DIMsilencer - Lindab · 2014. 9. 18. · 12. The selected silencer will now appear in our list. There we can see all the technical data. If we highlight the silencer we can now also

DIMsilencer Manual

2

Foreword........................................................................................................................................................ 3

Open DIMsilencer .......................................................................................................................................... 4

Lw: Search silencer ....................................................................................................................................... 4

Enter known information and search ................................................................................................ 4

Search silencer .............................................................................................................................................. 8

Enter known information and search ................................................................................................ 8

Silencer performance .................................................................................................................................. 12

Enter Lw and select silencer .......................................................................................................... 12

Calculation for premises .............................................................................................................................. 15

Insert distribution box .............................................................................................................................. 19

Circular / Rectangular ..................................................................................................................... 20

Circular / Rectangular ..................................................................................................................... 21

Applies to all products .................................................................................................................... 22

Create component ....................................................................................................................................... 22

Applies to all components .............................................................................................................. 23

Analyse how much noise there is ................................................................................................... 23

DIMsilencer help .......................................................................................................................................... 26

Formulas ...................................................................................................................................................... 29

Sound pressure in room ................................................................................................................. 29

DIMsilencer: Damping with one device at distance r, the remainder in the reverberation field ..... 29

Damping with one device at distance r........................................................................................... 29

Damping in direct field (Free field damping)................................................................................... 29

Damping in the reverberation field ................................................................................................. 29

Damping from all noise sources at relevant distances ................................................................... 29

3

Foreword

This manual describes how DIMsilencer is used as a separate program for searching for silencers or as a noise calculation program through an installation.

Each calculation is also linked to a description of the project and its conditions, responsible designer and client.

The manual presents step-by-step how the calculation procedure is intended to be carried out.

The forms and technical documentation that have been used are presented at the back of this manual.

DIMsilencer has four different functions that are divided between four separate main buttons.

The first three buttons are used to search for silencers that satisfy various requirements or comparisons between these properties. The fourth and last button, “Calculation for premises”, calculates from the fan up to and including the premises with the various components involved, apart from straight ducts and bends. These and other components can be created and added as static components.

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Open DIMsilencer

DIMsilencer’s main window with the four function buttons; under the File tab we can choose to open previous calculations or searches.

Before we start any of the calculations, we should place the correct units on the flows and select the relevant unit for noise level. This is done under settings.

Lw: Search silencer

Enter known information and search

1. Press the Lw: Search silencer button.

2. Indicate where the silencer is to be situated, in inlet air / outlet air and before or after the fan. The location can affect the noise data. (If we point to the fan, we can add saved fan data.)

3. Enter noise before the silencer, divided into frequency bands. We can also enter text here describing where we are in the installation.

4. Check the box if the stipulated noise requirements after the silencer are to be divided into frequency bands. If not only enter weighted requirements. If you forget to enter Lw after the silencer, it remains on 0, and when you perform the search a message will appear indicating that no silencers satisfied the requirement.)

5. Then enter the intended air flow and maximum pressure drop in the silencer. Pressure drop 0 functions as all pressure drops. The duct speed changes in line with the changing dimensions of the silencer.

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6. On the right-hand side we select duct type and whether the silencer is to be straight or bent.

7. Enter the size of the silencer.

8. Enter the lengths of X and Y; the minimum length is 100 mm. With straight silencers, the selected length can also be locked. Otherwise all lengths that satisfy the stipulated requirement will be displayed. Standard lengths are 650, 1250, 1850, 2450, and for cleanable +100 mm.

Tip! Look at the speed in the silencer when the dimension is entered, as mistakes are often found here. For example the flow may be incorrect or the dimension of the duct may be too small. This leads to high self-generated emissions in the silencer.

9. When everything looks good, press search. DIMsilencer can now occasionally indicate that there are no silencers that satisfy the stipulated requirements.

Yes, displays potential silencers. No, goes back to ascertain what was entered incorrectly. Most common is the requirement Lw after silencer. Occasionally there are quite simply none that satisfy the requirement. It is then necessary to create a solution using several silencers.

