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1 Sound attenuator with recessed connection for rectangular ducts GENERAL is, due to its unique design with connection facing the side baffles, is suitable for use both in ducts and in direct connection to the air handling unit. QUICK FACTS Very compact rectangular attenuator Excellent aerodynamic characteristics Very low pressure drop through tapered splitters Environmentally friendly acoustic material, approved by independent test institute: CLEANOLON -AL Washable surface layer CLEANOLON -AL Available with inspection hatch Fire protected version with 50 mm mineral wool also available Connection dimensions from 400 x 300 to 2200 x 2200 Included in the databases Magic CAD and Point Registered design. The company reserves the right to make design changes without prior notice. 1

2 DESIGN is manufactured as standard in galvanized steel sheet. The sound attenuating material, CLEANOLON -AL, is tested to Swedish standard with regard to cleaning, fibreloosening, ageing properties, emissions, washable etc. is supplied as standard with C clip connection to connecting ducts. FUNCTION The low pressure drop in has been achieved by designing the splitter elements entirely according to the basic laws of aerodynamics. In order to further optimize the sound attenuator regarding pressure drop, some of the active components of the attenuator are located outside the connection position. This solution has contributed to increasing the set attenuation. The low pressure drop can be utilized for example to: reduce the space requirements through selecting a smaller attenuator decrease the pressure setting in the fan for the same size of attenuator minimize the inherent sound generation in the system due to lower velocities and reduced pressure setting facilitate adaptation of the attenuator to the connected duct system includes all the positive characteristics that Swegon earlier models have offered. By taking into account properties of the component materials and exploiting aerodynamic flow principles, Swegon has optimized the attenuator with regard to: acoustic properties of the sound attenuating materials. thickness of the splitters. width of the slots. length of the splitters. surface covering. By combining the above factors, Swegon can always offer the best sound attenuation and lowest pressure drop according to customer requirements. MAINTENANCE Under normal conditions is maintenance free. If the attenuator is required to be cleanable, it is possible to order with a factory fitted inspection hatch: see accessories. The inspection hatch reveals all the slots to achieve the best possible accessibility. It may however in many cases be advantageous to locate the inspection hatch in the duct adjoining the sound attenuator. ACCESSORIES T1: T2: T3: T4: Non-insulated inspection hatch. Fire-insulated inspection hatch. The sound attenuators is supplied fire-insulated with 50 mm mineral wool. N.B. The attenuator s H measurement is then increased by 100 mm. Perforated steel sheet covering of the insulation material. LOOSE SPLITTERS can be supplied as loose baffles without any housing. Please contact Swegon for further information. CUSTOMER MODIFICATIONS Besides the accessories and variants illustrated in the catalogue, it is always possible to make modifications. For example, can be ordered with lateral connection and horizontal splitters. Swegon, in consultation with a customer, can optimize the sound attenuator with respect to sound attenuation, size, adaptation to air handling unit and choice of materials (e.g. stainless steel, aluminium/zinc and etc.). For further information, please contact Swegon. PLANNING, GENERAL The TECHNICAL DATA shown here refer to the standard version of. Dampers, duct bends, and other equipment near the sound attenuator will increase the inherent sound generated in the attenuator as well as the pressure drop. The data shown are based on an even airflow in and out of the sound attenuator. See also the section on SYSTEM POWER and PRESSURE DROP. When the splitter surfaces are covered with perforated steel sheet, the inherent sound generated increases. See the section on INHERENT SOUND GENERATION. With a standard connection the total measurement of the sound attenuator is 200 mm more than the B-measurement. For special requirements the sound attenuator can be supplied for connection to its outer housing, in which case the B- measurement will remain the same as the attenuator s total width. See attenuator CADENZA. ENVIRONMENT "Environment declaration" is available on Swegon s website on the Internet or may be ordered from one of our sales offices. INSTALLATION The C-clip on this product are only intended for connection to ducts. The product is to be installed suspended with supports under its entire width. 2

