Dwyer AVU - Manual

The Series AVU Air Velocity Transmitters from Dwyer
Instruments are suitable for measuring air velocity within a duct
and giving 4-20 mA or 0-10 V linear outputs. A typical application
would be in a VAV air conditioning system.
The transmitters operate by measuring the heat loss from one of
two sensing elements in the airstream and hence calculating the
air velocity. The special design of these elements makes the trans-
mitter accurate over the whole air velocity range and gives excel-
lent immunity to drift.
The sensing elements are clad in metal ensuring a long service life
and enabling the sensors to be cleaned easily.
INSTALLATION
Electromagnetic Compatibility
Series AVU Air Velocity Transmitters have built in immunity to elec-
trical interference. However, to achieve full immunity meeting the
standards described below, a screened cable must be used cor-
rectly. The cable screen must be earthed at the enclosure of the
controller/power supply and connected to the screen inside the
AVU casing using the procedure described on the back page. The
inside of the transmitter and the sensing elements near the end of
the probe must be protected from electrostatic discharge at all
times.
EMC Standards:
Immunity:
BS EN 50082-1: 1992
Emissions: BS EN 50081-1: 1992
Series AVU Air Velocity Transmitter
Specifications - Installation and Operating Instructions
Bulletin H-20
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: [email protected]
SPECIFICATIONS
Service: Clean air and compatible, non-combustible gases.
Accuracy: ±5% of full scale.
Response Time (90%): 5 sec (typical).
Temperature Limits: 32 to 122°F (0 to 50°C).
Humidity Limit: 0-90% RH, non-condensing.
Power Requirements: -A models 24 VDC +10% -15%;
-V models 24 VDC or 24 VAC +10% - 15%.
Output Signal: -A models 4-20 mA current loop;
-V models 0-10 VDC.
Loop Resistance: (-A models) 700 ohms.
Current Consumption: 60 mA + output current.
Max. Start Up Current: 85 mA; 10 V.
Output Current Limit: (-V models) >10 mA.
Electrical Connections: Screw terminal. Cable gland for 4-8
mm wire (16 gauge wire).
Enclosure Rating: NEMA 6 (IP67) except sensing point.
Probe Dimensions: 9.45 x .75˝ (240 x 19 mm).
Mounting Orientation: Unit not position sensitive. Probe must
be aligned with airflow.
Weight: 8.8 oz (250 g).
Agency Approvals: CE.
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