High volume flow, fixed aperture, fixed blade ceiling swirl diffuser, optimised for low-temperature VAV systems.

Key swirl vanes features preserve horizontal discharge during extended VAV turndown:

• Cambered leading edges: aerofoil airflow attachment (vanes do not stall)
• Helical-twist curvature: shallow discharge angle at vane tips
• Bell-mouth exit: strong Coanda-effect attachment to diffuser face

May be mounted flush with ceiling or free-hanging.

	Location – above: Discharge height: 2.4 – 4.5 m Flush with a closed ceiling or freely suspended
	Mixed flow discharge:  Airflow: 10 – 440 L/s (36 – 1584 m³/h) Nominal diameter: DN250; DN355; DN500
	Return air: suitable for use as a return air inlet.
	Low temperature supply: may be used for low temperature (cold air) supply systems (Tsupply ≥ 8°C), where ∆Tsupply-room ≥ -16 K.
	VAV dependent throw: suitable for low-temperature VAV systems. Throw dependent upon airflow rate, with minimum airflow dependent upon ∆Tsupply-room (eg turndown to 25-28%, neck reducer dependent, and down to ≈1 L/s/m2 @ ∆Tsupply-room ≈ -16 K).
	Fixed direction: horizontal discharge, 360° radial pattern (4-way blow).
	Square face shape: lay-in tile, suitable for standard ceiling grids of up to 600 x 600 mm2 or 24″ square.
	Radial face pattern:  flush face with Helical Swirl (HSC) vane pattern.
	Metal Face: Powder coated galvanised steel.

Options

	Smudge minimiser: CleanScreen™ air supply through optional perforated hub washes diffuser face with clean supply air, minimising diffuser face soiling due to air borne contaminants from the room. Patents pending.
	Sweat inhibitor: CleanScreen™ (patents pending) air supply through optional perforated hub washes diffuser face with dehumidified supply air, eliminating diffuser face condensation due to humid room air.
	Circular face shape: face diameter = 1.4 x DN, suitable for vertical, round ducting or an exposed connection box (cylindrical or square). Well suited to plaster board ceilings or freely suspended applications. Reduced face diameters available on request (not suitable for freely suspended applications).
	Perforated face pattern: square perforated face panel (down to 35% open area) to screen diffuser face.
	Neck reducers: reduce airflow duty.
	Blanking segments: provide 2-way or 3-way discharge patterns. May be combined with neck reducers.
	Plenum: square, side-entry rigid foam connection boxes with threaded rod fastenings, optionally with acoustic lining opposite spigot. Metal connection boxes (square or cylindrical) also available.
	Mounting Frame: suitable for framing a square ceiling cut-out. Compatible with HSC-FD-DN250_to_DN500-S only.
	Metal Face: stainless steel (for selected sizes only).

SMARTEMP Fixed Helical Swirl Diffuser HSC-FD

Available in selected markets as the LTG Helix-Deckendrallauslass ILH

Smarter Design / Smarter Engineering / SMARTAIR DIFFUSION™

SMARTEMP Fixed Helical Swirl Diffuser, type HSC-FD: designed for low-temperature VAV systems.

Fixed aperture, fixed blade ceiling swirl diffuser with high volume flow, low pressure loss, low noise and low turndown. Available with neck reducers and segment covers. Horizontal discharge, even when turned down. May be ceiling mounted or freely suspended.

Unique Fixed Swirl Blades

The Fixed Helical Swirl Diffuser is suitable for cold-air distribution (CAD) VAV systems due to the following three fixed swirl blade features that allow extended VAV turndown:

• Cambered leading edges – ensure airflow attachment (vanes do not stall)
• Helical-twist curvature – provides shallow discharge angle at vane tips
• Bell-mouth exit – creates strong Coanda-effect attachment to diffuser face

Supply air is discharged with high induction swirl in a fixed radial pattern and with strong Coanda attachment to the diffuser face, producing stable horizontal discharge into the space even when low supply air temperature airflow is turned down.

