Greenheck VCD-20 Control Damper - 3V Blade

Product Overview and Technical Specifications

Application

The VCD-20 series is a general purpose control damper designed for applications requiring automatic control or manual balancing in low to medium pressure and velocity systems.

Damper Ratings

Velocity: Up to 3000 fpm (15.2 m/s)

Pressure: Up to 5 in. wg (1.2 kPa) - pressure differential

Temperature: -40°F to 250°F (-40°C to 121°C). Consult factory for specific temperature requirements.

Construction

Feature	Standard	Optional
Frame Material	Galvanized Steel	304SS
Frame Material Thickness	16 ga. (1.5 mm)	12 ga. (2.7 mm)*
Frame Type	5 in. x 1 in. hat channel; Single flange, Reversed flange, Double flange
Blade Material	Galvanized steel	304SS
Blade Thickness	16 ga. (1.5mm)
Blade Type	3V
Blade Action	Opposed	Parallel
Linkage	Plated steel out of airstream, concealed in jamb
Axle Bearings	Synthetic	316SS
Axle Material	1/2 in. dia. Plated steel	316SS
Paint Finishes	Mill Finish	Baked Enamel, Hi Pro Polyester, Industrial Epoxy

*Note: When 12 ga. frame is selected and the damper height is less than 17 inches, low profile top and bottom frame members are utilized. These low profile frame members will be made from 16 ga. material.

*Note: W & H dimensions are furnished approximately 1/4 in. (6mm) undersize.

Dimensions

Size	Minimum Size	Maximum Size (Single Section)	Maximum Size (Multiple Section)
W x H (Inches)	6 x 6	48 x 74	Unlimited
W x H (mm)	152 x 152	1219 x 1880	Unlimited

Blade Operation

The damper blades can operate in two configurations:

Parallel Blades: Blades move in the same direction. Illustrated with a 5-inch (127mm) blade width.
Opposed Blades: Adjacent blades move in opposite directions. Illustrated with a 5-inch (127mm) blade width and a 1 1/4 inch (32mm) maximum typical dimension.

Notes

Low profile head and sill are used on sizes less than 17 in. (432mm) high.
Linkage is concealed within the frame.
Electric actuators and manual quadrants are available. Factory-supplied actuators are rated for 1500 fpm (7 m/s) and a fully closed differential pressure of 2 in. wg (0.5 kPa). Contact the factory for actuator sizing on applications exceeding these limits.
In applications with uneven airflow, such as discharge fans, it is imperative to verify that the maximum velocity does not exceed the damper's cataloged velocity at any point.
Blades must be horizontal for either horizontal or vertical mounting. For vertical blades, consult the VCD-23V model.

Options

Actuators (24V, 120V, manual, pull chain)
Actuator mounting (external, external kit (field assembly), internal)
Flanges
Multi-section fastening
NEMA enclosures (3, 4, 4X, 7)
OCI (open or closed indicator)
R Transition
Retaining angles
Security bars
Sleeves
Transformers

Flange Configurations

The VCD-20 damper is available in several flange configurations for mounting:

Single Flange: Features a flange on one side of the damper frame. Illustrated with a 5-inch (127mm) dimension.
Reversed Flange: Features a flange on the opposite side of the primary frame. Illustrated with a 5-inch (127mm) dimension.
Double Flange: Features flanges on both sides of the damper frame. Illustrated with a 5-inch (127mm) dimension and a 1 1/2 inch (typical) dimension.

*Note: Diagrams shown with optional internally mounted actuator.

AMCA Certified Pressure Drop Data

Greenheck Fan Corporation certifies that the model VCD-20 is licensed to bear the AMCA Seal. Ratings are based on tests and procedures performed in accordance with AMCA Publication 511 and comply with the requirements of the AMCA Certified Ratings Programs. The AMCA Certified Ratings Seal applies to Air Performance ratings.

The following tables provide pressure drop data for various sizes and airflow velocities, categorized by AMCA standards (5.2, 5.3, 5.5).

AMCA 5.2

Size (in.)	12 x 12 (305 x 305)		24 x 24 (610 x 610)		36 x 36 (914 x 914)		12 x 48 (305 x 1219)		48 x 12 (1219 x 305)
Size (in.)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)
500	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
1000	0.05	0.03	0.02	0.04	0.03	0.03	0.04
1500	0.11	0.06	0.05	0.08	0.07	0.07	0.08
2000	0.19	0.10	0.09	0.15	0.12	0.12	0.15
2500	0.29	0.16	0.14	0.22	0.18	0.18	0.22
3000	0.41	0.23	0.19	0.32	0.26	0.26	0.32
3500	0.55	0.30	0.27	0.43	0.36	0.36	0.43
4000	0.72	0.40	0.35	0.56	0.47	0.47	0.56

