Field Dictionary

Access door

Also called: Access panel, inspection door, cleanout door

Removable panel for inspection/cleaning.

Balancing damper

Also called: BD, manual balancing damper

Manually adjusted for airflow balance.

Beam attachment

Also called: Beam clamp, beam hanger

General beam hanger attachment.

Beam clamp

Also called: C-clamp, beam attachment, structural clamp

Clamps to steel beam for hanger.

Branch line

Also called: Branch duct, runout, tap line

Duct branching from trunk.

CFM

Also called: Cubic feet per minute, airflow

Airflow volume measurement.

Clevis hanger

Also called: Clevis, U-hanger, pipe hanger

U-shaped hanger for round pipe.

Combination fire/smoke damper

Also called: FSD, fire/smoke damper

Combined fire and smoke protection.

Combination square

Also called: Combo square, speed square

Multi-purpose measuring and layout tool.

Crimp

Also called: Crimped end, reduced end, swage

Reduced end for fitting into next section.

Crimp and slip joint

Also called: Crimp joint, reduced end joint

Crimped end slips into next section.

Cut list

Also called: Bill of materials, BOM, takeoff list

List of pieces to be fabricated.

Damper blade

Also called: Blade, vane, damper vane

Moving part that closes damper.

Damper frame

Also called: Frame, housing, sleeve

Outer frame containing damper.

Damper schedule

Also called: Damper list, damper table

List of all dampers on project.

Damper sleeve

Also called: Sleeve, duct sleeve, damper housing

Duct section housing damper.

Damper testing

Also called: Damper operational test, functional test

Verifying damper operation.

Developed length

Also called: Stretch-out, blank length

Flat pattern length before forming.

Diffuser

Also called: Ceiling diffuser, supply diffuser, air diffuser

Air outlet with engineered airflow pattern.

Draw band

Also called: Clamp band, connection band, duct band

Metal band for sealing round duct joints.

Draw band joint

Also called: Band joint, clamp joint

Sealed with draw band.

Drive cleat

Also called: Drive, drive slip, S-drive

Slip used with S-cleat for transverse joints.

Drive cleat joint

Also called: Drive slip joint, drive connection

Uses drive cleat with S-cleat.

Duct collar

Also called: Neck, starter collar, connection collar

Rim for connecting duct to equipment or fittings.

Duct connector

Also called: Duct joint, connection piece

General connector piece.

Duct gauge

Also called: Metal gauge, sheet thickness

Thickness of sheet metal (e.g., 26 ga, 24 ga).

Duct joint sealer

Also called: Joint compound, sealing putty

Putty-like sealant for joints.

Duct leakage

Also called: Air leakage, leakage rate

Amount of air escaping duct.

Duct pressure class

Also called: Pressure rating, static pressure class

Rated pressure (e.g., 2-inch wg, 4-inch wg).

Duct sealer

Also called: Sealing compound, joint sealer

General term for duct sealant.

Duct section

Also called: Section, piece, length

Single piece of duct between joints.

Duct tape

Also called: Foil tape, aluminum tape, UL tape

Tapes seams and joints.

Elbow

Also called: Ell, bend, sweep

Direction change fitting.

Fire damper

Also called: FD, fire-rated damper, fusible link damper

Closes when temperature exceeds rating.

Fire damper inspection

Also called: FD inspection, damper test

Testing fire damper operation.

Fire damper installation

Also called: FD install, damper setting

Process of installing fire damper.

Fire rating

Also called: Hour rating, fire resistance rating

Duration of fire resistance (e.g., 1.5 hr, 3 hr).

Fire/smoke wall penetration

Also called: Wall penetration, fire wall sleeve

Duct through fire-rated wall.

Firestop

Also called: Fire stopping, fire seal, penetration seal

Seals penetration for fire rating.

Firestop caulk

Also called: Fire caulk, rated caulk

Fire-rated sealant.

Flange

Also called: Duct flange, mounting flange

Rim for bolting duct sections together.

Flange bolt

Also called: Carriage bolt, TDC bolt

Bolts for flange connections.

Flange gasket

Also called: Gasket, flange seal, rubber gasket

Seals between flanged joints.

Flange nut

Also called: Hex nut

Nuts for flange bolts.

Flanged connection

Also called: Flange joint, bolted flange

Bolted flange connection.

