Lindab 1 General information and theory 2 Safe 3 Silencers 4 Dampers & Measure units 5 Fire dampers & Smoke evacuation 6 Air valves 7 Roof hoods 8 Other circular products 9 Transfer 10 Rectangular 11 Flexible ducting 12 Isol 13 Access doors 14 Smart tools 15 Duct suspensions & Support systems 16 Fastening material 17 Index 18 Silencers lindab | silencers
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lindab | silencers Silencersitsolution.lindab.com/.../ADS/hu/Technical/04-Silencers-ads.pdf · The silencers are of the absorption silencer type. The damping ability of absorption
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Lindab 1
General information and theory 2
Safe 3
Silencers 4
Dampers & Measure units 5
Fire dampers & Smoke evacuation 6
Air valves 7
Roof hoods 8
Other circular products 9
Transfer 10
Rectangular 11
Flexible ducting 12
Isol 13
Access doors 14
Smart tools 15
Duct suspensions & Support systems 16
Fastening material 17
Index 18
Silencers
l indab | silencers
170 We reserve the right to make changes without prior notice
DesignThe straight types consist of an outer and inner sheet cas-ing. The space between them is filled with mineral wool of varying type and density. The outer sheet casing of the circular curved silencers are built as a segmented bend, BFU.
Baffles, one or more, for better noise attenuation, exist in SLCBU, SLBGU, LRBCB.The tear of fibre is prevented since all exposed surfaces are lined. The connections of the circular types are supplied with a Safe-gasket.
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l indab | silencers
General The silencers are of the absorption silencer type. The damping ability of absorption silencers is affected by the geometric design of the silencer and the type of damping material chosen. Silencer comprises a total of 17 such vari-ants, with different properties. The graph below summarises the attenuation of some types of silencer.
More information about damping in duct systems, and dimensioning and calculation examples can be found on page 28.
Method of measurementThe silencers are tested in accordance with ISO 7235 ”Acoustics - Measurement procedures for ducted silencers - Insertion loss, flow noise and total pressure loss”.
Type approvalThe type approved variants are approved on the aspects of fire and tightness according to the certificate nr 0015/05.
Cleaning of duct systemsSilencers with baffles have parts which block the duct sys-tem to a greater or lesser extent, and thus obstruct or pre-vent cleaning of the duct system. Please refer to page 603.
Fire class alternativesThe Building Regulations, BBR, from the Swedish National Board of Housing, Building and Planning contains the fol-lowing paragraph about exchange of fire classes.
5:6213 Fire class alternativesFire class EI can be exchanged to class E, if the distance to escape route and to combustable material is sufficient not to deteriorate the safety of escape nor the risk for fire spread to increase.
This means that e.g. a silencer with E-class can be used where there is a demand for EI-class under the presumption that some specified time periods and protective distance is achieved.
We specify these time periods and protective distances for our products.
Radiation at fireObjects, subjected to radiation, are often divided into three categories. Their maximum allowed radiation intensity levels are:People during evacuation 3 kW/m²Fitting materials, curtains, drapes etc. 10 kW/m²Building materials, wood etc. 30 kW/m²
The longer the distance from a radiation source is the lower the radiation intensity level.
We specify these radiation intensity levels and correspond-ing protective distances for our products.
Protective distanceProtective distance is the shortest distance that is allowed between the silencer and evacuation person or combustible materials.
0
10
20
30
40
50
63 125 250 500 1k 2k 4k 8k
SLCBU 315 600 10
BSLCU 315 100
SLGU 315 600 100
SLCU 315 600 50
[dB]
Loud- speaker chamber
Substitution duct
Silencer under test
Reverberatio 30 kW/m² 3 kW/m²10 kW/m²
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Circular straight silencer
l indab | silencers
DescriptionCircular straight silencer.Insulation thickness 50 mm (Ø 63–250).
We reserve the right to make changes without prior notice 183
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Circular straight silencer with baffle
l indab | silencers
PVAP
Technical data
Ø400
Ø500
Ø630
Ø800
Ø1000
Ø1250
Ø400
Ø500
Ø630
Ø800
Ø1000
Ø1250
0,5 1 2 3 4 5 6 7 8 9 10 20 30
0,5 1 2 3 4 5 6 7 8 9 10 20 30 m3/s
m3/s
200
100
1010
0
20
30
40
506070
200
100
1010
0
20
30
40
506070
ΔPt (P
a)ΔP
t (Pa)
Ø400 - 630 L = 600 mm, Ø800 - 1250 L = d
Ø400 - 630 L = 1200 mm, Ø800 - 1250 L = 2 x d
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Circular straight low-built silencer LRCA
184 We reserve the right to make changes without prior notice
l indab | silencers
DescriptionSilencer with low installation height. LRCA has a bowl-shaped mineral wool insultion with a fibre cloth in order to prevent tear off mineral wool. Can achieve maximum tight-ness class C.
We reserve the right to make changes without prior notice 189
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Circular straight low-built silencer
l indab | silencers
DescriptionSilencer with low installation height.
The silencer’s insertion loss material is Acutec ® (polyester).
Dimensions
Sound power levels per octave band LWo are calculated by adding the octave band corrections Koct to the total power level LWA from the graphs. LWo = LWA + Koct
Ordering exampleKVDP 125 1000
ProductDimension Ød1Length l
Ød1nom
lmm
amm
bmm
Attenuation [dB] for centre frequency [Hz]
mkg63 125 250 500 1k 2k 4k 8k
63 300 162 75 1 7 10 13 16 23 21 22 1,10
63 600 162 75 5 10 15 19 23 32 33 39 1,85
80 300 180 97 1 5 9 9 15 20 16 15 1,25
80 600 180 97 5 8 12 15 21 28 31 31 2,05
100 300 252 154 6 5 9 14 15 9 9 10 3,46
100 600 252 154 12 11 13 19 29 26 22 22 5,72
100 1000 252 154 16 14 18 28 39 36 34 38 8,91
125 300 263 177 7 4 7 15 12 8 11 10 3,50
125 600 263 177 12 8 10 20 28 20 20 19 6,10
125 1000 263 177 17 11 14 26 35 31 31 30 9,50
160 300 280 212 6 4 6 15 9 7 10 6 4,12
160 600 280 212 12 6 8 19 29 20 19 19 6,74
160 1000 280 212 15 10 12 25 31 27 27 22 10,1
200 300 361 253 5 3 7 13 8 6 6 6 5,82
200 600 361 253 7 6 11 20 18 12 11 12 8,55
200 1000 361 253 10 10 15 25 31 21 18 19 12,3
250 600 431 303 6 6 11 20 14 13 12 10 10,7
250 1000 431 303 7 9 14 24 25 20 19 16 14,6
315 600 458 368 3 5 11 17 11 10 9 7 13,1
315 1000 458 368 4 8 13 24 20 16 14 10 18,0
Size
Correction Koct [dB] for centre frequency [Hz]
63 125 250 500 1k 2k 4k 8k
100 2 6 1 -2 -5 -14 -21 -35
125 2 4 2 -1 -7 -12 -18 -31
160 5 4 1 -1 -6 -10 -17 -30
200 4 4 4 -1 -9 -13 -20 -31
250 5 3 1 -2 -5 -10 -16 -28
315 7 5 2 -3 -5 -11 -17 -30
400 6 6 2 -1 -7 -14 -20 -35
Tol.+/- 4 3 3 3 3 4 3 4
l
Ød
1
a
b
KVDP
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Circular straight low-built silencer KVDP
l indab | silencers
Technical data300 mm
600 mm
1000 mm
Δpt
[Pa]
q
10 20 30 50 100 200 500 10002
3
5
10
20
30
50
3
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6
78
[l/s]
LWA[dB]
Ø [mm]
v [m/s]
100
8063 125
160
200
25
30
35
40
45
50
q
10 20 30 50 100 200 500 1000
Δ
pt
2
3
5
10
20
30
50
100
8063 125
160
200
250
315
25
30
35
40
45 50
3
4
5
6
78
[Pa]
[l/s]
LWA [dB]
Ø [mm]
v [m/s]
q
10 20 30 50 100 200 500 1000
Δp
t
2
3
5
10
20
30
50
25
30
35
40
45 50
3
4
5
6
78
[Pa]
[l/s]
LWA [dB]
v [m/s]
100
125
160
200
250
315
Ø [mm]
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Circular (Rect) silencer
l indab | silencers
KVDP 90K
DescriptionCompact angled silencer with good attenuation.
The silencer’s measurments makes it suitable for installation above suspended ceilings or where installation space is lim-ited.
The silencer’s insertion loss material is Acutec ® (polyester).
