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1

1.0 Introduction

This constant volume damper is designed for installation with

Nuaire’s range of fans. 

Units are rectangular in section, manufactured from galvanised

steel.

The CVD damper will control the flowrate passing through it when

the pressure drop across the damper is within the range stated in

the performance envelope. 

Two flow settings are available; trickle and boost. The damper will

operate in the trickle setting when it is powered up and will go into

the boost setting when a mains signal is received at the SL terminal

or when the CVD-PIR (optional ancillary) is activated. A run-on timer

(adjustable between 1 to 60 minutes) will hold the damper in the

boost setting for the preset time period.

2.0 Dimensions

Figure 1.

Dimensions in mm.
Code 

F

kg

CVD125 

300

180

195

125

75

400

3.5

CVD150

300

200

220

150

90

400

3.7

CVD200

300

230

275

200

115

400

4

3.0 Handling

Handle the units carefully to avoid damage and distortion to 

moving parts.

4.0 System Design

A nominal pressure drop must be allowed in order to ensure 

adequate airflow through the damper. To ensure the airflow

pattern through the damper produces consistent readings; the

pressure drop across the damper should not exceed the 

recommended value. Recommended values are listed in the table

following and show the performance envelope of each damper.

Nominal design pressure is the value needed to produce the 

maximum rated airflow for the damper. If the desired flowrate 

is less than the maximum, a lower design value may be used 

by reading off the lower curve of the appropriate chart. Please

allow 40Pa (min).

Model code

Nominal design

Maximum pressure

pressure drop

across damper*

CVD125 

70Pa 

140Pa

CVD150 

80Pa 

160Pa

CVD200 

90Pa**

200Pa

*recommended maximum operating pressure to ensure the damper

would work within calibration limits.

Keep the duct velocity as low as possible to ensure the system 

produces the lowest energy usage, preferably below 5m/s.

**Allow 90Pa for duties below 100l/s and 150Pa for duties between

100l/s and 125l/s.

CVD125/150/200

Constant Volume Dampers

Installation and Maintenance

10. 05. 17. Leaflet Number 671638

D

B

C

A

F

E

Trickle

Boost 

Run-on

10

15

20

5

25

10

15

20

5

25

15

30

45

1

60

Airflow

0

20

40

60

80

100

120

0

10

20

30

40

50

60

Pr

essur

e dr

op P

a

design pressure

140

160

180

Volume flowrate l/s

Figure 2. Performance envelope for CVD125.

Plan view

Side view

0

50

100

150

0

20

40

60

80

100

Pr

essur

e dr

op P

a

design pressure

200

250

Volume flowrate l/s

Figure 3. Performance envelope for CVD150.

0

50

100

150

0

20

40

60

80

160

Pr

essur

e dr

op P

a

Nominal design pressure

200

250

Volume flowrate l/s

300

*

100

120

140

Figure 4. Performance envelope for CVD200.

*Allow 90Pa for duties below 100l/s and 150Pa for duties between

100l/s and 125l/s.

The EMC Directive 

2014/30/EU  

The Low Voltage 

Directive 

2014/35/EU

Nuaire: A Trading Division of Polypipe Limited  

Western Industrial Estate

 

Caerphilly  United Kingdom  CF83 1NA  

T: 029 2088 5911  F: 029 2088 7033  E: [email protected]  W: www.nuaire.co.uk

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