3 PLANNING Dimensions/Sound attenuation 1. Calculate the required sound attenuation manually or with the aid of Swegon sound calculation software ProAc (available on our website). 2. Select the attenuator that can manage the calculated sound attenuation requirements for low frequencies (above all, 125 Hz) under TECHNICAL DATA. Also check the sound attenuation in the higher frequencies. 3. Check the H-measurement for the sound attenuator to optimize the pressure drop, also considering the system power. 4. The p-number obtained from TECHNICAL DATA is used to determine the pressure drop through the attenuator. The higher the p-number, the higher the pressure drop, see Nomogram Check the inherent sound generated in the attenuator. Pressure drop 1. Calculate the gross frontal area B x H (m 2 ). 2. Go to the relevant airflow in Nomogram Follow the line up vertically to the p-number obtained for the selected attenuator under TECHNICAL DATA. 4. Read off the pressure drop for duct-duct installation. 5. On selection of types of installation other than duct-duct, correct the pressure drop value with the aid of Graph 1. The pressure drop in Nomogram 1 is multiplied by the value obtained from Graph 1, depending on the installation of the attenuator. Example: A sound attenuator is located next to the air handling unit in a fan room. The airflow is 4 m 3 /s and the sound attenuator is mounted in a duct with a width of 1800 mm. The sound attenuator 1841 with a p-number of 3.2 has been selected from TECHNICAL DATA. The sound attenuator has a width of 1800 mm and is 600 mm high. The gross frontal area will be 1.08 m 2. Nomogram 1 shows a pressure drop of 26 Pa. If the sound attenuator had instead been duct-chamber mounted, the pressure drop would have been multiplied by 2.2 as in Graph 1. The pressure drop then obtained would have been 57 Pa. Nomogram 1. Determining the pressure drop Graph 1. Correction for other installations Curve 1; Chamber-Duct, Curve 2; Duct-Chamber Curve 3; Chamber-Chamber 3

4 SYSTEM POWER AND PRESSURE DROP Sound attenuator installed before or after a bend The corrections below must be multiplied by those in the graph showing pressure drop. Attenuator before bend: Attenuator after bend: Distance Corr.factor Distance Corr.factor 3xD 1,1 1xD 1,2 2xD 1,2 0 (direct) 1,3 1xD 1,35 0 (direct) 1,5 Sound attenuator installed before or after chamber The total pressure drop through the attenuator is obtained by multiplying the correction factor from Graph 1 by the pressure drop from Nomogram 1. Sound attenuator installed before or after a branch A sound attenuator installed after a branch is comparable to one installed after a chamber. See curve 1 in Graph 1. The total pressure drop through the attenuator is obtained by multiplying the correction factor by the pressure drop from Nomogram 1. Figure 1. Before or after a bend Distance refers to that between the sound attenuator and the bend, D refers to the largest side of the attenuator. Total pressure drop = attenuator pressure drop as in Nomogram 1 x correction factor. A sound attenuator installed before a branch is comparable to one installed before a chamber. See curve 2 in Graph 1. The total pressure drop through the attenuator is obtained by multiplying the correction factor by the pressure drop from Nomogram 1. Sound attenuator installed by an air handling unit It is difficult to obtain accurate corrections for a sound attenuator installed next to an air handling unit. This is mainly due to the variations in the fan outlet size between different manufacturers. The most common arrangement is a relatively small fan outlet (leading to high air velocities) combined with a large duct connection (with airflows of around 4-6 m/s). In general terms, the angle between the fan outlet and duct should not exceed 15. To ensure a good distribution of the airstream, a diffuser plate can be used with favourable results. Sound attenuator installed next to a damper A sound attenuator installed next to a damper can result in large pressure drops. As the damper angle increases there is a corresponding increase in the velocity profile spread. This leads to a greater air velocity between the attenuator splitters and thereby higher pressure drops. Sound attenuators connected in series When sound attenuators are connected in series, the basic principle is to avoid changes in the velocity profile between the connected attenuators. If the straight section between the attenuators can be made sufficiently long (4 x D), then in the best case the stated pressure drop per single attenuator will apply. One important aspect is also to ensure that the splitters in the attenuators do not cover other air slots. Please contact Swegon when connecting attenuators in series. 4