AMCA 5.3

Size (in.)	12 x 12 (305 x 305)		24 x 24 (610 x 610)		36 x 36 (914 x 914)		12 x 48 (305 x 1219)		48 x 12 (1219 x 305)
Size (in.)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)
500	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01	0.01
1000	0.03	0.02	0.02	0.03	0.03	0.03	0.03
1500	0.08	0.04	0.03	0.07	0.06	0.06	0.07
2000	0.13	0.07	0.06	0.12	0.10	0.10	0.12
2500	0.20	0.11	0.09	0.18	0.16	0.16	0.18
3000	0.29	0.16	0.13	0.26	0.22	0.22	0.26
3500	0.40	0.21	0.19	0.36	0.30	0.30	0.36
4000	0.51	0.28	0.25	0.46	0.39	0.39	0.46

AMCA 5.5

Size (in.)	12 x 12 (305 x 305)		24 x 24 (610 x 610)		36 x 36 (914 x 914)		12 x 48 (305 x 1219)		48 x 12 (1219 x 305)
Size (in.)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)	Velocity (fpm)	Pressure Drop (in. wg)
500	0.03	0.03	0.02	0.03	0.03	0.03	0.03
1000	0.13	0.12	0.10	0.14	0.12	0.12	0.14
1500	0.30	0.26	0.22	0.32	0.28	0.28	0.32
2000	0.53	0.47	0.40	0.57	0.49	0.49	0.57
2500	0.82	0.75	0.62	0.90	0.77	0.77	0.90
3000	1.19	1.04	0.90	1.29	1.12	1.12	1.29
3500	1.62	1.41	1.23	1.76	1.53	1.53	1.76
4000	2.10	1.90	1.62	2.30	2.01	2.01	2.30

Leakage Data

Leakage testing was conducted in accordance with AMCA Standard 500-D and is expressed as cfm/ft² of damper face area. Data is corrected for standard air density (0.075 lb/ft³ or 1.204 kg/m³).

Leakage Graph: A log-log graph illustrates the relationship between Static Pressure Difference (in. wg) on the y-axis and Air Leakage (cfm/ft²) on the x-axis. The data shows a positive correlation, with leakage increasing as static pressure rises.

Velocity Limitations Graph: This chart displays velocity limitations based on damper dimensions. The y-axis represents Damper Height (in.) and the x-axis represents Damper Width (in.). Shaded regions indicate maximum allowable velocities: 3000 fpm for smaller dampers, 2500 fpm for intermediate sizes, and 2000 fpm for larger sizes.

Space Envelopes and Clearance Requirements

Space Envelopes: For dampers less than 18 inches (457mm) high, specific clearances (labeled 'T' for top, 'B' for bottom, and 'D' for side) may be required for actuator mounting. These are worst-case requirements for some dampers and should be evaluated based on individual space availability. The table lists these clearances for various actuator types and height ranges.

Clearance Requirements (Internal Mount): A diagram illustrates the typical clearance requirements for actuators mounted internally with a jackshaft. It details dimensions A, B, and C for different actuator models, including the EFB & EFCX Series and other models.

Actuator Model	Height (Inches/mm)	B (Inches)	D (Inches)
AFBUP (-S) and FSNF Series, Belimo MSxx20 Series, Honeywell	>6 to <10	12³⁄₄	6
	>10 to <18	2	6
	≥18	0	10
FSLF, LF and TFB Series, Belimo	>6 to <10	3¹⁄₂	6
	≥10	0	6
MSxx04 & MSxx09 Series, Honeywell	>6 to <9	4³⁄₄	6
	≥9	0	6
MS75xx Series, Honeywell	>6 to <10	12³⁄₄	6
	>10 to <18	7	6
	≥18	0	6

Internal Mount Clearance Requirements

Actuator Model	A (Inches/mm)	B (Inches/mm)	C (Inches/mm)
All except - EFB & EFCX Series	7 3/4 in (197 mm)	3 3/4 in (95 mm)	5 3/8 in (136.5 mm)
EFB & EFCX Series	8 1/2 in (216 mm)	6 in (152mm)	8 1/2 in (216 mm)

The diagram for internal mount clearance shows a typical actuator installation with a jackshaft, indicating dimensions A, B, and C relative to the damper frame and actuator.

Actuator Mounting

Actuators can be installed at the factory, shipped loose with necessary linkage and brackets, or supplied by the field. For detailed information on actuator mounting, refer to the provided link or scan the QR code.

Actuator Mounting Diagram: An illustration shows a "Non-jackshaft external right" mounting configuration, where an actuator is attached externally to the right side of the damper frame.

Multi-Section Dampers

Dampers larger than the maximum single section size (48 in. x 74 in. or 1219mm x 1880mm) are constructed from multiple equal-sized sections. These larger multi-section dampers are not intended to be structurally self-supporting. Refer to IOM document 463384 for structural support requirements on multi-section assemblies.

Multi-Section Damper Diagrams:

One diagram shows a 2-section damper example driven by a single jackshaft.
Another diagram illustrates a larger configuration, 6 sections wide and 3 sections high, where each section is driven by an individual actuator.

Document Links

Access additional resources for the VCD-20 damper:

Installation Guide
Catalog
Selection Guide
Specifications
Warranty Information

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