Daniel Company | Ductwork & Accessories
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Ductwork & Accessories


Daniel Mechanical offers corrosion and flame resistant ductwork and pipe.


Daniel Mechanical duct and pipe are fabricated from fiber reinforced plastics using hand lay-up and random chop filament winding methods.


A superior product is guaranteed by strict adherence to NBS PS 15-69 dimensional and quality control standards.


Daniel Mechanical is uniquely equipped to install, balance, and performance test complete exhaust and supply air systems. Certified technicians are proficient in training installer crews on the job site in FRP field jointing and installation techniques.

Ductwork Designed Properties:

  • Above & below grade filament wound pipe built to H-20 live load calculations in diameters ranging from 4″Ø to 84″Ø.



Standard Fittings:

  • round and rectangular elbows with long and short radius, transitions, flanges, end caps, tees, wyes, and laterals


Custom sized rectangular duct and related fittings are available with composite materials and stiffeners where required for structural integrity.


DanELAST Bubble-Tight Dampers


Daniel Company offers precision-engineered fiberglass reinforced plastic bubble-tight DanELAST isolation dampers utilizing only highly corrosion resistant parts for air movement and controls.


Bubble-tight DanELAST dampers are fire retardant, corrosion resistant, and UV protected. All components are designed with replaceable parts that are easily disassembled for maintenance. The blade shafts are constructed of custom-milled, solid 316SST metal. Daniel Mechanical Company’s bubble-tight DanELAST damper utilizes a specially formulated elastomer with corrosion resistance equal to and/or superior to EPDM, Hypalon, and even Viton.

No circumferential blade seals are required to achieve a full shutoff of the bubble-tight DanELAST isolation damper. This is largely due to the innovative design and expert hand craftsmanship of each key part. By constructing the unitary FRP blade to exact tolerances and without a commonly used circumferential blade seal, the weakest part of the damper is eliminated, thus improving its reliability. No blade stops are utilized, decreasing the pressure loss across the damper when in the full open position. Each bubble-tight DanELAST damper is factory tested to operating pressures exceeding 30 inches w.g. Leakage rates are tested using AMCA 500-D procedures, and the certified ratings are authorized by AMCA.


The bubble-tight DanELAST damper blade is operated using a hand-wheel driven worm gear operator. Pneumatic, electric, or chain-wheel type operators are optional. Long life Teflon bearings and extensively tested molded plastic bushings accessible from the exterior of the damper require minimal maintenance and ensure unrestricted movement of the rotating shaft. All metal parts in contact with process air stream are at a minimum 316 stainless steel and may be manufactured of more exotic metals such as Hastelloy-C and Titanium.


Bubble-tight DanELAST dampers enhance safety by providing greater isolation of process air during shutdown of low pressure exhaust system duct lines conveying hazardous air streams. When dealing with confined space entry conditions, use of bubble-tight DanELAST isolation dampers may reduce safety risks caused by contaminant air leaks.


Bubble-tight DanELAST isolation dampers require far less maintenance, are more durable, and outperform conventional butterfly dampers. Bubble-tight DanELAST dampers range in sizes from 4-inch diameter to 120-inch diameter.

Standard Construction
Frame Vinyl ester resin fabricated to ASME/ANSI RTP-1
Flange  NBS PS 15-69-3.4.7 ¾” thick, hand lay-up integral to body per ASME RTP-1-2000 Standard Fig. 4-7.
Blade Vinyl ester resin similar to damper frame. Unitary construction with no circumferential seal or backstop, having a calculated percent deflection of L/360
Stiffeners Same material as frame and integrally molded to blade
Shaft 316 SST with nuts, bolts, and washers (FRP encapsulated if required)
Shaft Seal Externally adjustable compression type with FRP housing and Viton O-ring 
Bearing Teflon
Operator Worm gear with hand wheel, chain wheel, pneumatic, or electric actuation
Gel Coat Paraffinated, with ultraviolet inhibitor
Color White unless specified otherwise
Maximum Temperature 200°F
Maximum Pressure 30” w.g.
Maximum Leakage  Zero cubic feet per minute per square-foot of cross sectional area
Lubricant  None required

