IRIS Damper Application Guide

INTRODUCTIONThe IRIS damper is a brilliantly simple solution for fast and exact measurement, balance and control of airflow. It is ideal for supplyand exhaust tracking control, individual comfort control, and any space requiring accurate airflow regulation. Applications for theIRIS damper include office buildings, pharmaceuticals, clean room environments and laboratories. Its unique design allows for airflowto be measured and controlled at a single station, thus saving time and money in initial installation and commissioning, and thoseapplications requiring air balance on a regular basis.

CONSTRUCTIONThe IRIS damper is comprised of a casing, damper blades, an adjustment or regulating nut, an airflow adjustment chart, and airflowtaps. Blades and casing are manufactured from either galvanized (IRIS) or 316 stainless steel (IRIS-S). The remaining componentsare made from high strength plastics and rubber.

IRIS DAMPER FEATURES & BENEFITS• Precise airflow measurement

• Accurate air balancing to +/- 5% in a straight duct

• Single station measurement and control

• Reduced field labor time

• Ideal for office buildings, pharmaceuticals, clean roomenvironments and laboratories

• Compact design, superior performance

• Fully retractable blades for duct cleaning

• Available in an assortment of sizes for a broad range ofairflow measurement requirements

POSITIVE SEAL CONSTRUCTION (OPTIONAL)Some applications may require a fully closed damper. For those requiringa 100% shutoff, a positive seal option is available on sizes 4” through 12”,in both galvanized and stainless steel IRIS dampers.

RECOMMENDED INSTALLATIONSThe calibration accuracy of an IRIS damper during disturbance free airflowis 5%. However, when an IRIS damper is installed near duct fittings,measurement accuracy may be affected. For optimum operation andairflow control, the chart (Fig. 1) indicates the recommended distancesbetween an IRIS damper and duct elbows, tees and transitions. From thechart, to achieve the airflow accuracy, m2, distance Lmin defines theminimum distance separating an IRIS damper from the fitting.

IRIS & IRIS-S DAMPERS

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IRIS DAMPER• Single station measurement and control

• Hot dipped galvanized steel construction

• Fitted EPDM gasket for airtight mounting

• Capacities: 15 cfm to 20,000 cfm

• Max operating temperature:

- 180 F continuous

- 250 F intermittent

IRIS-S STAINLESS STEEL DAMPER• AISI 316 stainless steel construction

• Prolonged excellence in extreme conditions

• Ideal for corrosive environments

• Capacities: 15 cfm to 20,000 cfm

• Max operating temperature:

- 180 F continuous

- 250 F intermittent

Lmin

m2 = +7% m2 = +10%- -

1d 1d

4d 2d

2d 2d

2d 2d

L

d

d

L L

L

d

Fig. 1

IRIS & IRIS-S DAMPERS

3

MODEL A C D L OD WT(lbs)IRIS-04, IRIS-S-04 1.2 0.6 3.9 4.6 6.5 1.1IRIS-05, IRIS-S-05 1.2 0.6 4.9 4.6 7.4 1.5IRIS-06, IRIS-S-06 1.2 0.6 5.9 4.6 9.1 2.0IRIS-08, IRIS-S-08 1.2 0.6 7.8 4.6 11.2 3.1IRIS-10, IRIS-S-10 1.6 0.7 9.8 5.3 13.2 4.6IRIS-12, IRIS-S-12 1.6 0.7 11.8 6.1 16.1 7.7IRIS-16, IRIS-S-16 2.4 0.8 15.7 7.5 20.7 14.1IRIS-20, IRIS-S-20 2.0 0.8 19.6 6.7 25.8 21.2IRIS-25, IRIS-S-25 2.0 0.9 24.7 6.7 32.1 34.4IRIS-32, IRIS-S-32 3.9 0.9 31.4 10.6 40.0 55.1

DIMENSIONS IN INCHES

IRIS DAMPER SPECIFICATION GUIDE1.0 GENERAL A. Iris dampers shall be model IRIS, as manufactured by Continental Fan Manufacturing Inc. and of the size and capacity as

indicated on the drawings and damper schedule.

2.0 DAMPER CONSTRUCTION A. Iris dampers shall be manufactured of hot dipped galvanized 22 gage steel. B. Duct connections shall be gasketed and beaded to provide for a sealed duct connection. C. Airflow measurement taps shall be provided with airflow adjustment charts located on the damper for convenient airflow

measurement and control. Damper shall be capable of controlling airflow to +/- 5% of design flow in a straight duct. D. Damper position shall be set with the factory supplied spanner wrench, with no zero calibration required. Dampers requiring

zero calibration are not acceptable. E. Casing leakage to the environment shall not exceed 6 cfm. IRIS-S STAINLESS STEEL DAMPER SPECIFICATION GUIDE1.0 GENERAL A. Iris dampers shall be model IRIS-S, as manufactured by Continental Fan Manufacturing Inc. and of the size and capacity as

indicated on the drawings and damper schedule.

