of the probe indicate the direction
of the calibrated airflow. Align these arrows in the direction
of the process air. The case may be rotated independently
of the probe for ease of connection.
Airflow: The Series 641 AVT is intended for use with clean
dry air. Particulates in the air may cause sensor damage.
Dust accumulation may impair the velocity measurement
and will require probe cleaning.
DWYER INSTRUMENTS, INC.
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A.
Series 641 Air Velocity Transmitter
Specifications - Installation and Operating Instructions
QualityInstruments-Direct
B DIMENSION
A DIMENSION
3-1/4
[82.55]
1/2-14 NPT
4-29/64
[113.11]
1/2 NPT
B DIMENSION
A DIMENSION
2-23/32
[29.06]
1/2-14 NPT
4-29/64
[113.11]
1/2 NPT
SPECIFICATIONS
Service: 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: 4-20mA, 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.
Process Connections: 1/2˝ male NPT.
Mounting Orientation: Unit not position sensitive.
Probe must be aligned with airflow.
Weight: 12.6 oz. (357.2 g).
Agency Approvals: CE (See text for test standards).
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).
Phone: 219/879-8000
.ca
Fax: 219/872-9057
Bulletin E-66CE
641 AVT WITH DISPLAY OPTION
A DIMENSION
B DIMENSION
7-63/64 9-13/16
[202.80]
[249.24]
13/16
13-63/64 15-13/16
[20.64]
[355.20]
[401.64]
19-63/64
21-13/16
[507.60] [554.04]
26-63/64
28-13/16
[685.40] [731.84]
32-63/64 34-13/16
[837.80]
[884.24]
37-63/64 39-13/16
[964.80]
[1011.24]
641 AVT WITHOUT
DISPLAY OPTION
A DIMENSION B DIMENSION
7-7/16 9-9/32
25/32
[188.91] [235.74]
[19.84]
13-7/16 15-9/32
[341.31] [388.14]
19-7/16 21-9/32
[493.71] [540.54]
26-7/16 26-9/32
[671.51] [718.34]
29-7/16 34-9/32
[747.71] [870.74]
37-7/16 39-9/32
[950.91] [997.74]
www.dwyer-inst.com
1.800.868.7495
e-mail: info@dwyer-inst.com