Flat S-cleat

Also called: Flat S, S-cleat, flat slip

Horizontal S-shaped cleat for transverse joints.

Floor penetration

Also called: Floor sleeve, shaft penetration

Duct through fire-rated floor.

Fusible link

Also called: Fusible element, thermal link, melt link

Melts at set temperature to close damper.

Fusible link rating

Also called: Temperature rating, melt temperature

Temperature at which link melts (e.g., 165°F, 212°F).

Gauge

Sheet metal thickness.

Grille

Also called: Register grille, return grille, eggcrate

Fixed blade air outlet/inlet.

Intumescent sealant

Also called: Fire caulk, intumescent

Expands when heated to seal gaps.

Mastic

Also called: Duct mastic, sealant mastic, pookie

Paste sealant for duct joints.

Neck size

Also called: Neck, connection size, inlet size

Duct connection size of diffuser.

Pipe crimper

Also called: Crimping tool, pipe swager

Crimpes end of round pipe.

Pipe diameter

Also called: Duct diameter, nominal diameter, OD/ID

Size specification for round duct.

Pipe gauge

Also called: Duct gauge, wall thickness

Thickness of round duct material.

Pipe support

Also called: Pipe hanger, duct support, clevis hanger

Support for round duct.

Pittsburgh joint

Also called: Pittsburgh seam joint

Longitudinal seam joint.

Pittsburgh Seam

Also called: Pittsburgh joint

Primary seam for rectangular duct longitudinal joints.

Pittsburgh seam connection

Also called: Pittsburgh joint

Uses Pittsburgh lock for joint.

Plenum

Also called: Supply plenum, return plenum, air chamber

Large chamber for air distribution.

Pressure drop

Also called: PD, pressure loss, resistance

Pressure loss through diffuser.

Reciprocating saw

Also called: Sawzall, recip saw, hackzall

Power saw for cutting pipe in place.

Rectangular duct

Also called: Square duct, box duct, trunk line

Primary duct shape in commercial HVAC.

Register

Also called: Supply register, floor register, wall register

Grille with integral damper.

Return air grille

Also called: Return grille, RA grille

Grille for return air intake.

Rod hanger

Also called: Beam clamp hanger, rod attachment

Attaches rod to structure.

Round elbow

Also called: Pipe elbow, bend, sweep

Direction change for round duct.

Round fire damper

Also called: Fire damper, FD

Fire-rated damper in round duct.

Round smoke damper

Also called: Smoke damper, SD

Smoke-rated damper in round duct.

Round volume damper

Also called: Butterfly damper, round damper

Damper in round duct.

S-cleat joint

Also called: S-slip joint, flat S joint

Uses flat S-cleat for transverse joint.

Saddle tap

Also called: Saddle, tap-in, welded saddle

Fitting welded/attached to side of duct for branch.

Seal class

Also called: Duct seal class, leakage class

SMACNA seal class (A, B, C).

Self-piercing screw

Also called: Zip screw, self-driller, tek-type screw

Drills own hole in sheet metal.

Sheet metal screw

Also called: SMS, tapping screw, self-tapping screw

General sheet metal fastener.

Shop drawing

Also called: Fabrication drawing, detail drawing

Detailed drawing for fabrication.

Slip and drive connection

Also called: S\&D connection, slip and drive

Common rectangular duct joint method.

SMACNA standards

Also called: SMACNA, HVAC duct construction standards

Sheet Metal and Air Conditioning Contractors' National Association standards.

Smoke damper

Also called: SD, smoke-rated damper

Closes to prevent smoke spread.

Smoke damper inspection

Also called: SD inspection, smoke damper test

Testing smoke damper operation.

Smoke damper installation

Also called: SD install, smoke damper setting

Process of installing smoke damper.

Smoke detector

Also called: Duct smoke detector, SD

Detects smoke in ductwork.

Snap-lock joint

Also called: Snap joint, button lock

Interlocking round pipe joint.

Snap-lock round pipe

Also called: Snap pipe, snap seam pipe, SL pipe

Round pipe with snap-lock longitudinal seam.

Snap-lock seam

Also called: Snap seam, button lock seam

Interlocking seam for round pipe.

Spin-in collar

Also called: Spin-in, self-tapping collar, snap-in collar

Taps into round duct with cutting edge.