Top View:

Size I.D.Flange Thickness (Min.)Flange O.D.Bolt Circle Dia.Bolt Hole Dia.# of Bolt HolesBlade ThicknessAxle Dia."A""B"Damper Width
4" 3/4" 8 3/8" 7" 7/16" 4     5" 6" 6"
6" 3/4" 10 3/8" 9"  7/16" 8     6" 8" 6"
8" 3/4" 12 3/8"  11" 7/16" 8     6" 8" 6"
10" 3/4" 14 3/8" 13" 7/16" 12     6" 8" 12"
12" 3/4" 16 3/8"  15"  7/16" 12'     6" 8" 12"
14" 3/4" 18 3/8"  17" 7/16" 12     6" 8" 12"
16" 3/4" 20 3/8"  19"  7/16" 16     6" 8" 12"
18" 3/4" 22 3/8" 21" 7/16" 16     6" 8" 12"
20" 3/4" 24 3/8" 23" 7/16" 20     6" 8" 12"
24" 3/4" 28 3/8"  27" 7/16" 20     7.5" 8" 12"
30" 3/4" 34 3/8"  33" 7/16" 28     7.5" 8" 12"
36" 3/4" 40 3/8" 39" 7/16" 32     7.5" 8" 12"
42" 3/4" 46 3/8"  45" 7/16" 36     7.5" 8" 12"
48" 3/4" 54 3/8"  52" 9/16" 44     7.5" 8" 12"
54" 3/4" 60 3/8"  58" 9/16"  44     10" 8" 12""
60" 3/4" 66 3/8"  64" 9/16"  52     10" 8" 12""
72" 3/4" 79" 76" 9/16" 64     12" 12" 18"

Suggested  Specifications for Round FRP Air Control Dampers
Dampers are installed as shown on plans and per specifications. Damper frame shall be of one-piece construction with a resin rich interior corrosion barrier having a minimum thickness of 100 mils. A structural wall shall consist of alternate layers of chopped strand mat and woven roving to conform to ASME/ANSI RTP-1 and NBS PS 15-69. The overall glass and resin content shall be 40% and 60% by weight, respectively.The fiberglass flange dimensions shall be per NBS PS 15-69 Table 2 for dimensions and bolthole drilling pattern.

The flanges shall have a minimum thickness of 3/4 inch and shall be constructed integral to the cylindrical body of the damper, using the hand lay-up technique per ASME RTP-1-2000 standard Fig 4-7. The distance between the faces of the flanges shall be 6 inches for dampers having a diameter size of 8 inches or less. For all other damper sizes, this distance shall be 12 inches long. The damper blade and stiffeners shall be fabricated using the same resin as the damper frame. The damper blade shall be of unitary construction having no detachable parts or circumferential or wiper blade seals. Damper blade shall be designed to prevent over-rotation without the use of backstops located anywhere in the air stream. 316 SST blade shaft shall be continuous, centered, and custom-milled to fit the operator. Both the damper blade and shaft shall be fully detachable from each other and readily disassembled from the damper body for easy repair or maintenance.

Damper shall have an FRP structural stand-off bracket integrally laminated to the exterior of the body for mounting a worm gear operator.

Damper shall be provided with a self-lubricated hand-wheel driven worm gear operator, as manufactured by:

  • Dynatorque, or equal

Operator shall be sized according to required operating torque. Operator shall be coated with corrosion resistant epoxy. All metal parts exposed to the air stream shall be 316 SST. All zero-leakage dampers located at elevations exceeding 6’-6” above finished floor shall, in addition to the hand wheel, be equipped with chain wheel sprockets and appropriately sized chain lengths, as manufactured by:

  • Babbitt, or equal

Chain wheel sprockets shall have integral chain guides to prevent “gagging”.

Annular DanELAST corrosion resistant elastomer sealing seat shall be embedded in the damper body to achieve zero leakage.

Exterior surface of damper shall contain UV inhibitor, and be gel coated or painted with color to match existing ducting.