5 INHERENT SOUND GENERATION An attenuator does not only suppress sound, but also generates sound itself when there are high velocities and large pressure drops. There are normally no problems encountered as long as the recommended working range as shown in Nomogram 1 is observed. For accurate calculations there are curves marked in Nomogram 1 for inherent sound. Please use ProAc, in which we show pressure drop in addition to inherent sound levels. The L wt values given are sound power levels for with a reference value of W for an airflow of 1 m 3 /s. By correcting L wt with K 1 for, the sound power level for each octave band is obtained. For with perforated steel sheet covering, first add 12 db to the indicated L wt value and then correct using K 2. Hz K 2K 4K 8K K K Corrections for airflows other than 1 m 3 /s are made by using Graph 2 below. Inherent sound generated must be 8 10 db lower in every octave band than the requirement for sound power level after the attenuator. Graph 2. Correction for other airflows Example: A sound attenuator is installed next to an air handling unit in a fan room. The airflow is 4m 3 /s and the sound attenuator is mounted in a duct with a width of 1800 mm. The sound attenuator 1841 with a p-value of 3.2 has been selected from TECHNICAL DATA. The height of 600 mm gives a gross frontal area of 1.08 m 2. Nomogram 1 gives L wt = 38 db. Correct with K 1 to obtain an octave band breakdown, and for 4 m 3 /s as in Graph 2: Hz K 2K 4K 8K L wt K m 3 /s L w

6 TECHNICAL DATA B-measurement: 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1800, 2000, 2200 H-measurement: 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2200 B- and H-measurements in bold figures marked in yellow are standard. Total installation measurements in H plane: H+40 mm L-measurement: See the table in TECHNICAL DATA. Figure 2. INSPECTION HATCH In certain situations, requirements are placed on the attenuator being cleanable either through a hatch on the attenuator itself or in the duct next to it. The accessory T1 is available for with an inspection hatch that facilitates access to all air slots. The technical data are not affected when the accessory CAL- MO T1 is used. FIRE INSULATION In many cases the attenuator is installed in fire protected duct systems. When ventilation ducts are covered with fire protective insulation of 50 mm mineral wool, the sound attenuator may be externally insulated directly at site or in certain cases at the factory. This is available for as an accessory. There are two options: to only insulate the inspection hatch ( T2) or to insulate the whole attenuator ( T3). Technical data are not affected when accessories T2 or T3 are used. Figure 4. with 50 mm of mineral wool as fire protection Figure 3, with inspection hatch, T1 In those cases when is fitted with an inspection hatch, it is on the upper or lower surface of the attenuator (i.e. the B-measurement is defined as the width). When it is necessary to have the inspection hatch on the side, for example in confined spaces, the B-measurement will then be defined as the height instead (see above diagram). There must be enough space to open the hatch. The distance required for the fully open hatch is 700 mm. 6

7 TECHNICAL DATA B-measurement Code Length Static set attenuation (db) as in ISO 7235:91 P-value (mm) (mm) K 2K 4K 8K

8 TECHNICAL DATA, continued B-measurement Code Length Static set attenuation (db) as in ISO 7235:91 P-value (mm) (mm) K 2K 4K 8K

9 TECHNICAL DATA, continued B-measurement Code Length Static set attenuation (db) as in ISO 7235:91 P-value (mm) (mm) K 2K 4K 8K

10 MEASUREMENTS AND WEIGHTS B-measurement: 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1800, 2000, 2200 H-measurement: 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2200 B- and H-measurements in bold figures marked in yellow are standard: the others may be ordered. Total installation measurements in H plane: H+40 mm L = see the table in TECHNICAL DATA Weight = please contact your nearest Swegon office. SPECIFICATION Product Rectangular sound attenuator a aaaa bbbb x cccc x dddd Version: Code: Measurement: B x H x L Accessories T1 = Non-insulated inspection hatch T2 = Fire protected inspection hatch T3 = Attenuator supplied fire protected with 50 mm mineral wool. T4 = Perforated steel sheet cover N.B. If the attenuator is equipped with an inspection hatch there must be sufficient space to open the hatch. Fully opened, the hatch requires a distance of 700 mm. Figure 5. splitters are designed in accordance with the basic laws of aerodynamics. In addition, some of the active components of the attenuator are located outside the connection position. These improvements have considerably reduced the pressure drop in comparison with conventional attenuators. Order example Straight sound attenuator, code 0631, fulfilling the sound attenuation requirements as calculated. The attenuator is to be fitted with a non-insulated inspection hatch. The installation space is limited vertically to a maximum of 1300 mm, which means that there is sufficient room to open the inspection hatch (700 mm). Order code: a x600x1850 T1 SPECIFICATION EXAMPLE Swegon rectangular sound attenuator, type, with the following functions: Aerodynamically formed splitters give extremely low pressure drop. Insulation material, approved by independent test institute: CLEANOLON -AL. Sound attenuation in db (stated clearly for different frequency bands) Pressure drop in Pa (stated clearly). Size a aaaa bbbb x cccc x dddd xx. units 10