Spiral duct

Also called: Spiral pipe, round spiral, lockseam pipe

Round duct with spiral lockseam.

Spiral lockseam

Also called: Spiral seam, lockseam

Continuous spiral seam on round duct.

Spiral pipe connector

Also called: Spiral coupling, slip joint

Connects spiral pipe sections.

Square elbow

Also called: Mitered elbow, square bend

90-degree elbow with mitered corners.

Standing S joint

Also called: Standing S-slip, vertical S joint

Uses standing S-cleat for transverse joint.

Standing S-cleat

Also called: Standing S, S-cleat, standing seam cleat

Vertical S-shaped cleat for transverse joints.

Standing seam

Also called: Longitudinal seam, joint seam

Seam running length of duct.

Supply diffuser

Also called: SD, ceiling diffuser, air diffuser

Diffuser for supply air.

Takeoff collar

Also called: TO collar, branch collar

Collar for branch connection.

TDC

Also called: Transverse Duct Connector

-. Verify the matching shop system, corners, gasket, and approved hardware before assembly.

TDC flange

Also called: Transverse Duct Connector flange, T-DC

Roll-formed flange system for rectangular duct. Verify the matching shop system, corners, gasket, and approved hardware before assembly.

TDF flange

Also called: Transverse Duct Flange, T-DF

Four-bolt flange system, distinct from TDC. Verify the matching shop system, corners, gasket, and approved hardware before assembly.

Tee

Also called: T-branch, tee fitting

90-degree branch fitting.

Tek screw

Also called: Self-drilling screw, drill point screw

Self-drilling fastener with drill point.

Threaded rod

Also called: All-thread, threaded bar, studding

Continuously threaded rod for hangers.

Throw

Also called: Air throw, projection distance

Distance air travels from diffuser.

Transition

Also called: Reducer, taper, adaptor, Eccentric / Concentric

Changes duct size or shape.

Transverse duct connector

Also called: TDC, T-DC connector

Roll-formed flange connection system.

Transverse duct flange

Also called: TDF, T-DF flange

Four-bolt flange system, distinct from TDC.

Transverse joint

Also called: Cross joint, section joint, duct joint

Joint between duct sections.

Trunk line

Also called: Main trunk, main duct, primary duct

Main distribution duct.

Turning vanes

Also called: Vanes, splitters, flow vanes

Curved blades in elbow to reduce turbulence.

UL 181 mastic

Also called: UL mastic, listed mastic

UL-listed duct sealant.

UL 181 tape

Also called: UL tape, listed tape, code tape

UL-listed pressure-sensitive tape.

UL 555

Also called: UL 555 standard, fire damper standard

Standard for fire dampers.

UL 555S

Also called: UL 555S standard, smoke damper standard

Standard for smoke dampers.

Volume control damper

Also called: VCD, balancing damper

Adjusts airflow volume.

Volume damper

Also called: VD, balancing damper, manual damper

Manual airflow adjustment damper.

Water-based duct mastic

Also called: Latex mastic, water mastic, pookie

Common water-based sealant.

Wedge anchor

Also called: Expansion anchor, concrete wedge

Expands in concrete hole.

Wye

Also called: Y-branch, branch wye, lateral

Branching fitting with angled split.

Zip screw

Also called: Self-piercing screw, needle point screw

Pierces thin sheet metal.

Air changes per hour

Also called: ACH, air changes

Room air turnover rate.

Air Drop

Also called: terminal velocity drop

Vertical drop of air stream.

Angle ring connector

Also called: Flange ring, angle ring joint

Angle iron ring for bolting round duct.

Backdraft damper

Also called: Gravity damper one-way damper

Allows flow in one direction only. Prevents reverse airflow.

Band saw

Also called: Portaband, portable band saw

Power saw for straight cuts.

Bead

Also called: Stiffening bead, reinforcement bead

Raised ridge for stiffening sheet metal.

Bead crimp

Also called: Beaded crimp, roll crimp

Crimp with reinforcing bead.

Bell end

Also called: Bell mouth, flared end, socket end

Flared end for pipe joint.

Bend allowance

Also called: BA

Material added for bend radius compensation.

Boot

Also called: Duct boot, register boot, box boot

Transition from duct to register/grille.

Bottom tap

Also called: Bottom outlet, bottom takeoff

Branch outlet from bottom of duct.