FRP dampers shall be tested for pressure drop and leakage in accordance with AMCA Standard 500-D. AMCA 500-D leakage tests shall be performed by AMCA certified testing facilities. The leakage rate shall be a maximum of 0 C.F.M per square-foot of cross-sectional area at 30-inches w.g. pressure. The test results shall be submitted for review and approval by the Engineer. The zero-leakage damper shall bear the AMCA seal.

Approved manufacturer of zero-leakage isolation damper shall be:

  • Daniel Mechanical – Model: DanELAST 303
  • Or equal
Certified Ratings Authorized by AMCA
amca logoDamper DiameterTorque in lbs.Leakage ClassBlade Fixed Open
AP (in. wg)CFM
4" 66 1A - -
12" 891 1A 0.11 1,983
24" 486 1A 0.04 6,585
36" 360 1A 0.03 14,072
48" 464 1A - -
54" 630 1A - -
60" 866 1A - -
72" 360 1A - -
Daniel Mechanical Company certifies that the Model 303 dampers shown herein are licensed to bear the AMCA Seal. The ratings shown are based on tests and procedures performed in accordance with AMCA Publication 511 and comply with the requirements of the AMCA Certified Ratings Program. The AMCA Certified Ratings Seal applies to air performance and air leakage ratings.
Test method is per AMCA Standard 500-D-98 Figures 5.3, 5.4 Alternate-6.3, 5.5, & 5.6, 6.5. Data are based on a seating torque of chart listed in-lbsapplied to hold the damper in the closed position. Air leakage is based on operation between 50°F – 104°F.

Model 203 Air Control Damper


Daniel Company also offers Model 203 traditional style dampers. Model 203 dampers use a seal that is attached to the blade with fiberglass stops embedded into the body.


The Model 203 offers precision-engineered FRP butterfly dampers utilizing only highly corrosion resistant parts for air movement and controls. Dampers are fire retardant, corrosion resistant, and UV protected. Components are designed with replaceable parts for ease of disassembly. The options of having 316 SST or FRP blade shafts are available. Additionally, exotic and corrosion resistant elastomers such as Viton, Hypalon or EPDM may be selected depending on the process. Blades are equipped with circumferential seals for low leakage.


Leakage rates are tested using AMCA 500 procedures and the certified ratings are authorized by AMCA. Damper blade is operated using hand lever with locking quadrant. Worm gear operators of the pneumatic, electric or hand-operated with chain-wheel types are also offered. Long life Teflon bearings and custom-designed molded plastic bushings, located on the exterior of damper, require minimal maintenance and ensure continuous free movement of the blade. Stops, (stiffeners as required), are used to support and seat the FRP blade. All metal parts are at a minimum 316 stainless steel. Dampers range from sizes 4” diameter to 60” diameter.

DanFLEX Flexible Connectors


Provide superior absorption of lateral, torsional, angular, and axial movement experienced in rigid ducting/piping systems.


DanFLEX is constructed of vulcanized layers of polyester tire-cord fabric reinforcement, sandwiched between a 60 to 70 durameter elastomeric inner liner and exterior cover. Tire-cord fabric is layered at an optimal bias angle with Resorcinol Formaldehyde Latex for superior rubber-to-fabric bonding. The elastomer is built as one continuous piece with an integrally molded, hollow-arched volute. 316 stainless steel retainer bands are used with adjustable screw seal type fasteners. DanFLEX is suitable for use in H2S-laden, corrosive environments, and is resistant to ultra violet rays.

Features Superior Flexibility

DanFLEX flexible connectors provide superior absorption of lateral, torsional, angular, and axial movement experienced in rigid ducting/piping systems due to thermal expansion and contraction, installation misalignment, and vibration.


Eliminates High Stress Points

The weakest point of a traditional flexible connector design is located annularly – where the back of the integrally molded elastomer flange meets the tubular section. DanFLEX relieves this high stress area by overlapping the tubular elastomer onto the hubs of the FRP flanges.


Infinite Bolt Hole Alignment Capability

DanFLEX flexible connector is designed to allow for infinite adjustment capability to accommodate any degree of axial misalignment of bolt holes.



