Drum Displacement Diffuser

Smartemp DDF-FD

Cylindrically shaped displacement diffuser for placement on the floor.  Connection from above or below.

Displacement airflow
Thermal displacement room airflow, with low turbulent airflow supply into the occupancy microclimate. Heat and contaminants rise to a high layer of stratification by natural convection. Enhanced levels of indoor air quality are attained in the breathing zone.

Floor location
Protruding from the floor, typically at least 1 m from seated occupants.

Dependent throw VAV
Horizontal throw dependent upon VAV airflow rate.

Fixed direction
Air is discharged substantially horizontally from the perforated diffuser face.

Drum face shape
The diffuser face is cylindrical.

Perforated face pattern
The diffuser face is made of perforated sheet metal.

Metal Face
Powder coated metal finish.

Airflow rate

  • ​≤ 600 L/s [2160 m³/h]

Face velocity

  • ≤ 0.3 m/s

Coverage radius

  • 5 – 10 m

Sound power level

  • ≤ 35 dB(A)

Nominal sizes

  • DN250 (500 – 750 mm high)
  • DN315 (750 – 1000 mm high)
  • DN400 (1000 mm high)
  • DN500 (1000 mm high)


  • Robust, perforated metal drum discharge face
  • Inner perforated cylinder provides low turbulence airflow
  • Connection from above or below


The SMARTEMP Drum Displacement Diffuser, type DDF-FD, discharges low velocity supply air with fixed horizontal discharge direction in a radial pattern for displacement airflow supply in commercial spaces. Air supply across inner and outer perforated cylinders provides uniform, low turbulence discharge across the entire perforated drum-shaped face. High quality air oozes from the diffuser with minimal mixing, spreading radially to flood the floor with a lake of displacement airflow. A low level occupancy microclimate of enhanced indoor air quality is created in which convective currents from heat sources such as occupants, equipment and lights rise upwards, drawing in high quality replenishment air from the occupancy microclimate and enveloping heat sources in cooler, high quality air. Heat and contaminants stratify at a high level in concentrated form, where they are removed from the space. Due to stratification of heat, relatively large supply-to-return temperature differentials are achievable – dependent on ceiling height – despite the relatively high supply air temperature (typically 20°C), thereby minimising fan energy. Energy savings also accrue from the extended free cooling range typically achieved by the elevated supply air temperature, as well as from the potential to reduce outdoor airflow rates due to the enhanced indoor air quality resulting from the improved ventilation effectiveness of the low level displacement supply.

Product Type

Airflow Direction



Face Material

Face Pattern

Face Shape


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