Break metal

Also called: Brake metal, brake stock

Sheet metal formed on a brake.

Breakaway connection

Also called: Fusible connection, melt-away

Connection that fails at high temperature.

Burrs

Also called: Sharp edges, slag

Sharp edges left after cutting.

Button punch joint

Also called: Button punch lock, snap lock joint

Mechanically locked joint.

Canvas connector

Also called: Fabric connector, cloth connector, Flex connection

Canvas sleeve for equipment connection.

Ceiling penetration

Also called: Ceiling sleeve, membrane penetration

Duct through rated ceiling.

Ceiling radiation damper

Also called: CRD, radiation damper

Protects ceiling membrane penetrations.

Cheek

Also called: Side cheek, elbow cheek

Side panel of rectangular elbow.

Circumference rule

Also called: Circumference tape, pi tape

Tape measure showing diameter from circumference.

Cleat bender

Also called: Cleat former, S-cleat bender

Forms S-cleats and drive cleats.

Companion angle joint

Also called: Angle flange joint, bolted angle joint

Bolted angle iron flange connection.

Concentric reducer

Also called: Concentric taper, straight reducer

Reducer centered on axis.

Concrete insert

Also called: Channel insert, coil insert

Embedded concrete hanger point.

Concrete screw

Also called: Tapcon, masonry screw, concrete fastener

Screw for concrete attachment.

Conical tap

Also called: Cone tap, tapered tap

Tap with conical transition to round.

Corner piece

Also called: Corner connector, gusset corner

Corner reinforcement for duct.

Corridor damper

Also called: CD, corridor smoke damper

Smoke damper in corridor duct.

Curtain blade damper

Also called: Curtain damper, multiple blade

Blades fold like curtain when closing.

Damper access panel

Also called: Access door, inspection panel

Panel for damper inspection access.

Damper actuator

Also called: Actuator, motor, operator

Device that opens/closes damper.

Damper box

Also called: DB, register box, diffuser box

Box with integral damper for register.

Damper commissioning

Also called: Damper startup, damper verification

Final verification of damper function.

Damper operator

Also called: Operator, motor operator

Device that operates damper.

Damper position switch

Also called: DPS, end switch, limit switch

Indicates damper position.

Damper quadrant

Also called: Quadrant, damper handle, operator

Handle for adjusting volume damper.

Damper sleeve gauge

Also called: Sleeve thickness, sleeve gauge

Thickness of damper sleeve material.

Damper tag

Also called: ID tag, damper label

Identifies damper location and rating.

Deburring

Also called: Grinding edges, cleaning edges

Removing sharp edges from cut metal.

Diffuser boot

Also called: Plenum boot, register boot

Transition from duct to diffuser.

Drop-in anchor

Also called: Drop-in, concrete insert

Threaded insert for concrete.

Duct fabric connector

Also called: Canvas connector, flexible sleeve

Fabric sleeve for equipment connection.

Duct gasket

Also called: Rubber gasket, EPDM gasket

Rubber seal for duct joints.

Duct liner adhesive

Also called: Liner glue, liner cement

Adhesive for attaching duct liner.

Duct reinforcement

Also called: Stiffener, reinforcement, bracing

Added material to prevent duct deformation.

Duct sleeve

Also called: Sleeve, penetration sleeve

Duct through wall/floor penetration.

Ductmate

Flagged: variation.

Dynamic closure

Also called: Dynamic rated, airflow closure

Damper closes against airflow.

E-Z Flange

Flagged: manufacturer-specific.

E-Z Tap

Flagged: manufacturer-specific.

Eccentric reducer

Also called: Eccentric taper, offset reducer

Reducer with offset centerlines.

Elbow template

Also called: Elbow pattern, throat template

Pattern for laying out elbows.

Electric actuator

Also called: Electric motor, spring return actuator

Electrically powered damper operator.

End cap

Also called: Cap, blind end, closure

Closes end of duct run.

End switch

Also called: Limit switch, position switch

Indicates damper fully open/closed.

Exhaust grille

Also called: Exhaust register, relief grille

Grille for exhaust air.

Face size

Also called: Face dimension, overall size

Visible face dimension of diffuser.

Fire-rated sleeve

Also called: Fire sleeve, penetration sleeve

Sleeve with fire rating.