192 We reserve the right to make changes without prior notice
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Circular (Rect) silencer KVDP 90K
l indab | silencers
Technical data
qv (l/s)
Ø 1
00
Ø 1
25
Ø 1
60
Ø 2
00
Lw 45 dB (A)
2 m/s
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5
20
50
20
10
5
2
10 20 30 50 100 200 500
ΔP
t (Pa)
40
50
35
30
25
Lw 45 dB (A)
2 m/s
3
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5
20
50
20
10
5
2
10 20 30 50 100 200 500
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50
35
30
25
L = 1000 mm
L = 600 mm
ΔP
t (Pa)
Ø 1
00
Ø 1
25
Ø 1
60
Ø 2
00
qv (l/s)
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Circular (Rect) silencer
l indab | silencers
KVDP 90L
DescriptionCompact angled silencer with good attenuation.The silencer’s measurments makes it suitable for installation above suspended ceilings or where installation space is lim-ited.
The silencer’s insertion loss material is Acutec ® (polyester).
194 We reserve the right to make changes without prior notice
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Circular (Rect) silencer KVDP 90L
l indab | silencers
Technical data
Ø 1
00
Ø 1
25
Ø 1
60
Ø 2
00
50
20
10
5
2
10 20 30 50 100 200 500
50
20
10
5
2
10 20 30 50 100 200 500
L = 1000 mm
L = 600 mm
Ø 1
00
Ø 1
25
Ø 1
60
Ø 2
00
Lw 45 dB (A)
2 m/s
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30
25
Lw 45 dB (A)
2 m/s
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20
40
35
30
25
qv (l/s)
ΔP
t (Pa)
ΔP
t (Pa)
qv (l/s)
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Circular curved silencer
l indab | silencers
DescriptionLack of space is a frequent problem in air treatment installa-tions. This means that it is often difficult to find enough straight lengths to install a straight silencer.
This problem can be eliminated by installing a curved silencer.
For the same length, it mostly has better attenuation than the equivalent straight silencer. In particular, you get better attenuation at high frequencies (4 and 8 kHz).
196 We reserve the right to make changes without prior notice
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Circular curved silencer BSLU 100
l indab | silencers
DescriptionLack of space is a frequent problem in air treatment installa-tions. This means that it is often difficult to find enough straight lengths to install a straight silencer.
This problem can be eliminated by installing a curved silencer.
For the same length, it mostly has better attenuation than the equivalent straight silencer. In particular, you get better attenuation at high frequencies (4 and 8 kHz).
We reserve the right to make changes without prior notice 197
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Circular curved silencer
l indab | silencers
DescriptionLack of space is a frequent problem in air treatment installa-tions. This means that it is often difficult to find enough straight lengths to install a straight silencer.This problem can be eliminated by installing a curved silencer.For the same length, it mostly has better attenuation than the equivalent straight silencer. In particular, you get better attenuation at high frequencies (4 and 8 kHz).
Fire classes without protective distance: EI 30, E 120
Fire classes with protective distance to: evacuation person:
3 kW/m² EI 120 at distance 50 mmcombustible materials:
10 kW/m² EI 120 at distance 5 mm30 kW/m² EI 120 at distance 5 mm
198 We reserve the right to make changes without prior notice
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Circular curved silencer BSLCU 100
l indab | silencers
DescriptionLack of space is a frequent problem in air treatment installa-tions. This means that it is often difficult to find enough straight lengths to install a straight silencer.
This problem can be eliminated by installing a curved silencer.
For the same length, it mostly has better attenuation than the equivalent straight silencer. In particular, you get better attenuation at high frequencies (4 and 8 kHz).
Fire classes without protective distance: EI 60, E 120
Fire classes with protective distance to:evacuation person:
3 kW/m² EI 120 at distance 50 mmcombustible materials:
10 kW/m² EI 120 at distance 5 mm30 kW/m² EI 120 at distance 5 mm
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Exhaust air terminal device
l indab | silencers
DescriptionSLKNU is an exhaust air terminal device consisting of a silencer with 50 mm insulation and conical inlet with net.
Material and surface treatmentSLKNU is manufactured from galvanized sheet metal and is as standard delivered non-painted. The device can also be painted to order.
CapacityAir flow q [l/s] and [m³/h], total pressure Δpt [Pa] and sound pressure level LW [dB(A)] is read in the graph.
Dimensions
Self attenuation ΔLThe device's self attenuation from duct to room inclusive end reflexion.
200 We reserve the right to make changes without prior notice
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Exhaust air terminal device SLKNU 100
l indab | silencers
DescriptionSLKNU is an exhaust air terminal device consisting of a silencer with 100 mm insulation and conical inlet with net.
Material and surface treatmentSLKNU is manufactured from galvanized sheet metal and is as standard delivered non-painted. The device can also be painted to order.
CapacityAir flow q [l/s] and [m³/h], total pressure Δpt [Pa] and sound pressure level LW [dB(A)] is read in the graph.
Dimensions
Self attenuation ΔLThe device's self attenuation from duct to room inclusive end reflexion.
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Silencer SLRS
l indab | silencers
DescriptionRectangular straight silencer from the Aerodim™ series.SLRS is built with the Aerodim™ silencer splitter SLRA.The silencer SLRA is manufactured with a frame of galva-nized sheet and absorption material type Lindtec™. TheLindtec™ surface is easy to clean and prevents removal offibres.
Due to the aerodynamic design, the SLRS has a lowpressure loss and a low generation of flow noise. The splitteris available in a width of 200 mm. The SLRS is also availablein other lengths and with other splitter distances than shownin the tables. To calculate the silencer, you can use our IT-program DIMsilencer, where splitter distance, length andheight can be optimized for the best performance.
Dimensions
Technical data
NB. Max. attenuation specified is 50 dB.The pressure loss Δp in Pa can be calculated from the pres-sure value ξ: Δp = 0,6 × v2 × ξ where (v) is the velocity on the face area of the silencer.
The lengths shown above are only examples, other lengths between are also available. Min. length is 500 mm. Maxi-mum length is 2500 mm. Lengths over 2500 mm. will be divided up into two or more silencers.
Ordering exampleSLRS 200 100 1200 900 1000 LS
ProductSplitter width in mmSplitter distance in mm.a in mmb in mml in mmConnection type, e.g. LS
a
b
l
S ½ s
Flow
Splitter distance S = 60 mmLength
mmAttenuation [dB] for centre frequency [Hz] Pressure
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Silencer SLRS
l indab | silencers
Technical data
Lwi
Lwo
Lwo
Lwi
Inlet
Outlet
Supply
Exhaust
Surroundings Room
The flow noise and pressure loss is dependent on the velo-city (v) on the face area(A) of the silencer.
However, the noise generated at the inlet of the silencer Lwi is higher than the noise generated at the outlet of the silencer Lwo. It is therefore crucial to use the correct value depend on the placement of the silencer in the duct sys-tem, cf. drawing.
When calculating the silencer for:• supply and outlet - use outlet noise Lwo• inlet and exhaust - use inlet noise Lwi
Sound power level, inlet: Lwi Sound power level, outlet: Lwo
s=60 m
m
s=80 m
m
s=100 m
m
s=120 m
m
s=140 m
m
0
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20
30
40
50
60
dB(A
)
v (m/s)0 1 2 3 4 5 6 7 8 9
A [m²]Kor.
0,9 1,0 2,0 3,00,5-3
0,7-2
0,8-2 -1 0 2 3
4,05 6
5,00,67
0
10
20
30
40
50
60dB
(A)
s=60
mm
s=80
mm
s=10
0 m
ms=
120
mm
s=14
0 m
m
v (m/s)0 1 2 3 4 5 6 7 8 9
A [m²]Kor.
0,9 1,0 2,0 3,00,5-3
0,7-2
0,8-2 -1 0 2 3
4,05 6
5,00,67
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Silencer SLRS
l indab | silencers
Calculation examplePressure loss and flow noise depend on the velocity onthe face area of the silencer A.
This is illustrated in the following example:SLRS 900x600 mm, Length 1.5 metre3 splitters, distance 100 mm.
Flow = 7776 m3/h = 2.16 m3/s.Area A = 0.9 m × 0.6 m = 0.54 m2
Pressure loss:Pressure loss = 39 Pa.
Flow noise from inlet:Lwi = 44 dB(A) -3 = 41 dB(A)(-3 from area korrection)
Flow noise from outlet:From graph:Lwo = 36 dB(A) -3 = 33 dB(A)(-3 from area korrection)
Pressure loss
Sound power level, inlet: Lwi
Sound power level, outlet: Lwo
Face velocity =2,16 m3/s0,54 m2
= 4 m/s
0
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v (m/s)
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50
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100
Pa
L=1,0 mL=1,5 mL=2,0 mL=2,5 m
s=100 mm
0 1 2 3 4 5 6 7 8 9
0
10
20
30
40
50
60
dB (A
)
v (m/s) 0 1 2 3 4 5 6 7 8 9
A [m²] Kor.
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0,7 -2
0,8 -2 -1 0 2 3
4,0 5 6
5,0 0,6 7
s=100 mm
0
10
20
30
40
50
60
dB
(A)
v (m/s) 0 1 2 3 4 5 6 7 8 9
A [m²] Kor.
0,9 1,0 2,0 3,0 0,5 -3
0,7 -2
0,8 -2 -1 0 2 3
4,0 5 6
5,0 0,6 7
s=100 mm
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Silencer splitter SLRA
l indab | silencers
DescriptionSLRA is the basic element in the Aerodim™ silencer series.