Simpler and Easier to Replace

The elastomer portion of the DanFLEX flexible connector is an off-the-shelf commodity item. All parts of DanFLEX are pre-engineered, made to standard sizes, and are interchangeable. As a result, replacement lead time is reduced. Furthermore, in the event that the mating equipment is modified and requires a different bolt-hole pattern, the flange can easily be replaced without having to change out the entire flexible connector.

Withstands Extreme Torsional Forces

DanFLEX flexible connector is designed to absorb extreme and sudden torsional forces without wrinkling and (eventually) cracking of the molded elastomer volute. As an intended fail-safe feature, if excessive twisting forces are applied to the fl ex connector, the flanges will slip inside the tubular elastomer sleeve instead of tearing it.

Facilitates Accurate Installation

DanFLEX has an adjustable overall length, facilitating a more accurate fi t and finish when installing in parent duct/pipe spools which have finite length measurements. This is easily achieved by extending the length of either of the FRP flanged stubs located at each end of the flexible connector.

Longer Warranty Period

Daniel Company’s DanFLEX flexible connector comes with double the warranty period offered by other manufacturers.

Suggested Specifications for Round Flexible Connectors

Flexible connectors shall be provided wherever indicated. To maintain overall system responsibility by a singular source, all flexible connections shall be supplied by the MANUFACTURER of the FRP duct/ pipe. Acceptable flexible connector is DanFLEX Model 101 as manufactured by Daniel Company, or equal.

Flexible connectors are intended to be used in rigid duct/pipe systems for lateral, torsional, angular and axial movement due to expansion, contraction, and vibration. Product may be utilized to compensate for minimal misalignment. Construction shall be of multiple layers (2 minimum) of vulcanized polyester tire-cord fabric reinforcement, sandwiched between 60 to 70 durometer elastomer inner liner and exterior cover. Use of reprocessed/ reclaimed rubber is not acceptable. Tire-cord fabric will be layered at an optimal bias angle with Resorcinol Formaldehyde Latex for superior rubber-to-fabric bonding.

Seamless construction, built as one continuous piece with integral molded hollow arched volutes, shall permit up to a total of 4” of axial contraction and expansion.

Flexible connectors shall be designed to allow for a minimum of 1” of offset movement in any direction. No wrap, seamed or spliced type flexible connectors will be allowed.

Flanges shall be of FRP construction per NBS PS 15-69- 3.4.7. Bolt-hole pattern shall fi t that of mating duct/pipe or equipment.

316 SST retainer bands shall be used with adjustable screw seal type fasteners. All hardware and materials of construction shall be suitable for H2S laden corrosive environment and able to resist UV rays.

Connector Dimensions

Size I.D.Flange Thickness (Min.)Flange O.D.Bolt Circle Dia.Bolt Hole Dia# of Bolt HolesFlange Flex Connector Length (Nom.)
4"  3/4" 8 3/8" 7"  7/16"  4 12" 
6"  3/4"  10 3/8" 9"  7/16" 8 12"
8"  3/4" 12 3/8"  11"  7/16" 8 12"
10" 3/4" 14 3/8" 13" 7/16" 12 12"
12" 3/4" 16 3/8"  15"  7/16" 12' 12"
14" 3/4"  18 3/8"   17" 7/16" 12 12"
16"  3/4" 20 3/8"  19"  7/16" 16 12"
18"  3/4"  22 3/8"  21" 7/16" 16 12"
20"  3/4"  24 3/8"  23" 7/16" 20 12"
24"  3/4" 28 3/8"  27"  7/16" 20 12"
30"  3/4" 34 3/8"  33"  7/16" 28 12"
36"  3/4"  40 3/8"  39" 7/16" 32 18"
42"  3/4" 46 3/8"  45"  7/16" 36 18"
48"  3/4" 54 3/8"  52" 9/16" 44 18"
54"  3/4" 60 3/8"   58" 9/16"  44 18"
60"  3/4" 66 3/8"  64"  9/16"  52 18"
72"  3/4" 79"   76" 9/16" 64 18"

Approved manufacturer of flexible connectors shall be:

  • Daniel Company – DanFLEX Model 101