FD | TROX HESCO Schweiz AG

Circular diffuser face with circular plenum box and horizontal spigot

Square diffuser face with square plenum box and horizontal spigot

Circular diffuser face with circular plenum box and vertical spigot

Horizontal swirling air discharge

For comfort zones, with fixed air control blades

Circular and square swirl diffusers with high induction for high air change rates
■ Nominal sizes 300, 400, 500, 600, 625
■ Volume flow 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 constant and variable volume flows
■ For all ceiling systems, and with an extended border also suitable for freely suspended installation
■ Small swirl diffusers for 600 and 625 ceiling grids
■ High induction results in a rapid reduction of the temperature difference and air velocity
■ Ideal for comfort zones

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

General information

Application

Swirl diffusers for supply air and extract air in comfort zones
A design feature for building owners and architects with high demands on architecture and design
Horizontal swirling supply air discharge for mixing ventilation
Efficient swirling airflow with high induction for rapid reduction of temperature differences and air velocity (supply air)
For constant and variable volume flows
For supply air to room air temperature differences of -12 – +10 K
For rooms with heights up to 4 m (underside of suspended ceiling)
For all types of ceiling systems

Smaller swirl diffusers suitable for 600 or 625 ceiling grids

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 ceiling systems, and with an extended border also suitable for freely suspended installation
Smaller swirl diffusers suitable for 600 or 625 ceiling grids
Spigot horizontal and vertical
Very high room air change rates possible thanks to row arrangement with a minimum centre-to-centre spacing 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

Spigot

H: horizontal spigot
V: vertical spigot

Accessories

Lip seal

Optionally available

Note: For circular plenum box with horizontal spigot: Lip seal only available in combination with damper blade

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 air ducts according to DIN EN 1506 or DIN EN 13180
Spigots are always fitted with a groove for a lip seal
Retrofitting of the lip seal is possible at a later stage
Optional: Lip seal and damper blade are factory-fitted
Simple installation of the diffuser face using a central fixing screw with cap

Square plenum box

Spigot made of galvanised sheet steel
Equalising element to ensure a uniform airflow through the diffuser face (supply air variant)

Circular plenum box

With vertical spigot: Spigot made of galvanised sheet steel
With horizontal spigot: Spigot made of black ABS plastic
Equalising element to ensure a uniform airflow through the diffuser face (supply air variant)

Materials and surfaces

Diffuser face

Made of galvanised sheet steel
Powder-coated, RAL 9010, pure white (no entry)
P1: powder-coated, RAL CLASSIC colour

Damper blade

Made of ABS plastic

Circular plenum box

Made of galvanised sheet steel
With vertical spigot

Spigot made of galvanised sheet steel
For supply air, with galvanised perforated plate for air distribution

With horizontal spigot

Spigot made of black ABS plastic, flame-retardant in accordance with UL94, V0
Equipped with a polyester equalising element for supply air

Crossbar made of galvanised sheet steel for mounting the diffuser face

Square plenum box

Made of galvanised sheet steel
With horizontal spigot
Spigot made of galvanised sheet steel
For supply air, with galvanised perforated plate for air distribution
Crossbar made of galvanised sheet steel for mounting the diffuser face

Lip seal

Made of Evoprene

Standards and guidelines

Spigot, suitable for air ducts according to DIN EN 1506 or DIN EN 13180
Sound power level of the air-regenerated noise measured according to DIN EN ISO 5135

Maintenance

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

Disclosure of Chemicals

RoHS EU Directive 2011/65/EU (RoHS)

This product or single variants comply with EU Directive 2011/65/EU (RoHS) on the restriction of the use of certain hazardous substances in electrical and electronic equipment. For more information, please refer to our Environmental Product Declarations.

REACH 1907/2006 (EC Regulation REACH)

This product or single variants comply with the provisions of EC Regulation No. 1907/2006, also known as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). For more information, please refer to our Environmental Product Declarations.

Technical information

Schematic illustration: 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 balancing

9 Pressure tap

10 Green cord, closing the damper blade

11 White cord, 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)

Swirl diffusers discharge supply air from HVAC systems into the room with a swirling airflow pattern. The resulting airflow induces high levels of indoor air, thereby rapidly reducing the airflow velocity and the temperature difference between supply air and room air. Large volume flows are possible with swirl diffusers. This results in mixing ventilation for comfort areas, ensuring effective room air circulation with low turbulence in the occupied zone. Type FD swirl diffusers have fixed air control blades. Airflow pattern is horizontal with radial distribution. The supply air to room air temperature difference can be -12 – +10 K. A damper blade (optional) simplifies volume flow balancing at commissioning. Pressure tap and cord-operated damper blade (optional) allow for volume flow balancing with the diffuser face in place. To achieve a uniform architectural design, type FD diffusers may also be used for extract air.

Nominal sizes	300, 400, 500, 600, 625 mm
Dimensions ceiling panel	598 x 598 or 623 x 623
Minimum volume flow rate, with Δtz = -6 K	9 – 28 l/s or 31 – 102 m³/h
maximum volume flow, at LWA ≅ 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

Swirl diffusers FD with a square or circular diffuser face.