The SLRA is manufactured with a frame of galvanized sheet and absorption material type Lindtec™. The Lindtec™ sur-face is easy to clean and prevents removal of fibres. Due to the aerodynamic design, the SLRA has a low pressure loss and a low generation of flow noise. The SLRA is available in a width of 200 mm. The SLRA is also available in other leng-hts and with other splitter distances than shown in the tabels.To calculate the silencer, you can use our IT-program DIMsilencer, where splitter distance, length and height can be optimized for the best performance.
Dimensions
Technical data
NB. Max. attenuation specified is 50 dB.
The pressure loss Δp in pa can be calculated from the pres-sure value ξ: Δp = 0,6 × v2 × ξ where (v) is the velocity on the face area of the silencer.
The lengths shown above are only examples, other lengths between are also available. Min. length is 500 mm. Maxi-mum length is 2500 mm.
Be aware that, l nom means, that the length in the Order examples normaly are ment as the length of the duct, the splitter will be a bit shorter to prevent mounting problems.
200 l
b
200
b
S½s
l
Flow
Ordering exampleSLRA 200 600 1000
ProductSplitter width in mmb in mml nom. in mm.
Splitter distance S = 60 mmLength
mmAttenuation [dB] for centre frequency [Hz] Pressure
206 We reserve the right to make changes without prior notice
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Rectangular straight silencer DLD
l indab | silencers
DescriptionDLD has a conventional design with dimensions that not exceed the corresponding connection dimensions. The silencer can be manufactured in all standard duct sizes.
DesignDLD has an outer sheet casing of trapezoidal corrugated sheet metal for stability and reduced risk of natural oscilla-tion.DLD is designed for low air resistance with baffle combina-tions that attenuate particularly low-frequency noise well.The type of insulation material has been developed to pro-vide good noise properties, low weight and to be cleanable.
DLD meets the requirements of air tightness class C and pressure class 2 according to EN 1507:2006.
DLD is equipped with joining profile type RJFP.
Tools for dimensioning and planningThe software CADvent and DIMsilencer offer features for dimensioning and selection of products in an environment with 3D modelling. Computerised planning can be con-ducted with automatic presentation of noise levels, pressure drop etc.
Dimensions
If alternative material is required, this shall be stated when ordering, e.g. aluminium zinc (AZ185), stainless (2333) and acid-proof steel (2343).
The silencer is also available with the following accessories/ options.
TRA = Non-insulated inspection hatch.TRB = Hatch intended for external insulation.* TRC = Hatch intended for external insulation.*AIA = 50 mm fire protection insulation. Note! a and
b dimensions increase by 100 mm.AIB = 100 mm fire protection insulation. Note! a and
b dimensions increase by 200 mm.AIA+TRB = 50 mm fire protection insulation and the
appropriate cleaning cover. Note! a and b dimensions increase by 100 mm.
AIB+TRC = 100 mm fire protection insulation and the appropriate cleaning cover. Note! a and b dimensions increase by 200 mm.
The dimension of the hatches is adapted for cleaning and inspection of all baffle spacings.
* Specify insulation thickness when ordering.
b
a
l
Ordering exampleDLD 800 × 600 650 1015 TRA
ProductWidth height a × bLength lCodeAccessories
Rectangular straight silencer DLD
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Rectangular straight silencer DLDR
l indab | silencers
DescriptionDLDR has a conventional design with dimensions that not exceed the corresponding connection dimensions. The silencer can be manufactured in all standard duct sizes.
The silencer is provided with cleaning hatch and removable baffles.
DesignDLDR has an outer sheet casing of trapezoidal corrugated sheet metal for stability and reduced risk of natural oscilla-tion.DLDR is designed for low air resistance with baffle combina-tions that attenuate particularly low-frequency noise well.The type of insulation material has been developed to pro-vide good noise properties, low weight and to be cleanable.
DLDR meets the requirements of air tightness class C and pressure class 2 according to EN 1507:2006.
DLDR is equipped with joining profile type RJFP.
Tools for dimensioning and planningThe software CADvent and DIMsilencer offer features for dimensioning and selection of products in an environment with 3D modelling. Computerised planning can be con-ducted with automatic presentation of noise levels, pressure drop etc.
Dimensions
If alternative material is required, this shall be stated when ordering, e.g. aluminium zinc (AZ185), stainless (2333) and acid-proof steel (2343).
The silencer is also available with the following accessories/ options.
TRB = Hatch intended for external insulation.* TRC = Hatch intended for external insulation.*AIA = 50 mm fire protection insulation. Note! a and
b dimensions increase by 100 mm.AIB = 100 mm fire protection insulation. Note! a and
b dimensions increase by 200 mm.
The dimension of the hatches is adapted for cleaning and inspection of all baffle spacings.
* Specify insulation thickness when ordering.
a
bl
Ordering exampleDLDR 800 × 600 750 1015 1 TRB
ProductWidth height a × bLength lCodeAlternative for placing of hatch(Alt 1 on top, alt 2 on side, alt 3 on bottom.) Accessories
Rectangular straight silencer DLDR
208 We reserve the right to make changes without prior notice
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Rectangular straight silencer DLD/DLDR
l indab | silencers
Manual designing for DLD and DLDRA number of silencers can be designed manually, for more combinations of silencers and faster calculations use DIMsilencer. Manual method of calculation is shown below:
A Specify connection dimensions and flow-type location of the silencer.
B Specify the sound power level before the silencer.Read the insertion attenuation from the tables on page 6 – 9.Calculate the sound power level after the silencer irrespective of the air flow (selv generated noise).
Insertion attenuation
C Determine the pressure drop with help of the graph on page 3 and table on page 4.In this case we have straight ducts before and after the silencer.
Pressure drop
D Determine the self generated noise from the silencer at present air flow.Calculate the sound power level after the silencer inclusive the self generated noise.
Self generated noise
Width 800 mmHeigh 1000 mmLength 1250 mmLocation Exhaust air
Sound power level after silencer without self generated noise
69 64 57 41 39 42 40 35
Area 0,8 m² Air flow 400 l/sGraph on page 3, use resistance number, area and air velocity
Air velocity5 m/s
Pressure drop42 Pa
Correction at disturbance according table on page 4 Factor1
Pressure dropafter correction
42 Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 5, use resistance number and air velocity
59 55 54 51 48 45 41 35
Correction for gross cross section area -1 -1 -1 -1 -1 -1 -1 -1Self generated noise 58 54 53 50 47 44 40 34Sound power level after the silencer 69 64 58 51 48 46 43 38(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
Rectangular straight silencer DLD/DLDR
We reserve the right to make changes without prior notice 209
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Rectangular straight silencer DLD/DLDR
l indab | silencers
The following table can be used for own manual calculations in accordance with the example on the previous page.
number inletSound power level before silencerAttenuation from table page 6 – 9Sound power level after silencer without self generated noise
Area m² Air flow l/sGraph on page 3, use resistance number, area and air velocity
Air velocity m/s
Pressure drop Pa
Correction at disturbance according table on page 4 Factor Pressure dropafter correction
Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 5, use resistance number and air velocityCorrection for gross cross section areaSelf generated noiseSound power level after the silencer(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
Rectangular straight silencer DLD/DLDR
210 We reserve the right to make changes without prior notice
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Rectangular straight silencer DLD/DLDR
l indab | silencers
Pressure dropFollow the directions below and the adjoining graph.
Calculate the gross cross section area a × b in m².
Go horizontal in the graph to the present air flow, l/s.
Go up to the resistance number achieved from the tables on page 205 – 208.
Read the pressue drop over the silencer, at straight duct connection before and after the silencer, (factor 1,0). For other modes of connection see the table for correction on page 203.
Air flow velocity, which is used at the calculation of the self generated noise, can be read here.
1
2
3
4
5
4 5 6 7 8321 910
54
3
2
0,1
0,2
0,3
0,40,5
1
1,5
v [m/s]
Ac
[m²]
200
150
10
15
20
30
40
50
60708090
100
Δpt [
Pa]
1
5
2
3
4
R
30 20 15 10 8 64 3 2
1,5
1
30000200001500010000600040003000
200015001000
600400300
200150
q [l/s]
Rectangular straight silencer DLD/DLDR
We reserve the right to make changes without prior notice 211
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Rectangular straight silencer DLD/DLDR
l indab | silencers
Pressure dropPresent pressure drop = Read pressure drop × below factorD = The largest connection side (a or b) of the silencer.
The table contains of a selection of the most common disturbance cases.
Distance before the silencer Distance after the silencer
Silencer After the silencer
Factor
[dB]
[dB]
Incr
eam
ent t
o ad
d to
the
high
est d
B-v
alue
3
2
1
00 5 8 10
Difference between dB-values to be added
15 20
DLD/DLDR
212 We reserve the right to make changes without prior notice
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2
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Rectangular straight silencer DLD/DLDR
l indab | silencers
Self generated noise per frequence band Decide from the location of the silencer whether it is the supply or exhaust graph that shall be used. (Rule of mem-ory - the side that leads away from the fan, i.e. at supply air the outlet graph is used and at exhaust air the in-take graph.)
