Dwyer AVUB User Manual

Bulletin AQ-AVUB

Series AVUB Air Velocity Transmitter

Specifications - Installation and Operating Instructions

The Series AVUB Air Velocity Transmitters from Dwyer Instruments are suitable for measuring air velocity within a duct and giving a 0 to 10 V linear output. 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 transmitter accurate over the whole air velocity range and gives excellent 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 Capability

Series AVUB Air Velocity Transmitters have built in immunity to electrical interference. However, to achieve full immunity meeting the standards described below, a screened cable must be used correctly. 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.

Attaching the Cable and Cable Screen

The cable gland contains a rubber insert and a plastic insert. Remove these inserts. Strip back the cable as shown below. Pass the cable through the gland outer and rubber and plastic inserts. Fold the screen back over the plastic insert evenly taking care to remove any pieces of the screen that detach. Feed the cores through into the AVUB and push the inserts back into the gland noting the orientation of the 3 pipes. Tighten the gland outer in place. Finally, connect the cores to the removable 3-way connector.

3/4			3-11/32
[19.0]			[85.0]
51/64		8-55/64
[2.0]
		[225.0]	2-1/4
	9-29/64
			[57.0]
	[240.0]

SPECIFICATIONS

Service: Clean air and compatible, non-combustible gases. Accuracy: ±8% of full scale.

Response Time (90%): 10 sec (typical).

Temperature Limits: 32 to 104°F (0 to 40°C). Humidity Limit: 0 to 90% RH, non-condensing.

Power Requirements: 24 VDC or 24 VAC +10% to 15%.

Output Signal: 0 to 10 VDC.

Max. Start Up Current: 60 mA + output current.

Electrical Connections: Screw terminal. Cable gland for 4 to 8 mm wire (16 gauge wire).

Enclosure Rating: 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).

DWYER INSTRUMENTS, INC.		Phone: [phone]	www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.		Fax: [phone]	e-mail: [e-mail]