For supply air and extract air in comfort zones
Up to 35 air changes per hour
For installation into all types of suspended ceilings

Ready-to-install component, consisting of:

Diffuser face with radially arranged blades
Square or circular plenum box

Plenum box

With square diffuser face (-Q) and horizontal spigot (-H): square design

With drill holes for suspension

With circular diffuser face (-R) and horizontal spigot (-H): circular design

Suspension lugs for hanging

For square (-Q) or circular (-R) diffuser face with vertical spigot (-V): circular design

With suspension lugs for hanging

Spigot with groove for factory-fitted or retrofitting with lip seal
Spigot with mounting points for a damper blade

The damper blade can be retrofitted to galvanised spigots

For supply air, equipped with an equalising element
With crossbar for mounting the diffuser face

Diffuser face

Diffuser face with fixed air control blades for horizontal swirling air distribution with high induction
The diffuser face is fixed to the crossbar with a central screw, concealed by a decorative cap

Special characteristics

High induction results in a rapid reduction of the supply air to room air temperature difference and airflow velocity
For all ceiling systems, and with an extended border also suitable for freely suspended installation
Smaller swirl diffusers suitable for 600 or 625 ceiling grids
Spigot horizontal and vertical
Very high room air change rates possible thanks to row arrangement with a minimum centre-to-centre spacing of 0.9 m

Materials and surfaces

Diffuser face

Made of galvanised sheet steel
Powder-coated, RAL 9010, pure white (no entry)
P1: powder-coated, RAL CLASSIC colour

Damper blade

Made of ABS plastic

Circular plenum box

Made of galvanised sheet steel
With vertical spigot

Spigot made of galvanised sheet steel
For supply air, with galvanised perforated plate for air distribution

With horizontal spigot

Spigot made of black ABS plastic, flame-retardant in accordance with UL94, V0
Equipped with a polyester equalising element for supply air

Crossbar made of galvanised sheet steel for mounting the diffuser face

Square plenum box

Made of galvanised sheet steel
With horizontal spigot
Spigot made of galvanised sheet steel
For supply air, with galvanised perforated plate for air distribution
Crossbar made of galvanised sheet steel for mounting the diffuser face

Lip seal

Made of Evoprene

Technical data

Nominal sizes: 300, 400, 500, 600, 625 mm

Minimum volume flow rate, at ΔtZ = -6 K: 9 – 28 l/s or 31 – 102 m³/h

Maximum volume flow, at LWA ≅ 50 dB(A): 70 – 235 l/s or 252 – 846 m³/h

Supply air to room air temperature difference: -12 – +10 K

Standards and guidelines

Spigot, suitable for air ducts according to DIN EN 1506 or DIN EN 13180
Sound power level of the air-regenerated noise measured according to DIN EN ISO 5135

–

500 x 598

P1 - RAL 9016

1 Type
FD Swirl diffuser

2 Construction style
R circular
Q square

3 System
Z Supply air
A Extract air

4 Spigot
H with horizontal spigot
V with vertical spigot (the plenum box is always circular)

5 Damper blade for volume flow balancing
No entry: without damper blade
M with damper blade
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]
Nominal size swirl diffuser x ceiling tile size

Nominal size swirl diffuser
300, 400, 500, 600, 625

Ceiling tile size (only with construction style Q)
No entry: Ceiling tile size according to nominal size swirl diffuser
598 square ceiling tile, 598 x 598 mm (not for nominal size 625 swirl diffuser)
623 square ceiling tile, 623 x 623 mm

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. Features 2 and 4 define the plenum box geometry.

Order example: FD-Q-Z-H-M-L/500×598/P1-RAL9016

Type	FD – Swirl diffuser
Construction style	square
System	Supply air
Spigot	with horizontal spigot
Damper blade for volume flow balancing	with damper blade
Accessories	with lip seal
Nominal size [mm]	Nominal size 500, square ceiling panel, 598 x 598 mm
Exposed surface	powder-coated, RAL 9016 (traffic white), GU 70

Downloads

informazioni di prodotto

Product data sheet FD

FD_PD_2026_06_09_DE_en Product data sheet 870 KB pdf

brochure

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

certificati

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

manuali d'uso

Installation manual Ceiling diffusers

A00000054447 Installation manual 520 KB pdf

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FD

For comfort zones, with fixed air control blades

General information

Technical information

Downloads

informazioni di prodotto

Product data sheet FD

brochure

Deckenluftdurchlaesse_IM_A00000054447_V2_2018_06_GB_enpdf.pdf

E013CD1_Beipackzettel_Deckenluftdurchlaesse_Ceiling_diffuser_DE_de_enpdf.pdf

Deckenluftdurchlaesse_IM_A00000054447_V2_2018_06_GB_enpdf.pdf

certificati

FD_HC_2020_06_08_DE_enpdf.pdf

Declaration of hygiene conformity Ceiling Swirl Diffusers Types FD, RFD, FDE

Declaration of hygiene conformity Type FD

Non-CE Manufacturer's statement FD

manuali d'uso

Installation manual Ceiling diffusers

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