Firestat

Also called: Fire thermostat, high-limit stat

Temperature-activated fire safety device.

Firestop pillow

Also called: Pillow, fire pillow

Compressible firestop material.

Firestop putty

Also called: Putty pad, fire putty

Moldable firestop material.

Flange sealant

Also called: Flange caulk, flange mastic

Sealant for flange faces.

Flange washer

Also called: Flat washer

Washers for flange connections.

Flexible connector

Also called: Vibration isolator, flex joint

Flexible connection for vibration.

Flexible duct connector

Also called: Flex connector, canvas connector

Flexible connection for vibration isolation.

G90

Galvanized coating.

Gasketed joint

Also called: Rubber gasket joint, sealed joint

Joint with rubber gasket seal.

Gore

Also called: Gore section, pie section

Wedge-shaped section for forming round fittings.

Gored elbow

Also called: Segmented elbow, pie elbow

Elbow made from gore sections.

Header

Also called: Manifold, distribution header

Main distribution chamber.

Heat detector

Also called: Thermal detector, fire detector

Detects excessive heat.

Heel

Also called: Heel radius, heel section

Outer curved section of elbow or transition.

Hem

Also called: Hemmed edge, safety edge

Folded edge for safety and stiffness.

HETO

Also called: High-Efficiency Takeoff

Flagged: manufacturer-specific.

Joint reinforcement

Also called: Joint stiffener, joint brace

Added material to strengthen joint.

Lag screw

Also called: Lag bolt, wood screw

Screw for wood attachment.

Lap joint

Also called: Lapped joint, overlap joint

Overlapping pipe connection.

Leak lock

Also called: Thread sealant, pipe dope

Seals threaded connections.

Leakage test

Also called: Duct test, pressure test, smoke test

Testing duct for air leaks.

Linear diffuser

Also called: Slot diffuser, bar diffuser, linear grille

Long narrow diffuser.

Liner cap

Also called: Pin cap, insulation cap

Cap welded over liner pin.

Liner pin

Also called: Insulation pin, weld pin

Pin for securing duct liner.

Longitudinal seam pipe

Also called: L-seam pipe, straight-seam pipe

Round pipe with straight longitudinal seam.

Louvered face diffuser

Also called: Louvered diffuser, adjustable diffuser

Diffuser with adjustable louvers.

Machine screw

Also called: Machine bolt, threaded screw

Screw for threaded holes.

Motorized control damper

Also called: MCD, automatic damper

Electrically controlled damper.

Motorized damper

Also called: Actuated damper, power damper

Damper with electric/pneumatic actuator.

Motorized fire damper

Also called: MFD, motorized FD

Fire damper with motorized closure.

Multi-blade damper

Also called: Parallel blade, opposed blade

Multiple blades in parallel or opposed arrangement.

Neck adaptor

Also called: Reducer collar, adaptor collar, Reducer neck, transition neck

Connects different sizes/types. Connects duct to diffuser neck.

Offset

Also called: Z-offset, jog, dogleg

Fitting to avoid obstruction.

Oval duct

Also called: Flat oval, oval pipe, obround duct

Flattened round duct for low clearance.

Oval major axis

Also called: Major dimension, long side

Long dimension of oval duct.

Oval minor axis

Also called: Minor dimension, short side

Short dimension of oval duct.

Ovalizer

Also called: Oval forming machine, flat oval machine

Forms round pipe into oval shape.

Pin welder

Also called: Cap welder, liner pin welder

Welds pins for securing insulation/liner.

Pipe clamp

Also called: Duct clamp, hose clamp, worm drive clamp

Clamps round duct connections.

Pipe cutter

Also called: Tube cutter, wheel cutter

Cuts round pipe cleanly.

Pipe insulation sleeve

Also called: Insulation jacket, pipe wrap

Pre-formed insulation for round pipe.

Pipe liner

Also called: Internal liner, acoustical liner

Internal insulation lining.

Pipe wrap

Also called: Duct wrap, fiberglass wrap

Wrap-around insulation for pipe.

Pop rivet

Also called: Blind rivet, rivet

Fastener for metal connections.

Post-installed anchor

Also called: Expansion bolt, wedge bolt

Anchor installed after concrete pour.

Pressed elbow

Also called: Stamped elbow, die-formed elbow

Factory-formed round elbow.

