Floor Diffuser - Halton

DSM 

Floor Diffuser 

20/DSM/3500/0606/EN 

• Low velocity under-seat air supply at an angle of 360 

degrees, for use in auditoriums, theatres, concert 

halls etc. 

• Comfortable, thermal and good acoustic conditions 

• Installation under seat; connected to pressurised 

under-floor plenum 

• Pressure drop of the diffuser enables self-balancing 

in most cases 

MATERIAL AND FINISHING 

PART MATERIAL FINISHING 

Diffuser Galvanised steel Epoxy-painted, Black RAL 9005 / White RAL 9010 

DSM - Floor Diffuser 

82

20/DSM/3500/0606/EN 

Function 

DIMENSIONS 

The DSM floor diffuser is designed for under-floor air 

distribution systems. 

Air is supplied into the space below the seats at a low 

velocity and at an angle of 360°. 

Supply air mixes with room air in the vicinity of the 

diffuser and rises up due to convection flows from the 

occupants. 

150 

96 

75 

200 

The perforated plate inside the coupling sleeve creates 

sufficient pressure loss to enable self-balancing. 

The recommended pressure level in the plenum 

chamber is 30 … 40 Pa. 

The recommended supply air temperature is max. 3°C 

lower than the room temperature. 

The supply airflow rate per unit is 12 … 16 l/s. 

205 

QUICK SELECTION 

qv l/s 12 14 16 18 20 22 24 26 

m 3 /h 43 50 58 65 72 79 86 94 

DSM-100 LpA < 10 11 13 16 19 21 24 27 

DPst 11 15 20 25 31 38 45 53 

DPtot 13 17 22 28 35 43 51 59 

LpA values presented with room attenuation 4 dB (red 10m 2 - sab). 

When using room attenuation 8 dB (red 25m 2 - sab): LpA - 4dB. 

LpA 

DPst 

DPtot 

A-weighted sound pressure level, reduced by total 

equivalent absorption surface of 10m 2 , dB(A) red 

0m 2 - sab 

Static pressure drop, Pa 

Total pressure drop, Pa 


83

Floor supply system design 

The DSM floor diffusers are designed for installation 

in raised floor systems like auditoriums, conference 

rooms, theatres, where a high level of comfort and 

conveyance is required. Supply air velocity must 

be very low to reduce discomfort that may be felt 

in the near zone. We recommend designing as 

a displacement system with a maximum supply 

temperature of 3°C below room. Supply 12 to 16 

l/s per unit and allow a distance between outlets 

of 0.8 to 1 meter. Where comfort requirements are 

less important, higher airflow rates can be used, 

generating increased velocities close to the diffuser. 

Discomfort may be felt if exposed for an extended 

period of time. 

In this case outlets should be installed at least 1.5 m 

from the work place or other continuously occupied 

areas. 

Connection of the diffusers 

The DSM is suitable for ductwork connection (figure 

1), but was specially designed to be installed without 

(figure 2). 

The space beneath the raised floor is used as a 

distribution plenum chamber. Construction includes a 

perforated cylinder inside the sleeve, which causes an 

efficient pressure loss and provides a self-balancing 

system. 

We recommend designing the system so that the 

pressure inside the plenum chamber will be 30 … 40 

Pa. 

Where the plenum chamber has a large volume, we 

recommended the use of multiple air introduction 

points (figure 2). 

20/DSM/3500/0606/EN 

Å Æ 

Å Æ 

Å Æ 

Å Æ 

Å Æ 

Å Æ 

10 ... 20 Pa 

ÅÆ 

ÅÆ 

Figure 1 Figure 2 


84

Velocity and temperature measurements 

1 2 3 

4 

5 6 7 

20/DSM/3500/0606/EN 

DSM-100 

Airflow rate qv = 14 l/s (50 m³/h) 

Supply temperature = 24 °C 

Room temperature = 27 °C 

ΔT 

= -3°C 

125 mm 125 mm 

225 mm 225 mm 

325 mm 325 mm 

HEIGHT mm 

DISTANCE mm 

-325 -225 -125 0 125 225 325 

700 0.04 m/s 26.1°C 0.03 m/s 26.1°C 0.06 m/s 26.0°C 0.04 m/s 25.0°C 0.03 m/s 26.3°C 





50 0.13 m/s 26.0°C 0.35 m/s 25.9°C 0.35 m/s 25.7°C 0.10 m/s 26.1 

DSM-100 

Airflow rate qv 18 l/s (65 m³/h) 

Supply temperature 22 °C 

Room temperature 25 °C 

ΔT - 3°C 

HEIGHT mm 

DISTANCE mm 

-325 -225 -125 0 125 225 325 






50 0.19 m/s 24.7°C 0.45 m/s 24.6°C 0.45 m/s 24.3°C 0.10 m/s 24.6 

DSM-100 

Airflow rate qv 22 l/s (79 m³/h) 

Supply temperature 23 °C 

Room temperature 26 °C 

ΔT - 3°C 

HEIGHT mm 

DISTANCE mm 

-325 -225 -125 0 125 225 325 






50 0.24 m/s 25.7°C 0.70 m/s 25.2°C 0.73 m/s 25.2°C 0.15 m/s 26.0 


85

Installation 

The DSM floor diffuser is installed into an installation 

hole with a diameter of 110 mm. 

The DSM is mounted onto the floor by screwing the 

pre-drilled attachment brackets into the slab. 

Servicing 

Detach the device by unscrewing the screws. 

Clean the parts by wiping them with a damp cloth, 

instead of immersing in water. 

Reattach the device by screwing it back onto the 

sleeve. 

Suggested Specifications 

The diffuser shall be made of galvanised steel, with 

black (RAL 9005) or white (RAL 9010) as standard 

colour. 

The perforated plate inside the coupling sleeve shall 

create sufficient pressure loss for a self-balancing in 

ductless applications. The space beneath the raised 

floor shall be used as a plenum chamber. 

Air distribution into the occupied zone shall be at a 

360° angle around the diffuser, and at low velocity 

without causing disturbance flows. 

20/DSM/3500/0606/EN 

Pressure drop and sound data 

DSM-100 

Product Code 

DSM-D 

D = Diameter of duct connection 

100 

Specifics and accessories 

CO = Colour 

B 

W 

Black 

White 

Code example 

DSM-100, CO=B 

Selection example : 

Requirements : qv = 20 l/s Selection : DSM-100 

LpA < 20 dB(A) 

DPtot = 35 Pa 

LpA < 18 dB(A) 

SOUND LEVEL DATA 

qv DPst DPtot F (Hz) LpA NR NC 

(l/s) (m 3 /h) (Pa) (Pa) 63 125 250 500 1000 2000 4000 8000 [dB(A)] 

DSM-100 18 65 24 27 30 28 17 17 11 7 10 7 15 12 9 

22 79 37 41 33 31 21 23 20 11 11 7 20 16 14 

26 94 50 57 35 33 24 27 27 14 11 7 25 23 21 

30 108 67 75 37 35 27 30 33 17 12 7 30 29 27 

34 122 86 97 39 37 29 34 39 19 12 7 35 35 33 

LpA values presented with room attenuation 4 dB (red 10m 2 - sab). When using room attenuation 8 dB (red 25m 2 - sab): LpA - 4dB. 

NR/NC noise criteria 


86

Floor Diffuser - Halton

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