High Swirl Induction

High induction of the Fixed Helical Swirl Diffuser produces a strong increase in the mass flow rate of the supply air stream. It also produces strong discharge velocity decay. Consequently, at any given airflow rate, the Fixed Helical Swirl Diffuser is suitable both for long throws (due to the high momentum of the swirling supply air stream) and short throws (due to its low velocity). Additionally, strong supply air stream dilution with room air produces rapid supply air temperature equalisation with the room air temperature. Substantially uniform temperature distribution is produced with high levels of draught-free comfort in the space.

• Swirl Cooling

When cooling, air-change effectiveness (ACE) greater than 95% is typical, with premium comfort (ADPI ≥ 90%) being achieved even at a high maximum specific airflow rate of ≈15 L/s/m².

• Swirl Heating

Supply air stream temperature dilution also improves heating performance by reducing the buoyancy of the supply air stream.

Low-temperature VAV Turndown

The Fixed Helical Swirl Diffuser also achieves premium comfort during turndown of low-temperature VAV systems. For ADPI ≥ 90% at ∆T_supply-room ≈ -16 K, turndown to 25-28% (neck reducer dependent) may be achieved even at a low specific airflow rate of just 1 L/s/m².

Wide Flow Range & Discharge Pattern Options

Optional neck reducers for the Fixed Helical Swirl Diffuser are available to reduce the high airflow capacity of the diffuser to smaller design flow whilst largely preserving VAV range.

Additionally, segment covers are available to reduce the discharge pattern from 360° to 270°, 180° or 2 x 90° (ie from four-way to three-way or two-way blow).

CleanScreen™

Optional CleanScreen™ includes a perforated hub that discharges clean, dehumidified supply air to screen the diffuser face from soiling and condensation due to humid air and airborne contaminants in the space. CleanScreen™ enhances hygiene, maintains clean aesthetics, and effectively eliminates ongoing cleaning costs. CleanScreen™ is well suited to applications with a high concentration of pollutants (such as restaurants or near busy streets), in places of high humidity (such as the tropics or the coast) or where high infiltration may occur (such as lobbies and public spaces).

Construction

The Fixed Helical Swirl Diffuser is made of powder coated galvanised steel. Its swirl vanes form a flush surface with the surrounding diffuser face, which may be optionally screened by a perforated face (down to 35% open area).

The diffuser is available with a round (all sizes) or square face (sizes DN250 to DN500) and provides radial discharge that projects horizontally from the diffuser face. It may be flush mounted in a ceiling or freely suspended (the latter for round face variants and selected square face variants), and may be used in both CAV and VAV systems

Conclusion

The high induction of the Fixed Helical Swirl Diffuser offers many advantages. Intense mixing at the diffuser discharge surface strongly dilutes the swirling supply air stream with large quantities of room air. Rapid temperature equalisation of the supply air with room air is achieved, preventing cold air dumping and producing uniform temperature distribution with high comfort levels in the space.

Optimised for low-temperature VAV systems, the Fixed Helical Swirl Diffuser offers a wide VAV range of operation even in freely-suspended cold-air distribution applications.

SMARTEMP Fixed Helical Swirl Diffuser HSC-FD

Available in selected markets as the LTG Helix-Deckendrallauslass ILH

Smarter Design / Smarter Engineering / SMARTAIR DIFFUSION™

Unique features include:

• Extended turndown for low-temperature VAV systems due to swirl vanes with cambered leading edges, helical twist and bellmouth discharge.
• Low pressure drop reduces fan energy.
• High capacity airflow reduces architectural impact.
• Neck reducers allow common face size for uniform architecture.
• Neck reducers and segment covers provide adaptability to fitout changes.
• Flush face enhances aesthetics.

SMARTEMP HSC-FD registered designs, patent applications and granted patents are listed at smartemp.com/patents.

SMARTEMP Fixed Helical Swirl Diffuser HSC-FD

Available in selected markets as the LTG Helix-Deckendrallauslass ILH

Smarter Design / Smarter Engineering / SMARTAIR DIFFUSION™