Pressure-sensitive tape

Also called: PS tape, adhesive tape

Tape with pressure-activated adhesive.

Prick punch

Also called: Center punch, layout punch

Makes small indentation for drill starting.

Radius elbow

Also called: Swept elbow, smooth elbow

Elbow with curved throat and heel.

Raw edge

Also called: Cut edge, sheared edge

Unfinished edge of cut sheet metal.

Return diffuser

Also called: RD, return air diffuser

Diffuser for return air.

Riser

Also called: Vertical duct, shaft duct

Vertical duct running between floors.

Riser clamp

Also called: Pipe riser clamp, floor clamp

Supports vertical round duct.

Rod coupling

Also called: Coupling nut, rod connector

Connects threaded rod sections.

Rotary lock former

Also called: Lock forming machine, Pittsburgh machine

Forms Pittsburgh locks on sheet edges.

Round backdraft damper

Also called: Gravity damper, round relief damper

One-way damper for round duct.

Round cap

Also called: End cap, pipe cap, bull cap

Closes end of round duct.

Round coupling

Also called: Sleeve coupling, pipe coupling

Connects two round duct sections.

Round saddle

Also called: Pipe saddle, welded saddle

Branch saddle on round duct.

Round tee

Also called: Bullhead tee, branch tee

T-branch for round duct.

Round transition

Also called: Taper, reducer, cone

Size change for round duct.

Round wye

Also called: Y-branch, lateral, wye fitting

Angled branch for round duct.

Scriber

Also called: Scratch awl, layout scriber

Sharp tool for marking metal.

Seam closer

Also called: Lock former, seam locker

Machine for closing Pittsburgh locks.

Sheet-Metal Drop

Also called: Scrap, remnant, leftover

Leftover material from sheet.

Shoe tap

Also called: Shoe fitting, boot tap

Tap with angled entry like a shoe.

Side tap

Also called: Side outlet, side takeoff

Branch outlet from side of duct.

Silicone sealant

Also called: RTV silicone, caulking

Flexible sealant for joints.

Single blade damper

Also called: Butterfly damper, round blade damper, one-blade damper

Single round blade in rectangular frame. Single round or rectangular blade.

Sleeve anchor

Also called: Sleeve bolt, expansion sleeve

Sleeve expands when bolt tightened.

Sleeve length

Also called: Damper sleeve length

Required length of damper sleeve.

Slip connection

Also called: Slip joint, slip fit

Sliding fit connection.

Smoke damper sleeve

Also called: SD sleeve, damper sleeve

Sleeve housing smoke damper.

Solvent-based mastic

Also called: Oil-based mastic, solvent mastic

Stronger but more hazardous sealant.

Spigot end

Also called: Plain end, male end

Plain end that fits into bell/socket.

Spiral pipe machine

Also called: Spiral former, pipe mill

Forms spiral lockseam pipe from coil.

Split ring hanger

Also called: Ring hanger, pipe ring

Ring that wraps around pipe.

Spread

Also called: Air spread, coverage pattern

Lateral spread of air from diffuser.

Spring return actuator

Also called: SR actuator, fail-safe actuator

Returns to default position on power loss.

Stairwell pressurization damper

Also called: Pressurization damper, stair damper

Maintains stairwell pressure.

Standing seam connection

Also called: Standing seam joint

Uses standing seam for joint.

Start collar

Also called: Starter, neck collar

Collar for connecting to equipment.

Static closure

Also called: Static rated, no-flow closure

Damper closes with no airflow.

Surface mount diffuser

Also called: Surface diffuser, flush mount

Mounts on surface of ceiling/wall.

T-bar diffuser

Also called: T-bar grille, lay-in diffuser

Diffuser for T-bar ceiling grid.

Tab collar

Also called: Tabbed collar, crimp-on collar

Collar with tabs for securing to duct.

Teflon tape

Also called: PTFE tape, plumber's tape, thread tape

Seals threaded pipe joints.

Terminal velocity

Also called: TV, throw velocity

Velocity at end of throw.

Test port

Also called: Test hole, probe port, pitot tube port

Small port for airflow measurement.

Throat

Also called: Throat radius, throat section

Inner curved section of elbow or transition.

Toggle bolt

Also called: Toggle anchor, wing bolt

Anchor for hollow walls.