Go horizontally into the present graph, at present air ve-locity, to the self generated noise number.
Then go vertically up to the crossing of the different fre-quency band lines.
Read the self generated noise, at gross cross section area 1 m², for each frequency band straight out to the left. In the example only the 8000 Hz-reading is shown.
Add or subtract the correction for the present gross cross section area.
Sound power level after the silencerThe sound power level after the silencer can be calculated for all frequences by a logarithmical addition of:
”The self generated noise” and ”The sound power level before the silencer”.
The shown example gives at 8000 Hz:
Self generated noise = 35 dB - 1 dB = 34 dB
Sound power level before the silencer - the attenuation: 44 dB - 9 dB = 35 dB
Logarithmic addition of 34 and 35 = 36 dB
(See graph for logarithmical addition on page 4.)
-10,0
0,0 10,0
-10,0
0,0 10,0
Self generated noise in intake DLD/DLDR/DLDY Self generated noise in outlet DLD/DLDR/DLDY
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)A
ir ve
loci
ty(V
eloc
ity o
ver
gros
s cr
oss
sect
ion
area
.)
Air
velo
city
(Vel
ocity
ove
r gr
oss
cros
s se
ctio
n ar
ea.)
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)
Correction for gross cross section area:a × b in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
Correction for gross cross section area:a × b in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
dB(A)
63 Hz
125 Hz250 Hz
500 Hz
1 kHz
2 kHz
4 kHz 8 kHz
1,5
2
3
4
5 6 7 8 9 10
10 m/s
5 m/s
3 m/s
2 m/s
5 m/s
3 m/s
2 m/s
10 m/s
70 dB
60 dB
50 dB
40 dB
30 dB 30 dB
70 dB
60 dB
50 dB
40 dB
dB(A)
63 Hz
125 Hz
250 Hz
500 Hz1 kHz
2 kHz 4 kHz 8 kHz
1,5
2
3
4
5 6 7 8 9 10
Self generated noise number
Self generated noise number
10
9
8
7
6
Outdoor air
Extract air
Supplyair
Exhaust air
OutletRoom
Intake
Out-doors
Fan
Fan IntakeOutlet
7
8
9
10
DLD/DLDR
We reserve the right to make changes without prior notice 213
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Rectangular straight silencer DLD/DLDR
l indab | silencers
Width amm
Code
Length l mm Static insertion attenuation / octave band [dB]
We reserve the right to make changes without prior notice 217
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Rectangular straight silencer DLDY
l indab | silencers
DescriptionDLDY is fitted with built-in side baffles located outside the fitting dimensions. The products can be manufactured in all standard duct sizes.
DesignDLDY has an external shell of trapezoidal corrugated sheet for stability and reduced risk of natural oscillation.DLDY is designed for low air resistance with baffle combina-tions that dampen particularly low-frequency noise well.The type of insulation material is Lindtec which has been developed to provide good noise properties, low weight and to be cleanable.
DLDY meets the requirements of air tightness class C and pressure class 2 according to EN 1507:2006.
DLDY is equipped with joining profile type RJFP.
Tools for dimensioning and planningThe software DIMsilencer is recommended for fast choise of silencer or a complete and fast sound calculation of the duct system.The software CADvent offers dimensioning in an environ-ment with 3D-modelling.Computorised planning can be conducted with automatic presentation of noise levels, pressure drop etc.
Dimensions
If alternative material is required, this shall be stated when ordering, e.g. aluminium zinc (AZ185), stainless (2333) and acid-proof steel (2343).
The silencer is also available with the following accessories/ options.
TRA = Non-insulated inspection hatch.TRB = Hatch intended for external insulation.* TRC = Hatch intended for external insulation.*AIA = 50 mm fire protection insulation. Note! a and
b dimensions increase by 100 mm.AIB = 100 mm fire protection insulation. Note! a and
b dimensions increase by 200 mm.AIA+TRB = 50 mm fire protection insulation and the
appropriate cleaning cover. Note! a and b dimensions increase by 100 mm.
AIB+TRC = 100 mm fire protection insulation and the appropriate cleaning cover. Note! a and b dimensions increase by 200 mm.
The dimension of the hatches is adapted for cleaning and inspection of all baffle spacings.
* Specify insulation thickness when ordering.
a
a + 200
bl
5050
Ordering exampleDLDY 800 × 600 650 2015 TRA
ProductWidth height a × bLength lCodeAccessories
Rectangular straight silencer DLDY
218 We reserve the right to make changes without prior notice
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Rectangular straight silencer DLDY
l indab | silencers
Manual designing for DLDYA number of silencers can be designed manually, for more combinations of silencers and faster calculations use DIMsilencer. Manual method of calculation is shown below:
A Specify connection dimensions and flow-type location of the silencer.
B Specify the sound power level before the silencer.Read the insertion attenuation from the tables on page 211 – 215.Calculate the sound power level after the silencer irrespective of the air flow (selv generated noise).
Insertion attenuation
C Determine the pressure drop with help of the graph on page 208 and table on page 209.In this case we have straight ducts before and after the silencer.
Pressure drop
D Determine the self generated noise from the silencer at present air flow.Calculate the sound power level after the silencer inclusive the self generated noise.
Self generated noise
Width 800 mmHeigh 1000 mmLength 1350 mmLocation Exhaust air
Sound power level after silencer without self generated noise
69 62 54 33 27 33 33 30
Area 0,8 m² Air flow 400 l/sGraph on page 208, use resistance number, area and air velocity
Air velocity5 m/s
Pressure drop42 Pa
Correction at disturbance according table on page 209 Factor1
Pressure dropafter correction
42 Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 210, use resistance number and air velocity
59 55 54 51 48 45 41 35
Correction for gross cross section area -1 -1 -1 -1 -1 -1 -1 -1Self generated noise 58 54 53 50 47 44 40 34Sound power level after the silencer 59 63 57 50 47 44 41 35(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
Rectangular straight silencer DLDY
We reserve the right to make changes without prior notice 219
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Rectangular straight silencer DLDY
l indab | silencers
The following table can be used for own manual calculations in accordance with the example on the previous page.
number inletSound power level before silencerAttenuation from table page 211 – 215Sound power level after silencer without self generated noise
Area m² Air flow l/sGraph on page 208, use resistance number, area and air velocity
Air velocity m/s
Pressure drop Pa
Correction at disturbance according table on page 209 Factor Pressure dropafter correction
Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 210, use resistance number and air velocityCorrection for gross cross section areaSelf generated noiseSound power level after the silencer(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
220 We reserve the right to make changes without prior notice
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Rectangular straight silencer DLDY
l indab | silencers
Pressure dropFollow the directions below and the adjoining graph.
Calculate the gross cross section area a × b in m².
Goo horizontal in the graph to the present air flow, l/s.
Go up to the resistance number achieved from the tables on page 211 –215.
Read the pressue drop over the silencer, at straight duct connection before and after the silencer, (factor 1,0). For other modes of connection see the table for correction on page 209.
Air flow velocity, which is used at the calculation of the self generated noise, can be read here.
1
2
3
4
5
4 5 6 7 8321 910
54
3
2
0,1
0,2
0,3
0,40,5
1
1,5
v [m/s]
Ac
[m²]
200
150
10
15
20
30
40
50
60708090
100
Δpt [
Pa]
1
5
2
3
4
R
30 20 15 10 8 64 3 2
1,5
1
30000200001500010000600040003000
200015001000
600400300
200150
q [l/s]
We reserve the right to make changes without prior notice 221
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Rectangular straight silencer DLDY
l indab | silencers
TryckfallAktuellt tryckfall = Avläst tryckfall × nedanstående faktor.D = Ljuddämparens största anslutningssida (a eller b).
Tabellen omfattar ett urval av de vanligaste förekommande störningsfallen.
Distance before the silencer Distance after the silencer
Silencer After the silencer
Factor
[dB]
[dB]
Incr
eam
ent t
o ad
d to
the
high
est d
B-v
alue
3
2
1
00 5 8 10
Difference between dB-values to be added
15 20
222 We reserve the right to make changes without prior notice
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2
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Rectangular straight silencer DLDY
l indab | silencers
Self generated noise per frequence band Decide from the location of the silencer whether it is the supply or exhaust graph that shall be used. (Rule of mem-ory - the side that leads away from the fan, i.e. at supply air the outlet graph is used and at exhaust air the in-take graph.)
Go horizontally into the present graph, at present air ve-locity, to the self generated noise number.
Then go vertically up to the crossing of the different fre-quency band lines.
Read the self generated noise, at gross cross section area 1 m², for each frequency band straight out to the left. In the example only the 8000 Hz-reading is shown.
Add or subtract the correction for the present gross cross section area.
Sound power level after the silencerThe sound power level after the silencer can be calculated for all frequences by a logarithmical addition of:
"The self generated noise" and "The sound power level before the silencer".
