Ceiling Radiation Damper Model CRDD
The Model CRDD damper is described as a rectangular butterfly style damper mounted in the base of a register-box plenum (boot). The damper blades and frame are constructed with G60 roll-formed galvanized steel with minimum thickness of 24 GA. The blades are insulated with nominal 1/4-in., 8-lb/ft
3 (128 kg/m
3) ceramic fiber insulation. The damper is held open with a 212 °F fusible link and closes by a spring force. The maximum damper size shall be of 256 in.
2 with no dimension greater than 16 in.
The register-box plenum has two options for the construction material. One option is construction with steel and second option is construction with duct-board. The steel register-box plenum is constructed with G60 galvanized steel, maximum thickness of 24 GA and minimum thickness 28 GA. As an option for the steel register-box plenum, the register-box plenum can be insulated with 1-in. thick, fiberglass insulation with a minimum R-value of 4.2. The duct-board register-box plenum is constructed with minimum thickness 1-in. duct-board, with a minimum R-value of 4. The joints and seams shall be per Royal Metal Products installation instructions.
For damper sizes greater the 144 in.
2 with a maximum dimension of 16 in., the duct-board plenum is required. Minimum clearance to combustibles is 4 in. for the steel plenum and 1 in. for the duct-board plenum.
The Royal Metal Damper models using this design are the 557RD, 557RDD, 556RD, 556RDD, 241FRD, 241RD, 243FRD, and 243RD.
Royal Metal 557RD and 557RDD
The 557RD and 557RDD uses a register-box plenum constructed of duct board, with minimum thickness 1-in. duct board with a minimum R-value of 4. The 557RDD is designed for installation in the ceiling and uses with a register. The 557RDD has a damper sleeve that extends below the ceiling for duct connection to the air handler.
Royal Metal 556RD and 556RDD
The 556RD uses a steel register-box plenum with round connection collars on the side of the plenum. The 556RDD has a damper sleeve that extends below the ceiling for duct connection to the air handler.
Royal Metal 241FRD and 241RD
The 241FRD and 241RD uses a steel register-box plenum with round connection collars on the top of the plenum. The 241FRD plenum has a frame around the bottom to facilitate installation with boot rails. The 241RD has no frame and requires installation with a minimum 3/4- × 3/4-in. × 16-GA angle.
Royal Metal 243FRD and 243RD
The 243FRD and 243RD uses a steel register-box plenum with tapered connection that turns 90° into the round collars out the side of the plenum. The 243FRD plenum has a frame around the bottom to facilitate installation with boot rails. The 243RD has no frame and requires installation with a minimum 3/4- × 3/4-in. × 16-GA angle.
Ceiling Radiation Damper Model CRDS
The Model CRDS is described as a rectangular single-blade damper. The construction and boot requirements are identical to the CRDD. The only difference is the CRDS is a single blade damper with a maximum size of 144 in.
2 with a maximum dimension of 14 in.
The Royal Metal Damper model using this design are the 241FRD, 241RD, 243FRD, 243RD, 509RD, and 557RD, and 556RD. The 241FRD, 241RD, 243FRD, 243RD, 557RD, and 556RD models are described with Ceiling Radiation Damper Model CRDD.
Royal Metal 509RD
The Royal Metal Model 509RD is an insulated steel plenum with a duct connection on the side.
Ceiling Radiation Damper Model CRDR
The Model CRDR damper is described as circular butterfly style damper mounted in the duct connection collar. The damper blades and frame are constructed with G60 roll-formed galvanized steel with minimum thickness of 24 GA. The blades are insulated with 1/4-in., 8-lb/ft
3 (128 kg/m
3) ceramic fiber insulation. The damper is held open with a 212 °F fusible link and closes by a spring force. The duct connection collar is round, for nominal duct sizes from minimum 4-in. to maximum 10-in. diameter and is dependent on the grille size.
The insulated register-box plenum (boot) is constructed with maximum thickness of 24 GA and minimum thickness 28 GA, G60 galvanized steel with a round duct top inlet. The nominal height off the boot and collar is 7-1/2 in. and is in sizes for a rectangular opening for steel grille sizes ranging from 8- × 4-in., minimum, to 14- × 8-in., maximum. The inside of the register-box plenum has minimum 1-in. thick fiberglass insulation with a minimum R-value of 4.2.
The Royal Metal Damper models using this design are the 505RD and 507RD.
Royal Metal 505RD
The 505 designates a register-box plenum configured with the duct connection on top with the damper contained within the duct connection collar. The duct connection is parallel to, and center with the grille.
Royal Metal 507RD
The 507 designates a register-box plenum with the duct connection configured 45° offset relative to the grille inlet with the damper contained within the duct connection collar.
| Test Standard |
Rating |
Design Number |
| ASTM E119 / UL 263 |
1-hr |
RMP/DA 60-02 |