Top tap

Also called: Top outlet, top takeoff

Branch outlet from top of duct.

Two-position actuator

Also called: On/off actuator, open/close actuator

Only fully open or fully closed.

Vane rail

Also called: Vane track, vane runner

Track that holds turning vanes.

Vapor barrier tape

Also called: Foil tape, vapor seal tape

Seals insulation vapor barrier.

Welded connection

Also called: Weld, field weld, shop weld

Permanent welded joint.

Acoustic sealant

Also called: Sound sealant, non-hardening caulk

Remains flexible for sound sealing.

Adjustable swivel ring

Also called: Swivel ring, swivel hanger

Ring with swivel for angled pipe.

Anti-smudge ring

Also called: Dirt ring, smudge ring

Ring to prevent ceiling.

Automatic balancing damper

Also called: ABD, constant volume damper

Self-adjusts to maintain set airflow.

Auxiliary switch

Also called: Aux switch, extra switch

Additional position indication switch.

Barometric damper

Also called: Bypass damper, relief damper

Opens at set pressure to relieve excess.

Barometric relief damper

Also called: Barometric damper, pressure relief

Opens at set static pressure.

Blade linkage

Also called: Linkage arm, connecting rod

Connects blades to actuator.

Blade seal

Also called: Jamb seal, edge seal

Seal on damper blade edges.

Brazed joint

Also called: Braze, silver solder

High-temperature solder joint.

Butyl sealant

Also called: Butyl tape, butyl caulk

Rubber-based sealant.

Closed-cell gasket

Also called: Neoprene gasket, sponge gasket

Compressible gasket material.

Closed-end rivet

Also called: Sealed rivet, waterproof rivet

Sealed mandrel end.

Control wiring

Also called: Low voltage wiring, damper wiring

Wiring for electric damper controls.

Converging section

Also called: Reducer section, taper

Narrowing transition section.

Cookie

Also called: Duct cutout scrap, waste piece

Scrap piece from cutting duct openings.

Core diffuser

Also called: Removable core, adjustable core

Diffuser with removable center section.

Core removal

Also called: Core out, removable core

Diffuser core can be removed.

Core velocity

Also called: Neck velocity, inlet velocity

Velocity at diffuser inlet.

Cornermatic

Also called: Corner machine, corner former

Automated corner forming machine.

Cross

Also called: Crossover, four-way

Four-way intersection fitting.

Cross break

Also called: Cross-brake, stiffening bend

X-shaped bends for panel stiffening.

Cross break joint

Also called: Stiffening joint, reinforcement joint

Joint with cross-break stiffening.

Damper blade seal

Also called: Blade gasket, jamb seal

Seal on damper blade edges.

Damper frame seal

Also called: Frame gasket, perimeter seal

Seal around damper frame.

Damper heater

Also called: Heater coil, freeze protection

Prevents damper freezing.

Damper jack

Also called: Damper prop, hold-open

Temporary hold-open during installation.

Damper jackshaft

Also called: Jackshaft, connecting shaft

Shaft connecting multiple damper sections.

Damper linkage

Also called: Linkage, damper rod

Connects actuator to damper blades.

Diverging section

Also called: Diffuser section, spreader

Widening transition section.

Double-wall vane

Also called: Airfoil vane, streamlined vane

Vane with airfoil cross-section.

Eggcrate grille

Also called: Eggcrate, cellular grille

Grille with eggcrate pattern.

Face velocity

Also called: FV, outlet velocity

Velocity at diffuser face.

Floor support

Also called: Floor stand, pipe stand

Freestanding support for pipe.

Flow straightener

Also called: Straightening vanes, flow grid

Reduces turbulence for measurement.

Frame seal

Also called: Perimeter seal, damper gasket

Seal around damper frame.

Grain direction

Also called: Roll direction, grain

Direction of metal grain from rolling process.

Gravity vent damper

Also called: Gravity damper, vent damper

Opens by gravity, closes by spring.

Hinged access door

Also called: Hinged panel, swing door

Access door with hinges.

Jackshaft

Also called: Connecting shaft, blade shaft

Shaft connecting multiple damper sections.

Joint clamp

Also called: Duct clamp, seam clamp

Clamps joint during sealing.

K-factor

Also called: Neutral axis factor

Ratio for calculating bend allowance.