The shown example gives at 8000 Hz:
Self generated noise = 35 dB - 1 dB = 34 dB
Sound power level before the silencer - the attenuation: 44 dB - 14 dB = 30 dB
Logarithmic addition of 34 and 30 = 35 dB
(See graph for logarithmical addition on page 209.)
-10,0
0,0 10,0
-10,0
0,0 10,0
Self generated noise in intake DLD/DLDR/DLDY Self generated noise in outlet DLD/DLDR/DLDY
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)A
ir ve
loci
ty(V
eloc
ity o
ver
gros
s cr
oss
sect
ion
area
.)
Air
velo
city
(Vel
ocity
ove
r gr
oss
cros
s se
ctio
n ar
ea.)
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)
Correction for gross cross section area:a × b in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
Correction for gross cross section area:a × b in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
dB(A)
63 Hz
125 Hz250 Hz
500 Hz
1 kHz
2 kHz
4 kHz 8 kHz
1,5
2
3
4
5 6 7 8 9 10
10 m/s
5 m/s
3 m/s
2 m/s
5 m/s
3 m/s
2 m/s
10 m/s
70 dB
60 dB
50 dB
40 dB
30 dB 30 dB
70 dB
60 dB
50 dB
40 dB
dB(A)
63 Hz
125 Hz
250 Hz
500 Hz1 kHz
2 kHz 4 kHz 8 kHz
1,5
2
3
4
5 6 7 8 9 10
Self generated noise number
Self generated noise number
10
9
8
7
6
Outdoor air
Extract air
Supplyair
Exhaust air
OutletRoom
Intake
Out-doors
Fan
Fan IntakeOutlet
7
8
9
10
We reserve the right to make changes without prior notice 223
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Rectangular straight silencer DLDY
l indab | silencers
Width amm
Code Length lmm
Static insertion attenuation / octave band [dB]
Resis-tance
number
Self gen-erated noise
number Intake
Self gen-erated noise
number Outlet63 125 250 500 1000 2000 4000 8000
400 2009 650 2 5 9 18 21 16 13 10 1,0 2,0 1,6
400 2010 650 3 7 11 23 26 20 16 12 2,5 2,7 2,0
400 2009 1250 2 9 16 30 36 27 19 14 1,2 2,0 1,6
400 2010 1250 4 12 21 38 46 34 25 19 2,8 2,7 2,0
400 2009 1850 3 12 24 43 51 38 26 19 1,3 2,0 1,6
400 2010 1850 5 16 31 53 60 49 33 25 3,2 2,7 2,0
500 2012 650 2 5 9 17 17 13 10 8 1,1 2,0 1,7
500 2013 650 3 7 11 20 21 16 13 10 2,2 2,5 2,0
500 2014 650 4 9 14 25 26 20 16 12 4,7 3,3 2,5
500 2012 1250 3 9 16 28 29 22 16 12 1,2 2,0 1,7
500 2013 1250 4 12 20 34 36 27 19 14 2,4 2,5 2,0
500 2014 1250 6 15 26 41 46 34 25 19 5,3 3,3 2,5
500 2012 1850 4 13 24 39 42 31 21 16 1,3 2,0 1,7
500 2013 1850 5 16 30 47 51 38 26 19 2,6 2,5 2,0
500 2014 1850 8 21 38 58 60 49 33 25 5,9 3,3 2,5
600 2012 650 2 6 11 22 28 21 17 13 3,1 3,0 2,0
600 2013 650 2 5 7 13 12 10 8 6 0,6 1,7 1,5
600 2015 650 2 6 9 15 14 11 9 7 1,1 2,0 1,7
600 2016 650 3 7 11 18 17 13 10 8 2,0 2,4 2,0
600 2017 650 4 9 13 22 21 16 13 10 3,8 3,0 2,4
600 2012 1250 3 11 20 36 49 36 26 19 3,8 3,0 2,0
600 2013 1250 2 8 14 22 22 16 12 9 0,7 1,7 1,5
600 2015 1250 3 10 16 25 25 18 13 10 1,2 2,0 1,7
600 2016 1250 4 12 20 30 29 22 16 12 2,2 2,4 2,0
600 2017 1250 6 15 24 36 36 27 19 14 4,1 3,0 2,4
600 2012 1850 4 15 30 50 60 51 35 26 4,4 3,0 2,0
600 2013 1850 3 11 20 30 31 22 15 11 0,7 1,7 1,5
600 2015 1850 4 14 24 36 36 26 18 13 1,3 2,0 1,7
600 2016 1850 6 17 29 42 42 31 21 16 2,4 2,4 2,0
600 2017 1850 8 21 35 50 51 38 26 19 4,5 3,0 2,4
700 2012 650 2 5 9 18 20 15 12 9 1,6 2,3 1,8
700 2013 650 3 8 12 23 28 21 17 13 4,8 3,5 2,3
700 2016 650 3 6 9 14 12 10 8 6 1,1 2,0 1,8
700 2017 650 3 7 10 16 14 11 9 7 1,9 2,3 2,0
700 2012 1250 3 9 17 30 35 26 19 14 1,9 2,3 1,8
700 2013 1250 4 13 23 38 49 36 26 19 5,7 3,5 2,3
700 2016 1250 4 10 16 24 22 16 12 9 1,2 2,0 1,8
700 2017 1250 5 12 19 27 25 18 13 10 2,0 2,3 2,0
700 2012 1850 3 12 24 41 50 36 25 19 2,2 2,3 1,8
700 2013 1850 6 18 34 53 60 51 35 26 6,5 3,5 2,3
700 2016 1850 5 14 24 33 31 22 15 11 1,3 2,0 1,8
700 2017 1850 6 17 28 38 36 26 18 13 2,2 2,3 2,0
800 2016 650 2 6 10 19 20 15 12 9 2,5 2,7 2,0
800 2017 650 4 9 14 24 28 21 17 13 6,9 4,0 2,7
800 2019 650 3 6 9 13 11 9 7 5 1,2 2,0 1,8
800 2016 1250 3 11 19 31 35 26 19 14 2,8 2,7 2,0
800 2017 1250 6 15 26 40 49 36 26 19 8,0 4,0 2,7
800 2019 1250 4 11 16 22 19 14 10 8 1,2 2,0 1,8
800 2016 1850 4 15 28 44 50 36 25 19 3,2 2,7 2,0
800 2017 1850 7 20 37 56 60 51 35 26 9,1 4,0 2,7
800 2019 1850 5 15 24 31 27 19 13 10 1,3 2,0 1,8
800 2016 2450 5 19 36 56 60 47 31 23 3,5 2,7 2,0
800 2017 2450 9 26 49 60 60 60 44 33 10,3 4,0 2,7
800 2019 2450 6 19 31 40 35 24 16 12 1,4 2,0 1,8
900 2015 650 2 4 7 13 13 10 8 6 0,7 1,8 1,5
900 2017 650 2 6 9 15 15 12 10 7 1,5 2,3 1,8
900 2019 650 3 7 11 20 20 15 12 9 3,5 3,0 2,3
900 2020 650 4 10 15 25 28 21 17 13 9,4 4,5 3,0
900 2015 1250 2 7 13 21 22 16 12 9 0,8 1,8 1,5
900 2017 1250 3 9 16 26 27 20 14 11 1,7 2,3 1,8
224 We reserve the right to make changes without prior notice
228 We reserve the right to make changes without prior notice
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Rectangular curved silencer BDLD
l indab | silencers
DescriptionBDLD is a curved rectangular silencer with convensional design with width and height dimensions that doesn´t exceed the present connection dimensions. The silencer can be produced in all normally existing duct dimensions.
DesignBDLD has an external shell of trapezoidal corrugated sheet metal for stabillity and reduced risk of oscillation.BDLD is designed for low pressure drop with baffle combi-nations that attenuate aspecially low frequences well.The type of insulation material is developed to provide good sound properties, low weight and to be cleanable.BDLD meets the requirements of air tightness class C and pressure class 2 according to EN 1507:2006.DLDY is equipped with joining profile type RJFP.
Tools for dimensioning and planningThe software DIMsilencer is recommended for fast choise of silencer or a complete and fast sound calculation of the duct system.The software CADvent offers dimensioning in an environ-ment with 3D-modelling.Computorised planning can be conducted with automatic presentation of niose levels, pressure drop etc.
Dimensions
If alternative material is required, this shall be stated when ordering, e.g. aluminium zinc (AZ185), stainless (2333) and acid-proof steel (2343).
The silencer is also available with the following accessories/ options.
TRA = Non-insulated inspection hatch.TRB = Hatch intended for external insulation.* TRC = Hatch intended for external insulation.*AIA = 50 mm fire protection insulation. Note! a and
b dimensions increase by 100 mm.AIB = 100 mm fire protection insulation. Note! a and
b dimensions increase by 200 mm.AIA+TRB = 50 mm fire protection insulation and the
appropriate cleaning cover. Note! a and b dimensions increase by 100 mm.
AIB+TRC = 100 mm fire protection insulation and the appropriate cleaning cover. Note! a and b dimensions increase by 200 mm..
