Dwyer Instruments 641 series User Manual

Series 641 Air Velocity Transmitter
Specifications - Installation and Operating Instructions
Bulletin E-66CE
DWYER INSTRUMENTS, INC. Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: info@dwyer-inst.com
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.
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).
DWYER INSTRUMENTS, INC. 102 INDIANA HWY 212 MICHIGAN CITY, IN 46360
DWYER INSTRUMENTS, INC. 102 INDIANA HWY 212 MICHIGAN CITY, IN 46360
PHONE: 219-879-8000
e-mail: info@dwyer-inst.com
http://www.dwyer-inst.com
PHONE: 219-879-8000
e-mail: info@dwyer-inst.com
http://www.dwyer-inst.com
4-29/64
[113.11]
1/2 NPT
1/2-14 NPT
13/16
[20.64]
B DIMENSION
A DIMENSION
3-1/4
[82.55]
B DIMENSION
A DIMENSION
2-23/32
[29.06]
4-29/64
[113.11]
1/2 NPT
1/2-14 NPT
25/32
[19.84]
A 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]
B DIMENSION
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]
641 AVT WITH DISPLAY OPTION
641 AVT WITHOUT
DISPLAY OPTION
A 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]
B DIMENSION
9-9/32
[235.74]
15-9/32
[388.14]
21-9/32
[540.54]
26-9/32
[718.34]
34-9/32
[870.74]
39-9/32
[997.74]
641-CE bulletin 11/9/04 3:49 PM Page 1
1.800.868.7495
QualityInstruments-Direct.ca

Dwyer Instruments 641 series Specifications

General

Model	641 Series
Category	Transmitter
Manufacturer	Dwyer Instruments
Output Signal	4-20 mA
Agency Approvals	CE
Relative Humidity	0-95% non-condensing

Summary

Specifications

Service

Defines the type of air and compatible gases the transmitter can be used with.

Accuracy

Specifies the accuracy of the process gas measurement at different temperature ranges.

Response Time

Indicates the time it takes for the output to reach 95% of the final value.

Temperature Limits

Defines the operating temperature ranges for both process and ambient conditions.

Pressure Limit

Specifies the maximum allowable pressure for the transmitter.

Humidity Limit

Defines the acceptable humidity conditions for operation (non-condensing).

Power Requirements

Details the voltage and current requirements for powering the transmitter.

Output Signal

Describes the isolated 4-20 mA output signal and connection types.

Output Filter

Specifies the selectable output filter for smoothing readings in turbulent flow.

Loop Resistance

Indicates the maximum allowable loop resistance for proper operation.

Current Consumption

States the maximum current the transmitter will draw.

Electrical Connections

Details the type of screw terminals used for electrical connections.

Process Connections

Specifies the 1/2" male NPT for process connections.

Mounting Orientation

States that the unit is not position sensitive but the probe must align with airflow.

Weight

Provides the weight of the transmitter.

Agency Approvals

Lists CE approval standards used for the product.

Optional Display Version

Details the specifications for the optional 4-1/2 digit LED display.

Installation

Location

Guidance on selecting a suitable location for mounting the enclosure based on temperature.

Position

Notes that the transmitter is not position sensitive but the probe must align with airflow.

Mounting

Instructions for mounting the transmitter using integral 1/2" NPT or compression fittings.

Airflow

Recommendations for using the transmitter with clean, dry air and avoiding dust accumulation.

Electrical Connection

3 or 4-Wire Connection

Explains the flexible connection options for power and loop receivers.

Receiver-Transmitter Connection

Describes the isolated current loop output and cautions against external supplies.

Power Supply Connection

Details power supply options (AC or DC) and recommended voltages.

Wire Type and Length

Provides guidelines for wire selection and length to ensure satisfactory operation.

Transmitter Setup

Range Selection

Instructions for selecting one of eight ranges in FPM or MPS.

Adjusting the Output Filter

Guidance on adjusting the output filter time constant for damping.

Span Setting

Process for adjusting the span to correct for altitude or static pressure changes.

4 mA Setting

Procedure for calibrating the 4 mA set-point using a milliammeter.

20 mA Setting

Procedure for calibrating the 20 mA set-point using a milliammeter.

Restoring Factory Default Settings

Steps to restore factory default settings for range, 4 mA, and 20 mA.

Maintenance

Cleaning the Sensor

Instructions for cleaning the sensor to remove dust accumulation.

Factory Calibration

Information on returning the unit to Dwyer Instruments for factory calibration.

CE Approvals