2.0 DAMPER CONSTRUCTION A. Iris dampers shall be manufactured of 316 acid proof stainless steel. B. Duct connections shall be gasketed and beaded to provide for a sealed duct connection. C. Airflow measurement taps shall be provided with airflow adjustment charts located on the damper for convenient airflow

measurement and control. Damper shall be capable of controlling airflow to +/- 5% of design flow in a straight duct. D. Damper position shall be set with the factory supplied spanner wrench, with no zero calibration required. Dampers requiring

zero calibration are not acceptable. E. Casing leakage to the environment shall not exceed 6 cfm.

Product Components Material

Casing, blades Galvanized steel or acid-proofsteel (AISI 316)

Regulation mechanism Polyacetal

Stickers, window cover PVC plastic

Veloduct-sealing EPDM rubber

Measuring tap TPE rubber

MATERIAL SPECIFICATIONS ORDERING SPECIFICATIONS

IRIS-04

Product

IRIS Damper

IRIS-S Stainless Steel Damper

IRIS-PS Positive Seal Damper

Size (in.)

D

A

ODL

A C

IRIS & IRIS-S DIMENSIONS

IRIS DAMPER SELECTION CURVES

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SELECTION The criteria to be considered when applying an IRIS damper are airflow, pressure drop and sound requirements. The IRIS damperrepresents a resistance to airflow in a duct, as do the duct and fittings.

Selecting an IRIS damper is simple. In the case of an existing duct, choose an IRIS damper to match duct size.

Alternatively, use the IRIS Damper Selection Curves on pages 4 and 5. Select an IRIS damper at a mid-range setting to match desiredairflow and pressure drop. This establishes the required duct size. Additionally, this provides the end user with balancing flexibility inthe event that airflow requirements should change.

Consideration of the total pressure drop and sound requirements at design airflow is important. The Selection Curves indicate thetotal pressure drop of an IRIS damper at a given airflow and damper position.

Additionally, sound pressure curves across various damper settings are provided. LA is the sound pressure level with 4 dB roomattenuation.

2.00

1.00

0.50

0.20

0.10

0.05

0.02100070 2000100 200 500

8” Damper

45

40

50

6 5 4

3

2

1

78

dB (A)

L A.

q, cfm

Pt.

in W

G

q, cfm

Pt.

in W

G

2.00

1.00

0.50

0.20

0.10

0.05

0.0250050 100 200 700

6” Damper

45

40

50

6 5

4

3

2

1

78

dB (A)

L A.

q, cfm

Pt.

in W

G2.00

1.00

0.50

0.20

0.10

0.05

0.0230 50 100 200 400

5” Damper

45

40

35

6 5 4 3

2

1

7

50

30

25

dB (A)

L A.

q, cfm

Pt.

in W

G

2.00

1.00

0.50

0.20

0.10

0.05

0.026 10 20 50 100 200 250

4” Damper

45

40

356 5 4 3 2 17

s =

8

dB (A

)

L A.

IRIS DAMPER SELECTION CURVES

5

2.00

1.00

0.50

0.20

0.10

0.05

0.021000 2000 5000 10000500 16000

32” Damper

45

40

356 5 4 3 2 17

s =

8

50

55

60

dB (A

)

L A.

2.00

1.00

0.50

0.20

0.10

0.05

0.021000 2000500 5000 10000 14000

25” Damper

60

6

5 4 3 2 1

7

s =

8

dB (A

)

L A.

q, cfm

Pt.

in W

G

q, cfm

Pt.

in W

G

2.00

1.00

0.50

0.20

0.10

0.05

0.02300 1000 2000500 90005000

20” Damper

45

40

55

6 5 4

3

2

1

7

s =

850

dB (A

)

L A.

q, cfm

Pt.

in W

G

1.50

1.00

0.50

0.20

0.10

.0150.02

2000500 1000200 2500

16” Damper

25

30

35

6 5

4

3

2

1

7

s = 8

dB (A)

L A.

q, cfm

Pt.

in W

G

2.00

1.00

0.50

0.20

0.10

0.05

0.02160 200 500 1000 2000 2500

12” Damper

55

6 54

3

2

1

78

dB (A)

L A.

q, cfm

Pt.

in W

G

2.00

1.00

0.50

0.20

0.10

0.05

0.02500 1000 2000100 200

q, cfm

Pt.

in W

G

10” Damper

60

55

50

6 5

4

3

2

1

78

dB (A)

L A.