* Specify insulation thickness when ordering.
b
y
x
a
b
a
Vertical mounting Horizontal mounting
Ordering exampleBDLD 800 × 600 150-150 3015 TRA
ProductWidth height a × bLeg length x, yCodeAccessories
Rectangular curved silencer BDLD
We reserve the right to make changes without prior notice 229
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Rectangular curved silencer BDLD
l indab | silencers
Manual designing for BDLDA number of silencers can be designed manually, for more combinations of silencers and faster calcu-lations use DIMsilencer. Manual method of calculation is shown below:
A Specify connection dimensions and flow-type location of the silencer.
B Specify the sound power level before the silencer.Read the insertion attenuation from the tables on page 6–8.Calculate the sound power level after the silencer irrespective of the air flow (selv generated noise).
Insertion attenuation
C Determine the pressure drop with help of the graph on page 3 and table on page 4.In this case we have straight ducts before and after the silencer.
Pressure drop
D Determine the self generated noise from the silencer at present air flow.Calculate the sound power level after the silencer inclusive the self generated noise.
Self generated noise
Width 800 mmHeigh 1000 mmLeg lengh 150 mmLocation Exhaust air
Sound power level after silencer without self generated noise
69 63 56 47 46 43 35 27
Area 0,8 m² Air flow 400 l/sGraph on page 3, use resistance number, area and air velocity
Air velocity5 m/s
Pressure drop28 Pa
Correction at disturbance according table on page 4 Factor1
Pressure dropafter correction
28 Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 5, use resistance number and air velocity
59 56 49 46 44 40 36 28
Correction for gross cross section area -1 -1 -1 -1 -1 -1 -1 -1Self generated noise 58 55 48 45 43 39 35 27Sound power level after the silencer 69 64 57 49 48 44 38 30(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
Rectangular curved silencer BDLD
230 We reserve the right to make changes without prior notice
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Rectangular curved silencer BDLD
l indab | silencers
The following table can be used for own manual calculations in accordance with the example on the previous page.
number inletSound power level before silencerAttenuation from table page 6–8Sound power level after silencer without self generated noise
Area m² Air flow l/sGraph on page 3, use resistance number, area and air velocity
Air velocity m/s
Pressure drop Pa
Correction at disturbance according table on page 4 Factor Pressure dropafter correction
Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 5, use resistance number and air velocityCorrection for gross cross section areaSelf generated noiseSound power level after the silencer(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
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Rectangular curved silencer BDLD
l indab | silencers
Pressure dropFollow the directions below and the adjoining graph.
Calculate the gross cross section area a × b in m².
Go horizontal in the graph to the present air flow, l/s.
Go up to the resistance number achieved from the tables on page 6–8.
Read the pressue drop over the silencer, at straight duct connection before and after the silencer, (factor 1,0). For other modes of connection see the table for correction on page 4.
Air flow velocity, which is used at the calculation of the self generated noise, can be read here.
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2
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4 5 6 7 8321 910
54
3
2
0,1
0,2
0,3
0,40,5
1
1,5
200
150
10
15
20
30
40
50
60708090
100
1
5
2
3
4
30 20 15 10 8 64 3 2
1,5
1
30000200001500010000600040003000
200015001000
600400300
200150
v [m/s]
Ac
[m²]
Δpt [
Pa]
R
q [l/s]
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Rectangular curved silencer BDLD
l indab | silencers
Pressure dropPresent pressure drop = Read pressure drop × below factorD = The largest connection side (a or b) of the silencer.
The table contains of a selection of the most common disturbance cases.
Distance before the silencer Distance after the silencer
Silencer After the silencer
Factor
[dB]
[dB]
Incr
eam
ent t
o ad
d to
the
high
est d
B-v
alue
3
2
1
00 5 8 10
Difference between dB-values to be added
15 20
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Rectangular curved silencer BDLD
l indab | silencers
Self generated noise per frequence band Decide from the location of the silencer whether it is the supply or exhaust graph that shall be used. (Rule of mem-ory - the side that leads away from the fan, i.e. at supply air the outlet graph is used and at exhaust air the in-take graph.)
Go horizontally into the present graph, at present air ve-locity, to the self generated noise number.
Then go vertically up to the crossing of the different fre-quency band lines.
Read the self generated noise, at gross cross section area 1 m², for each frequency band straight out to the left. In the example only the 8000 Hz-reading is shown.
Add or subtract the correction for the present gross cross section area.
Sound power level after the silencerThe sound power level after the silencer can be calculated for all frequences by a logarithmical addition of:
"The self generated noise" and "The sound power level before the silencer".
The shown example gives at 8000 Hz
Self generated noise = 28 dB - 1 dB = 27dB
Sound power level before the silencer - the attenuation: 44 dB - 17 dB = 27dB
Logarithmic addition of 27 and 27 = 30 dB
(See graph for logarithmical addition on page 4.)
Self generated noise in intake BDLD Self generated noise in outlet BDLD
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)A
ir ve
loci
ty(V
eloc
ity o
ver
gros
s cr
oss
sect
ion
area
.)
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)A
ir ve
loci
ty(V
eloc
ity o
ver
gros
s cr
oss
sect
ion
area
.)
Correction for gross cross section area:B × H in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
Correction for gross cross section area:B × H in m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
-10,0
0,0 10,0
-10, 0
0,0 10, 0
dB(A)
10 m/s
5 m/s
3 m/s
2 m/s
5 m/s
3 m/s
2 m/s
10 m/s
70 dB
60 dB
50 dB
40 dB
30 dB 30 dB
70 dB
60 dB
50 dB
40 dB
dB(A)
63 Hz
125 Hz
250 Hz
500 Hz
1 k Hz
2 k Hz4 k Hz 8 k Hz
1,5
2
3
4
5 6 7 8 9 10
Self generated noise number
63 Hz
125 Hz
250 Hz
500 Hz
1 k Hz
2 k Hz
4 k Hz 8 k Hz
1,5
2
3
4
5 6 7 8 9 10
Self generated noise number
10
9 8
7
6
Outdoor air
Extract air
Supplyair
Exhaust air
OutletRoom
Intake
Out-doors
Fan
Fan IntakeOutlet
7
8
9
10
234 We reserve the right to make changes without prior notice
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Rectangular curved silencer BDLD
l indab | silencers
Width amm Code
Leg length (x+y)/2
mm
Static insertion attenuation / octave band [dB]
Resis-tance
number
Self gener-ated noise
number Intake/Out-
lett63 125 250 500 1000 2000 4000 8000
400 3006 150 1 6 16 17 17 14 13 15 3,3 2,0
400 3009 150 1 7 12 12 13 12 11 12 3,3 2,0
400 3010 150 1 8 14 14 14 13 12 13 7,1 2,7
400 3006 300 1 8 20 23 25 20 17 17 3,6 2,0
400 3009 300 1 8 15 16 17 14 13 13 3,4 2,0
400 3010 300 2 10 18 19 20 16 14 15 7,4 2,7
400 3006 450 1 9 23 29 34 26 21 20 3,8 2,0
400 3009 450 2 10 19 20 22 17 14 14 3,5 2,0
400 3010 450 2 12 22 24 26 20 17 16 7,6 2,7
500 3006 150 1 7 15 15 15 14 13 14 2,0 1,7
500 3007 150 2 8 21 22 20 17 17 19 6,0 2,5
500 3014 150 2 11 15 15 15 14 13 14 12,4 3,3
500 3006 300 1 8 18 19 21 18 16 16 2,1 1,7
500 3007 300 2 10 25 29 31 27 23 23 6,7 2,5
500 3014 300 3 13 20 21 21 18 16 16 12,8 3,3