Large flange rivet

Also called: LF rivet, oversize rivet

Rivet with large head.

Latex caulk

Also called: Acrylic caulk, painter's caulk

Water-based caulk.

Layout dye

Also called: Layout fluid, bluing, dyekem

Blue fluid for marking layout lines.

Mitered Elbow

Sharp rectangular elbow without a smooth radius; turning vanes or another approved airflow treatment may be required by the design or specification.

Modulating actuator

Also called: Modulating motor, proportional actuator

Positions damper at variable openings.

Multi-grip rivet

Also called: MG rivet, range rivet

Works in range of thicknesses.

Neoprene connector

Also called: Rubber connector, neoprene sleeve

Rubber flexible connection.

Nesting

Also called: Sheet nesting, layout optimization

Arranging parts on sheet for minimal waste.

Noise criteria

Also called: NC, sound rating, acoustic rating

Sound level rating of diffuser.

Open-cell gasket

Also called: Foam gasket, sponge rubber

Soft gasket material.

Opposed blade damper

Also called: OBD, opposed damper

Blades rotate in opposite directions. Blades rotate opposite directions.

Opposed blade damper box

Also called: OBD box, register box with OBD

Register box with opposed blade damper.

Parallel blade damper

Also called: PBD, parallel damper

Blades rotate same direction.

Perforated diffuser

Also called: Perf diffuser, perforated face

Diffuser with perforated face.

Perforated face

Also called: Perf face, perforated grille

Face with holes for airflow.

Pipe notcher

Also called: Tube notcher, hole notcher

Notches round pipe for saddle fit.

Pipe saddle support

Also called: Saddle support, pipe cradle

Cradle support for round pipe.

Pipe shoe

Also called: Pipe guide, slide support

Supports pipe while allowing movement.

Pipe stretcher

Also called: Pipe expander, swaging tool

Expands pipe end for fitting.

Plenum slot diffuser

Also called: Slot diffuser, T-bar diffuser

Diffuser for T-bar ceiling plenum.

Pneumatic actuator

Also called: Air actuator, pneumatic operator

Air-powered damper operator.

Pneumatic tubing

Also called: Air line, control tubing

Tubing for pneumatic controls.

Polyurethane sealant

Also called: PU sealant, urethane caulk

Durable flexible sealant.

Raw edge joint

Also called: Raw flange joint, slip joint

Simple overlapping joint.

Reinforcing tape

Also called: Mesh tape, fiberglass tape

Tape with embedded mesh for strength.

Resettable fusible link

Also called: Reset link, replaceable link

Fusible link that can be replaced.

Round access cap

Also called: Cleanout cap, inspection cap

Removable cap for round duct access.

Round access door

Also called: Round cleanout, inspection port

Access opening in round duct.

Seam weld

Also called: Continuous weld, longitudinal weld

Continuous weld along seam.

Shaft bushing

Also called: Bushing, bearing, damper bearing

Bearing for damper blade shaft.

Single blade damper box

Also called: Butterfly box, BD box

Register box with single blade damper.

Single-wall vane

Also called: Single vane, one-piece vane

Simple curved turning vane.

Smoke detector sampling tube

Also called: Sampling tube, detector tube

Tube extending into duct for sampling.

Soldered joint

Also called: Solder, sweat joint

Joined with solder (rare in HVAC).

Splitter damper

Also called: Diversion damper, bypass damper

Diverts airflow between branches.

Spot weld

Also called: Resistance weld, stitch weld

Localized weld points.

Spot welder

Also called: Resistance welder, stitch welder

Welds overlapping sheet metal sections.

Stack head

Also called: Stack fitting, riser head

Fitting at top of vertical riser.

Step-down diffuser

Also called: Step diffuser, drop diffuser

Diffuser with stepped face.

Trammel points

Also called: Beam compass, large compass

For drawing large arcs and circles.

Transfer grille

Also called: Transfer register, pass-through grille

Grille in partition for air transfer.

Vane spacer

Also called: Vane clip, vane holder

Maintains spacing between vanes.

Vanstone flange

Also called: Lapped flange, loose flange

Flange that laps over pipe end.

Wire edge

Also called: Rolled edge, wired edge

Edge rolled around wire for reinforcement.

Wrap pattern

Also called: Wraparound template

Pattern wrapped around round duct.