AIRFLOW ADJUSTMENT CHARTS

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Pm (In. wg)

q = k

pm = (q / k)2

pm

IRIS

Fig. 2

0.5” W.G. Position 6

Fig. 3

2.004567 3

2

1

1.50

1.00

0.500.400.30

0.20

0.10

0.050.040.030.02

20 30 40 50 70 100 150 200 300 400

P mIN

. WG

q, cfm

Damper position

5” DAMPER

K=462K=294

K=217

K=157K=117

K=90K=50

2.001.50

1.00

0.50

0.30

0.20

0.10

0.050.04

0.40

0.03

0.0210 15 20 30 40 50 60 80 100 150 200 250

1

2

345678

q, cfm

Damper position

P mIN

. WG

4” DAMPER

K=348K=251K=201

K=151K=114

K=84K=57

K=30

AIRFLOW CONTROL AND BALANCEOnce an IRIS damper has been installed and the system is operational,the damper may be adjusted to deliver required airflow using the airflowadjustment chart located on the damper. Airflow Adjustment Charts forIRIS and IRIS-S dampers are shown on pages 6 and 7.

Each IRIS damper contains two airflow taps (pressure ports) and an AirflowAdjustment Chart. By connecting a pressure gauge to the taps of thedamper, the pressure drop across the damper blades can be measured. Theillustration (Fig. 2) shows the setup for making a pressure measurement.

Each damper setting has a unique ‘k’ factor that defines the curves at differentdamper settings. The air velocity flowing through the orifice of the damperis proportional to the measured pressure drop. Once the velocity is known,the airflow can be easily calculated when the cross-sectional area of theorifice is known. The relationship between pressure drop and airflowthrough an IRIS damper is:

q = K √∆ρm

q = airflow (cfm)

Dpm = measured pressure drop (in. w.g.)

k = constant of proportionality

(dependent upon orifice area)

For initial airflow balance, note the damper position and related pressuredrop. Refer to the Airflow Adjustment Charts to determine the airflow.

To adjust to a new airflow, locate the desired airflow on the AirflowAdjustment Chart and adjust the damper position until the requiredpressure drop is achieved (Fig. 3).

AIRFLOW ADJUSTMENT CHARTS

7

P mIN

. WG

q, cfm

Damper position2.00

45673

2

1

1.50

1.00

0.500.400.30

0.20

0.10

0.050.040.03

0.022000 10000700 1000 1500 50003000 4000

8

15000

K=16355K=13445

K=11505K=8930

K=7258K=5686

K=4080K=245632” DAMPER

q, cfm

Damper position

P mIN

. WG

2.004567 3 2

11.50

1.00

0.500.400.300.20

0.10

0.050.040.030.02

10000400 600 1000 50002000 3000

8

16000

K=15084K=9933

K=7960K=5652

K=4248

K=3064

K=2100

K=1174

25” DAMPER

P mIN

. WG

q, cfm

Damper position2.00

4567 32

11.50

1.00

0.500.400.30

0.20

0.10

0.050.040.03

0.02700 5000300 400 500 40001000 2000 3000

8

8000

K=7693K=5920

K=4883K=3746

K=2960K=2227

K=1605K=100320” DAMPER

q, cfm

Damper position

P mIN

. WG

2.004567 3 2

11.50

1.00

0.500.400.30

0.20

0.10

0.050.040.030.02

400030001000150 2000500200 300 400

8

5000

K=4381K=3411

K=2953

K=2251

K=1763K=1288

K=950

K=51816” DAMPER

P mIN

. WG

q, cfm

Damper position2.00

4567

3

2

1.50

1.00

0.500.400.30

0.20

0.10

0.050.040.03

0.02700 1000150 500200 300 400

8

1500 2000 2500

K=2579K=2100

K=1559K=1254

K=1013

K=739K=51812” DAMPER

q, cfm

Damper position

P mIN

. WG

2.004567

32

1

1.00

1.50

0.500.400.30

0.20

0.10

0.050.040.03

0.02700150 1000250100 500200 300 400

8

1500

K=2154

K=1525

K=1294K=1027

K=806K=615

K=428K=29810” DAMPER

P mIN

. WG

q, cfm

Damper position2.00

4567 3 2

11.00

1.50

0.500.400.30

0.20

0.10

0.050.040.030.02

700150 100050 70 100 500200 300 400

8

1500

K=1478K=1033K=609

K=776

K=468K=368

K=281K=1678”

DAMPER

q, cfm

Damper position

P mIN

. WG

2.004567 3

2

1

1.50

1.00

0.50

0.300.40

0.20

0.10

0.050.040.03

0.0270030 40 50 70 100 500200 300 400

8

K=806K=552

K=448K=368

K=298

K=231K=174K=1246”

DAMPER

Industrial Fans& Blowers

Commercial Fans& Dampers

OEM Solutions& Custom Fans

Residential Fans & Air Puri�ers

Continental Fan Manufacturing Inc.Bu�alo, New York

Continental Fan Manufacturing Inc.Dayton, Ohio

Continental Fan Canada Inc.Mississauga, Ontario

1-800-779-4021 • www.continentalfan.com

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Iris Damper Application Guide

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