FD | TROX AUSTRIA + CEE GmbH

Circular diffuser faces with circular plenum box

Square diffuser face with square plenum box

Circular diffuser face with circular plenum box and top entry spigot

Horizontal swirling air discharge

FD

For comfort zones, with fixed air control blades

Circular and square ceiling swirl diffusers that create high induction levels, for high room air change rates
■ Nominal sizes 300, 400, 500, 600, 625
■ Volume flow rate range 9 – 235 l/s or 31 – 846 m³/h
■ Diffuser face made of galvanised sheet steel, powder-coated
■ For supply and extract air
■ For variable and constant volume flows
■ For all types of ceiling systems, and with an extended border also suitable for freely suspended installation
■ High induction results in a rapid reduction of the temperature difference and airflow velocity
■ Very high room air change rate possible thanks to row arrangement with a minimum pitch distance of 0.9 m
■ Ideal for comfort zones
■ Circular diffuser faces can be easily mounted without tools in a circular plenum box with horizontal spigot

Optional equipment and accessories
■ Exposed diffuser face available in RAL CLASSIC colours
■ Square plenum box with cord-operated damper unit and pressure tap

Initialize order code

General information

Application

Ceiling swirl diffusers are used as supply air or extract air diffusers for comfort zones
Attractive design element for building owners and architects with demanding aesthetic requirements
Horizontal swirling supply air discharge for mixed flow ventilation
The efficient swirl creates high induction levels, thereby rapidly reducing the temperature difference and airflow velocity (supply air variant)
For variable and constant volume flows
For supply air to room air temperature differences from -12 – +10 K
For room heights up to 4 m (lower edge of suspended ceiling)
For all types of ceiling systems
With an extended border also suitable for freely suspended installation (supply air variant)

Special characteristics

High induction results in a rapid reduction of the supply air to room air temperature difference and airflow velocity
For all types of ceiling systems, and with an extended border also suitable for freely suspended installation
Horizontal or vertical duct connection
Very high room air change rate possible thanks to row arrangement with a minimum pitch distance of 0.9 m

Nominal sizes

300, 400, 500, 600, 625

Variants

FD-Q: square diffuser face
FD-R: circular diffuser face
FD-*-Z: Supply air
FD-*-A: Extract air

Connection

H: horizontal duct connection
V: vertical duct connection

Accessories

Lip seal

For circular plenum boxes with horizontal connection spigot, the lip seal is only available in combination with the flow adjustment damper. Otherwise, it can always be selected optionally.

Attachments

M: Damper element for volume flow rate balancing
MN: Pressure tap and cord-operated damper unit for volume flow rate balancing with the diffuser face in place (only possible with square plenum box)

Construction features

Spigot suitable for circular ducts to EN 1506 or EN 13180

Square plenum boxes and plenum boxes with vertical connection

With spigot made of galvanised sheet steel
Groove only available if lip density characteristic has been selected

Circular plenum boxes with horizontal spigot for nominal sizes 250, 400L, 400H and 600

Spigot made of black ABS
Spigots are fitted with a groove for a lip seal
Retrofitting of the lip seal is possible at a later stage
Damper blade and lip seal (optional) are factory fitted
Plenum box for supply air, with an optimised equalising element that ensures a uniform airflow through the diffuser face
Simple installation of the diffuser face due to central fixing screw with cap
Plenum box for supply air, with an optimised equalising element that ensures a uniform airflow through the diffuser face
Simple installation of the diffuser face due to central fixing screw with decorative cap

Materials and surfaces

Grille face made of galvanised sheet steel
Q; R: Plenum box made of galvanised sheet steel including galvanised sheet steel cross bar to support the diffuser face
Plenum boxes with vertical connection and square plenum boxes with horizontal connection: for supply air always with galvanised perforated plate for air distribution
Circular plenum boxes with horizontal spigot: Equipped as a plenum box for supply air with an equalising element made of polyester
Square plenum boxes and plenum boxes with vertical spigot: Spigot made of galvanised sheet steel
Circular plenum boxes with horizontal spigot: Spigot made of black ABS, according to UL94, V0 flame retardant
Lip seal made of Evoprene
Diffuser face powder-coated, RAL 9010, pure white
P1: Powder-coated, RAL Classic colour

Standards and guidelines

Sound power level of the air-regenerated noise measured according to EN ISO 5135

Maintenance

Low maintenance as construction and materials are not subject to wear
Inspection and cleaning to VDI 6022

Technical information

Schematic illustration of FD with square plenum box and side entry spigot

① Diffuser face

② Central fixing screw with decorative cap

③ Plenum box

④ Cross bar

⑤ Suspension hole

⑥ Spigot

Optional

⑦ Lip seal

⑧ Damper blade for volume flow rate balancing

⑨ Pressure tap

⑩ Green cord for closing the damper blade

⑪ White cord for opening the damper blade

⑫ Measuring tube

⑬ Text label indicating plenum box variant

⑭ Perforated plate as an equalising element (only for supply air)

Ceiling swirl diffusers in air conditioning systems create a swirl to supply air to rooms. The resulting airflow induces high levels of room air, thereby rapidly reducing the airflow velocity and the temperature difference between supply air and room air. Ceiling swirl diffusers allow for large volume flow rates. The result is a mixed flow ventilation in comfort zones, with good overall room ventilation, creating only very little turbulence in the occupied zone. Type FD ceiling swirl diffusers have fixed blades. Air discharge is horizontal omni directional. The supply air to room air temperature difference may range from –12 to +10 K. A damper blade (optional) simplifies volume flow rate balancing for commissioning. Pressure tap and cord-operated damper blade (optional) allow for volume flow rate balancing with the diffuser face in place. To give rooms an aesthetic, uniform look, Type FD diffusers may also be used for extract air.