500 3006 450 2 9 20 24 27 22 18 18 2,2 1,7
500 3007 450 3 12 29 35 42 36 29 27 7,5 2,5
500 3014 450 4 16 25 26 27 22 18 18 13,2 3,3
600 3006 150 2 7 14 14 14 14 14 14 1,5 1,5
600 3007 150 2 9 19 19 18 16 17 18 3,3 2,0
600 3008 150 3 11 26 27 24 20 20 22 9,6 3,0
600 3006 300 2 8 17 17 18 16 15 16 1,5 1,5
600 3007 300 2 10 23 25 27 23 20 21 3,6 2,0
600 3008 300 4 13 30 34 34 29 26 27 11,1 3,0
600 3006 450 2 9 19 21 23 19 17 17 1,6 1,5
600 3007 450 3 12 26 31 36 29 24 23 3,8 2,0
600 3008 450 4 15 34 40 45 39 33 31 12,7 3,0
700 3008 150 3 9 18 18 17 16 16 18 2,3 1,8
700 3011 150 4 12 22 22 20 18 19 20 8,0 2,8
700 3012 150 3 11 17 17 16 16 16 17 5,0 2,3
700 3008 300 3 11 21 22 23 21 19 20 2,4 1,8
700 3011 300 4 14 27 29 31 26 23 24 8,7 2,8
700 3012 300 4 13 21 22 22 20 18 19 5,2 2,3
700 3008 450 3 12 24 27 30 25 22 22 2,5 1,8
700 3011 450 5 16 31 36 41 34 28 27 9,4 2,8
700 3012 450 4 15 25 27 28 24 21 20 5,4 2,3
800 3008 150 3 10 17 17 16 16 17 17 1,8 1,6
800 3009 150 4 11 22 21 19 19 19 21 3,3 2,0
800 3012 150 4 12 20 20 18 18 18 20 4,7 2,3
800 3015 150 6 16 26 26 23 21 22 23 19,2 4,0
800 3008 300 3 11 20 21 21 20 19 19 1,8 1,6
800 3009 300 4 13 25 27 28 25 23 23 3,6 2,0
800 3012 300 4 14 24 26 26 23 22 22 5,0 2,3
800 3015 300 7 19 31 34 33 30 27 28 21,1 4,0
800 3008 450 3 12 23 25 27 23 21 20 1,9 1,6
800 3009 450 4 14 28 33 37 31 27 26 3,8 2,0
800 3012 450 5 16 28 31 33 28 25 24 5,3 2,3
800 3015 450 8 21 37 41 44 40 33 32 22,9 4,0
900 3008 150 3 10 17 16 15 16 17 17 1,5 1,5
900 3010 150 5 13 25 25 22 21 22 23 4,5 2,3
900 3011 150 7 15 30 31 26 23 25 27 9,6 3,0
900 3013 150 5 13 19 18 17 17 18 19 3,3 2,0
900 3008 300 3 11 19 19 20 19 18 19 1,5 1,5
900 3010 300 5 15 29 31 32 29 27 27 5,0 2,3
900 3011 300 7 17 34 38 37 33 31 32 11,1 3,0
900 3013 300 5 14 22 23 23 21 21 21 3,5 2,0
900 3008 450 3 12 22 23 24 22 20 20 1,6 1,5
900 3010 450 6 16 33 38 43 37 31 31 5,5 2,3
900 3011 450 7 19 38 44 47 42 37 36 12,7 3,0
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Rectangular curved silencer BDLD
l indab | silencers
900 3013 450 5 16 26 28 29 25 23 23 3,6 2,0
1000 3009 150 5 12 20 19 18 18 19 20 2,0 1,7
1000 3010 150 6 13 24 23 20 20 21 23 3,3 2,0
1000 3011 150 7 15 28 28 24 23 24 26 6,0 2,5
1000 3014 150 9 18 32 32 27 24 26 29 19,2 4,0
1000 3009 300 5 13 23 23 23 22 22 22 2,1 1,7
1000 3010 300 6 15 27 29 29 27 25 26 3,6 2,0
1000 3011 300 7 16 32 35 35 32 30 30 6,7 2,5
1000 3014 300 10 21 37 39 37 34 32 33 22,0 4,0
1000 3009 450 5 14 25 27 29 26 24 24 2,2 1,7
1000 3010 450 6 16 31 35 38 33 29 28 3,8 2,0
1000 3011 450 7 18 36 41 45 42 36 35 7,5 2,5
1000 3014 450 10 24 42 46 48 43 39 38 24,8 4,0
1200 3010 150 6 13 19 17 17 18 19 20 1,5 1,5
1200 3011 150 7 14 22 21 19 20 21 22 2,1 1,7
1200 3012 150 8 15 26 24 21 22 24 25 3,3 2,0
1200 3014 150 11 18 34 34 28 26 29 31 9,6 3,0
1200 3018 150 12 21 34 34 28 26 29 31 19,2 4,0
1200 3010 300 6 14 21 21 21 21 21 21 1,5 1,5
1200 3011 300 7 15 25 25 25 24 24 24 2,3 1,7
1200 3012 300 8 17 29 30 30 28 27 28 3,6 2,0
1200 3014 300 11 20 38 41 38 36 35 36 11,1 3,0
1200 3018 300 13 24 39 41 38 36 35 36 22,0 4,0
1200 3010 450 6 15 24 24 25 24 23 22 1,6 1,5
1200 3011 450 7 16 28 30 31 29 27 26 2,4 1,7
1200 3012 450 8 18 32 36 39 34 31 31 3,8 2,0
1200 3014 450 11 22 42 47 49 45 41 40 12,7 3,0
1200 3018 450 14 27 44 48 49 45 41 40 24,8 4,0
1400 3012 150 8 15 21 19 18 20 22 22 1,6 1,6
1400 3013 150 9 16 24 22 20 22 23 25 2,3 1,8
1400 3014 150 10 17 27 26 22 23 26 27 3,3 2,0
1400 3015 150 12 19 31 30 25 25 28 30 5,0 2,3
1400 3016 150 13 20 35 34 28 27 30 33 8,0 2,8
1400 3020 150 16 24 36 36 29 28 31 34 19,2 4,0
1400 3022 150 11 20 23 21 19 21 23 24 5,0 2,3
1400 3012 300 8 16 24 23 23 23 23 24 1,7 1,6
1400 3013 300 9 17 27 27 26 26 26 27 2,4 1,8
1400 3014 300 10 19 31 32 31 30 29 30 3,6 2,0
1400 3015 300 12 20 35 36 35 34 33 33 5,5 2,3
1400 3016 300 14 22 39 41 38 37 36 37 9,2 2,8
1400 3020 300 17 27 41 43 39 38 37 38 22,0 4,0
1400 3022 300 11 22 27 26 25 25 25 25 5,2 2,3
1400 3012 450 8 17 26 27 27 26 25 25 1,8 1,6
1400 3013 450 9 19 30 32 33 31 29 29 2,5 1,8
1400 3014 450 10 20 34 38 39 36 33 32 3,8 2,0
1400 3015 450 12 22 39 42 46 42 38 37 6,1 2,3
1400 3016 450 14 24 43 47 49 46 42 41 10,4 2,8
1400 3020 450 17 29 46 50 50 47 44 43 24,8 4,0
1400 3022 450 11 24 31 31 31 29 28 27 5,4 2,3
1600 3013 150 9 16 23 20 19 21 23 24 1,8 1,6
1600 3015 150 11 18 28 26 22 24 26 28 3,3 2,0
1600 3016 150 13 20 31 30 25 26 28 30 4,7 2,3
1600 3017 150 14 21 35 34 27 28 31 33 7,1 2,7
1600 3023 150 10 20 21 19 17 20 22 22 3,3 2,0
1600 3025 150 17 26 33 32 26 27 30 32 19,2 4,0
1600 3013 300 9 17 25 24 24 24 25 25 1,8 1,6
1600 3015 300 12 20 31 32 31 30 30 31 3,6 2,0
1600 3016 300 13 21 35 36 35 34 33 34 5,2 2,3
1600 3017 300 15 23 39 40 38 37 36 37 8,0 2,7
Width amm Code
Leg length (x+y)/2
mm
Static insertion attenuation / octave band [dB]
Resis-tance
number
Self gener-ated noise
number Intake/Out-
lett63 125 250 500 1000 2000 4000 8000
236 We reserve the right to make changes without prior notice
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Rectangular curved silencer BDLD
l indab | silencers
1600 3023 300 11 21 24 23 22 23 23 23 3,4 2,0
1600 3025 300 18 29 39 40 37 36 36 36 21,1 4,0
1600 3013 450 9 18 28 28 29 28 27 27 1,9 1,6
1600 3015 450 12 21 35 38 40 36 34 33 3,8 2,0
1600 3016 450 13 23 39 43 46 42 38 38 5,7 2,3
1600 3017 450 15 25 43 47 49 46 42 42 9,0 2,7
1600 3023 450 11 23 27 27 26 26 25 25 3,5 2,0
1600 3025 450 19 32 45 47 48 46 41 40 22,9 4,0
1800 3014 150 9 16 23 21 19 21 23 24 1,9 1,6
1800 3016 150 11 18 28 26 22 24 26 28 3,3 2,0
1800 3019 150 16 22 37 37 29 29 32 35 9,6 3,0
1800 3026 150 12 21 23 21 19 21 23 24 4,5 2,3
1800 3027 150 14 23 28 26 22 24 26 28 9,6 3,0
1800 3030 150 15 25 27 25 22 23 26 27 11,8 3,3
1800 3014 300 9 17 26 25 25 25 25 26 2,0 1,6
1800 3016 300 12 20 31 32 31 30 30 31 3,6 2,0
1800 3019 300 16 24 41 43 40 38 38 39 11,1 3,0
1800 3026 300 12 23 27 26 24 25 25 26 4,7 2,3
1800 3027 300 15 26 33 33 31 30 30 31 10,1 3,0
1800 3030 300 16 27 32 32 30 29 29 30 12,5 3,3
1800 3014 450 9 19 28 29 30 29 28 27 2,1 1,6
1800 3016 450 12 21 35 38 40 36 34 33 3,8 2,0
1800 3019 450 16 26 46 50 50 48 45 44 12,7 3,0
1800 3026 450 12 24 30 30 30 28 28 27 4,9 2,3
1800 3027 450 16 28 38 40 40 36 34 33 10,7 3,0
1800 3030 450 16 30 37 38 37 35 33 32 13,1 3,3
2000 3016 150 9 17 24 22 19 22 24 24 2,0 1,7
2000 3018 150 11 18 28 26 22 24 26 28 3,3 2,0
2000 3019 150 13 19 30 29 24 25 28 30 4,4 2,2
2000 3020 150 14 20 33 32 26 27 30 32 6,0 2,5
2000 3021 150 15 22 36 36 28 28 32 34 8,4 2,9
2000 3026 150 18 25 37 37 29 29 32 35 19,2 4,0
2000 3029 150 16 24 30 28 24 25 28 29 12,4 3,3
2000 3016 300 9 18 26 26 25 25 26 26 2,1 1,7
2000 3018 300 12 20 31 32 31 30 30 31 3,6 2,0
2000 3019 300 13 21 34 35 35 33 33 33 4,8 2,2
2000 3020 300 14 22 37 39 37 36 36 36 6,7 2,5
2000 3021 300 15 24 40 42 39 38 38 38 9,7 2,9
2000 3026 300 19 28 42 44 40 38 38 39 22,0 4,0
2000 3029 300 16 27 35 36 34 32 32 33 13,3 3,3
2000 3016 450 10 19 29 30 31 29 28 28 2,2 1,7
2000 3018 450 12 21 35 38 40 36 34 33 3,8 2,0
2000 3019 450 13 23 38 42 46 41 37 37 5,3 2,2
2000 3020 450 14 24 41 45 48 46 41 40 7,5 2,5
2000 3021 450 16 25 44 49 50 47 44 43 11,0 2,9
2000 3026 450 19 31 47 51 50 48 45 44 24,8 4,0
2000 3029 450 17 29 41 43 44 40 37 36 14,2 3,3
Width amm Code
Leg length (x+y)/2
mm
Static insertion attenuation / octave band [dB]
Resis-tance
number
Self gener-ated noise
number Intake/Out-
lett63 125 250 500 1000 2000 4000 8000
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Rectangular straight low-built silencer
LRLB
l indab | silencers
DescriptionRectangular silencer with low installation height.
