RAQ
The RAQ air volume VAV units can be
used for the accurate regulation of air-
flow in square shaped air ductwork and
for keeping it constant.
The RAQ air volume controller unit can
invariably be used for supply and extrac-
tion of air.
Operating temperature: -20 to +60°C
Ambient temperature: 0 to +50°C.

Operation
The device consists of one air velocity sensor. The signal gene-
rated by the measurement regulates the actuator and then the
opening of the regulating damper.
The pressure difference between the measuring components
positioned on both sides of the air velocity sensing measuring
bridge is, at high accuracy, proportionate to the air velocity, and
thus, to the air volume flowing through the device.

Execution
The RAQ air volume controllers are available in 14 standard si-zes.
Materials used in manufacturing: galvanized steel sheet, alumi-
nium section-pieces and plastic components.
If requested, the RAQ unit is also available in sound-attenuated
version RAR (50 mm thickness).

Selection
The RAQ air volume controller units can be selected subject to
the data indicated in the tables and diagrams. Diagram 1 shows
the pressure drops appearing in open position, in the range
between noise outputs 45 and 70 [dBA]. It is to be noted that
this noise output is not identical with the sound pressure level
noticeable outside the duct. Namely, the establishing of this
requires detailed calculations, where, in addition to the sound-
attenuation of approx. 8 [dB] provided by the duct’s sheet wall,
the sound attenuation rendered by the other encircling surfaces
and by the room itself have to be considered. And, in calculating
the noises spreading into the interior of the air duct system, in
addition to the length of the ductwork, the geometry and the
sound-attenuation by other installed components have a signi-
ficant role.

Installation
The RAQ air volume controller can be installed in any position.
The condition required for correct operation is that the airflow
should always proceed from the measuring bridge toward the re-
gulating blades. With a view to providing precise operation, it is
necessary to extabilish an approx. 500 mm long straight-line air
duct section on the inlet side of the RAQ air volume controller.

Sound level data
The next tables contain the per-octave band sound output data
of the RAQ air volume controller units, in the case of average
velocity values calculated for different pressure drops and con-
necting cross-sections. Intermediate values can be calculated at
satisfactory accuracy, by the way of interpolation.