Nominal sizes	300, 400, 500, 600, 625 mm
Minimum volume flow rate, with Δt_z = -6 K	9 – 28 l/s or 31 – 102 m³/h
Maximum volume flow rate, with L_WA ≅ 50 dB(A)	70 – 235 l/s or 252 – 846 m³/h
Supply air to room air temperature difference	-12 – 10 K

This specification text describes the general properties of the product. Texts for variants can be generated with our Easy Product Finder design program.

Specification text

Ceiling swirl diffusers with square or circular diffuser face.

Supply air and extract air variants for comfort zones, for a maximum air change rate of 35 per hour. Diffuser face with individually manually adjustable air control blades for horizontal swirling supply air discharge creating high induction levels. For installation into all types of suspended ceilings.

Ready-to-install component consisting of the diffuser face with radially arranged, individually adjustable black or white set of air control blades and a plenum box, which is also square in the case of square faceplates (-Q) and round in the case of rounded faceplates (-R). The plenum box has an equalising element for supply air. The plenum box always includes a horizontally or vertically arranged spigot, cross bar and drilled holes or suspension lugs for suspension.

The diffuser face is fixed to the cross bar with a central screw, concealed by a decorative cap.

Spigot suitable for ducts to EN 1506 or EN 13180.

Sound power level of the air-regenerated noise measured according to EN ISO 5135.

Special characteristics

High induction results in a rapid reduction of the supply air to room air temperature difference and airflow velocity
For all types of ceiling systems, and with an extended border also suitable for freely suspended installation
Horizontal or vertical duct connection
Very high room air change rate possible thanks to row arrangement with a minimum pitch distance of 0.9 m

Materials and surfaces

Grille face made of galvanised sheet steel
Q; R: Plenum box made of galvanised sheet steel including galvanised sheet steel cross bar to support the diffuser face
Plenum boxes with vertical connection and square plenum boxes with horizontal connection: for supply air always with galvanised perforated plate for air distribution
Circular plenum boxes with horizontal spigot: Equipped as a plenum box for supply air with an equalising element made of polyester
Square plenum boxes and plenum boxes with vertical spigot: Spigot made of galvanised sheet steel
Circular plenum boxes with horizontal spigot: Spigot made of black ABS, according to UL94, V0 flame retardant
Lip seal made of Evoprene
Diffuser face powder-coated, RAL 9010, pure white
P1: Powder-coated, RAL Classic colour

Technical data

Nominal sizes: 300, 400, 500, 600, 625 mm
Minimum volume flow rate, for ΔtZ = -6 K: 9 - 28 l/s or 31 - 102 m³/h
Maximum volume flow rate, at LWA ≅ 50 dB(A): 70 – 235 l/s or 252 – 846 m³/h
Supply air to room air temperature difference: -12 to +10 K

–

500

P1 - RAL 9016

1 Type

FD Swirl diffuser

2 Construction style

R circular

Q square

3 System

Z Supply air

A Extract air

4 Connection

H horizontal

V Vertical (circular plenum box)

5 Damper screen for volume flow rate balancing

No entry: without damper screen

M with damper screen

MN with cords and pressure tap (only with square plenum box)

6 Accessories

No entry: without accessories

L with lip seal

7 Nominal size [mm]

300, 400, 500, 600, 625

8 Exposed surface

No entry: powder-coated, RAL 9010 (pure white)

P1 powder-coated, specify RAL CLASSIC colour

Gloss level

RAL 9010 GU 50

RAL 9006 GU 30

All other RAL colours GU 70

Note: Circular plenum boxes with a horizontal spigot have either no damper blade and no lip seal or both a damper blade and a lip seal. Items 2 and 4 define apply to the plenum box.

Order example: FD–Q–Z–H–MN/500/P1–RAL 9016

Construction style	Square
System	Supply air
Connection	Horizontal
Damper blade for volume flow rate balancing	With cord and pressure tap
Accessories	without accessories
Nominal size	500
Exposed surface	RAL 9016, traffic white, GU70

Downloads

brochures

Deckenluftdurchlaesse_IM_A00000054447_V2_2018_06_GB_enpdf.pdf

530 KB pdf
E013CD1_Beipackzettel_Deckenluftdurchlaesse_Ceiling_diffuser_DE_de_enpdf.pdf

29 KB pdf
Deckenluftdurchlaesse_IM_A00000054447_V2_2018_06_GB_enpdf.pdf

530 KB pdf

certificates

FD_HC_2020_06_08_DE_enpdf.pdf

1,6 MB pdf
Declaration of hygiene conformity Ceiling Swirl Diffusers Types FD, RFD, FDE

HC/FD/RFD/FDE/DE/en Declaration of hygiene conformity 140 KB pdf
Declaration of hygiene conformity Type FD

FD_HC_2025_11_en Declaration of hygiene conformity 1,1 MB pdf
Non-CE Manufacturer's statement FD

FD_MS_CE_2026_01_DE_en Non-CE Manufacturer's statement 1000 KB pdf

operation manuals

Installation manual Ceiling diffusers

A00000054447 Installation manual 520 KB pdf

miscellaneous

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