Insulation with surface cover which can be cleaned with a rotating brush.
LRLB meets the requirments of tightness class C and pres-sure class 2 according to EN 1507:2006.
LRLB is equipped with joining profile type RJFP.
Note that the choice of interior fire insulation to reduce the free area of the silencer, leading to higher pressure drop.
Dimensions
If alternative material is required, this shall be stated when ordering, e.g. aluminium zinc (AZ185), stainless (2333) and acid-proof steel (2343).
The silencer is also available with the following accessories/ options.
TRA = Non-insulated inspection hatch.TRB = Hatch intended for external insulation.* AIC = Internal 50 mm fire protection insulation. All
insulation is covered with perforated steel.AIB+TRB = Internal 50 mm fire protection insulation as
above and cleaning outlet for internal insulation.
* Specify insulation thickness when ordering.Ordering example
238 We reserve the right to make changes without prior notice
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Rectangular straight low-built silencer
LRLB
l indab | silencers
Manual designing for LRLBA number of silencers can be designed manually, for more combinations of silencers and faster calcu-lations use DIMsilencer. Manual method of calculation is shown below:
A Specify connection dimensions and flow-type location of the silencer.
B Specify the sound power level before the silencer.Read the insertion attenuation from the table on pages 1.Calculate the sound power level after the silencer irrespective of the air flow (selv generated noise).
Insertion attenuation
C Determine the pressure drop with help of the graph on page 4–5 and table on page 6In this case we have straight ducts before and after the silencer.
Pressure drop
D Determine the self generated noise from the silencer at present air flow.Calculate the sound power level after the silencer inclusive the self generated noise.
Self generated noise
Width 800 mmHeigh 200 mmLeg lengh 950 mmLocation Exhaust air
Sound power level after silencer without self generated noise
67 64 57 43 39 39 37 30
Area 0,16 m² Air flow 600 l/sGraph on page 4–5, use resistance number, area and air velocity
Air velocity3,8 m/s
Pressure drop35 Pa
Correction at disturbance according table on page 6 Factor1
Pressure dropafter correction
35 Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 7, use resistance number and air velocity
52 47 45 42 38 34 30 22
Correction for gross cross section area -9 -9 -9 -9 -9 -9 -9 -9Self generated noise 43 38 36 33 29 25 21 13Sound power level after the silencer 67 64 57 43 39 39 37 30(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
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Rectangular straight low-built silencer
LRLB
l indab | silencers
The following table can be used for own manual calculations in accordance with the example on the previous page.
inletSound power level before silencerAttenuation from table pages 1Sound power level after silencer without self generated noise
Area m² Air flow l/sGraph on page 4–5, use resistance number, area and air velocity
Air velocity m/s
Pressure drop Pa
Correction at disturbance according table on page 6 Factor Pressure dropafter correction
Pa
63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000HzGraph on page 7, use resistance number and air velocityCorrection for gross cross section areaSelf generated noiseSound power level after the silencer(Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise)
240 We reserve the right to make changes without prior notice
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Rectangular straight low-built silencer
LRLB
l indab | silencers
Technical data
Height 150 mm
Height 200 mm
Height 250 mm
10
20
30
40
50
[Pa/m]
100 200 300 500 400
q
Δpt
1000 2000 [l/s]
350×
150
a×b
400×
150
500×
150
600×
150
800×
150
1000
×150
10
20
30
40
50
100 200 300 500 400 1000 2000
250×
200
300×
200
350×
200
400×
200
500×
200
600×
200
800×
200
1000
×200
[l/s]
[Pa/m]
q
Δpt
a×b
10
20
30
40
50
100 200 300 500 400 1000 2000
250×
250
300×
250
350×
250
400×
250
500×
250
600×
250
800×
250
1000
×250
[l/s]
[Pa/m]
q
Δpt
a×b
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Rectangular straight low-built silencer
LRLB
l indab | silencers
Technical data
Height 300 mm
Height 350 mm
Height 400 mm
10
20
30
40
50
100 200 300 500 400 1000 2000
300×
300
350×
300
400×
300
500×
300
600×
300
800×
300
1000
×300
[l/s]
[Pa/m]
q
Δpt
a×b
10
20
30
40
50
100 200 300 500 400 1000 2000
350×
350
400×
350
500×
350
600×
350
800×
350
1000
×350
[l/s]
[Pa/m]
q
Δpt
a×b
10
20
30
40
50
100 200 300 500 400 1000 2000
400×
400
500×
400
600×
400
800×
400
1000
×400
[l/s]
[Pa/m]
q
Δpt
a×b
242 We reserve the right to make changes without prior notice
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16
17
18
Rectangular straight low-built silencer
LRLB
l indab | silencers
Pressure dropPresent pressure drop = Read pressure drop × below factorD = The largest connection side (a or b) of the silencer.
The table contains of a selection of the most common disturbance cases.
Distance before the silencer Distance after the silencer
Silencer After the silencer
Factor
[dB]
[dB]
Incr
eam
ent t
o ad
d to
the
high
est d
B-v
alue
3
2
1
00 5 8 10
Difference between dB-values to be added
15 20
We reserve the right to make changes without prior notice 243
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2
3
4
5
6
7
8
9
10
11
12
13
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18
Rectangular straight low-built silencer
LRLB
l indab | silencers
Self generated noise per frequence band Decide from the location of the silencer whether it is the supply or exhaust graph that shall be used. (Rule of mem-ory - the side that leads away from the fan, i.e. at supply air the outlet graph is used and at exhaust air the in-take graph.)
Go horizontally into the present graph, at present air ve-locity, to the self generated noise number.
Then go vertically up to the crossing of the different fre-quency band lines.
Read the self generated noise, at gross cross section area 1 m², for each frequency band straight out to the left. In the example only the 8000 Hz-reading is shown.
Add or subtract the correction for the present gross cross section area.
Sound power level after the silencerThe sound power level after the silencer can be calculated for all frequences by a logarithmical addition of:
”The self generated noise” and ”The sound power level before the silencer”.
The shown example gives at 8000 Hz
Self generated noise = 28 dB - 1 dB = 27dB
Sound power level before the silencer - the attenuation: 44 dB - 17 dB = 27dB
Logarithmic addition of 27 and 27 = 30 dB
(See graph for logarithmical addition on page 6).
Self generated noise in intake LRLB Self generated noise in outlet LRLB
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)
Air
velo
city
(Vel
ocity
ove
r gr
oss
cros
s se
ctio
n ar
ea.)
Air
velo
city
(Vel
ocity
ove
r gr
oss
cros
s se
ctio
n ar
ea.)
Sel
f gen
erat
ed n
oise
at
gros
s cr
oss
sect
ion
area
1 m
²(C
orre
ctio
n fa
ctor
to
othe
r ar
ea a
ccor
din
g to
ab
ove.
)
Correction for gross cross section area:B × H i m²: 1 2 3 80,1
-100,4
-70,8
-4 -1 0 +3 +610
+9 +100,2
Correction for gross cross section area:B × H i m²: 1 2 3 80,1