10. Select YES The search results show different values in the various frequency bands. What is to be displayed can be selected in the scroll list in the top right corner. Lw after, damping or self-generated emissions. DIMsilencer shows the selected silencer’s technical data in the lower part. Here it is also possible to choose to view dimensional diagrams or pictures.

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11. When the silencer that is to be used has been found, press the “add to list” button at the bottom right. We can also choose to go back to change the size of the silencer.

12. The selected silencer will now appear in our list. There we can see all the technical data. If we highlight the silencer we can now also name it with the relevant designation, e.g. LD11. If our first search did not manage to damp all the noise, the excess noise is used as the input for a new silencer search.

13. Press new silencer.

14. Now continue as before, steps 4-10.

15. Set the requirement Lw after silencer

16. Air flow

17. Select type of duct connection

18. Select type of silencer

19. Enter size

20. Press search silencer

21. Select from the list of hits for silencers and add to the list.

Example I have chosen to add a rectangular one with a round connection (LRCA-400-500).

22. Our list of silencers now includes two units, which together satisfy the requirement. It is possible here to remove silencers to perform new searches. If we are satisfied, it is time to save the calculation and then print it. We want to enter project data for the printout.

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Project information

1. Before printing, we can enter project information by pressing

2. Enter all the information that is applicable to the project. The information remains in place for the next calculation.

Note! Save the calculation.

Print

1. Press print. DIMsilencer now collects in all the technical data for the selected silencers in the list.

2. In print preview we can zoom in and out on the document.

3. In order to change the printer to which the printout is to be sent, press the printer button

4. Then press select printer, select from the list of available printers and press OK.

5. Now that the correct printer is selected, press OK.

Tip! The printout can be saved as a PDF file. Opt to save the printout and change the file format to PDF.

8

Search silencer

Enter known information and search

1. Press the Search silencer button.

2. Indicate where the silencer is to be situated, in inlet air / outlet air and before or after the fan. The location can affect the noise data.

3. Enter damping that is to be satisfied divided into frequency bands.

4. Enter maximum noise generation so that the silencer does not generate more noise than the duct after the silencer. The default value is 99.

5. Then enter the intended air flow and maximum pressure drop in the silencer. Pressure drop 0 searches on all pressure drops. The duct speed changes in line with the changing dimensions of the silencer.

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6. On the right-hand side we select duct type and whether the silencer is to be straight or bent.

7. Enter the size of the silencer.

8. Enter the lengths of X and Y; the minimum length is 100 mm. With straight silencers, the selected length can also be locked. Otherwise all lengths that satisfy the stipulated requirement will be displayed. Standard lengths are 650, 1250, 1850, 2450, and for cleanable +100 mm.

9. When everything looks good, press search. DIMsilencer can now occasionally indicate that there are no silencers that satisfy the stipulated requirements. Yes, displays potential silencers. No, goes back to ascertain what was entered incorrectly. A common mistake is that the requirement for damping is too great. And occasionally there are quite simply none that satisfy the requirement. It is then necessary to create a solution using several silencers.

10. Press Yes The search results show different values in the various frequency bands. What is to be displayed can be selected in the scroll list in the top right corner, damping or self-generated emissions. DIMsilencer shows the selected silencer’s technical data in the lower part. Here it is also possible to choose to view dimensional diagrams or pictures. Values that do not satisfy the requirement are coloured red here to make it easier for us to see which frequency band does not satisfy the search.

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11. When the silencer that is to be used has been found, press the “add to list” button at the bottom right. The selected silencer will now appear in our list. There we can see all the technical data. If we highlight the silencer we can now also name it with the relevant designation, e.g. LD11. We can now add more silencers with different properties to the list, where we can then select which one is to be used. To perform a new search

12. Press new silencer.


14. Set the desired damping, maximum generation

15. Air flow, pressure drop



18. Enter size

19. Press search silencer

20. Select from the list of hits for silencers and add to the list.

21. Our list of silencers now includes two units, which together satisfy the requirement. It is now possible to remove silencers to perform new searches. If we are satisfied, it is time to save the calculation and then print it.

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Project information




Print



3. In order to change the printer to which the printout is to be sent, press the printer button



Tip! The printout can be saved as a PDF file. Select to save the printout and change the file format to PDF

12

Silencer performance

Enter Lw and select silencer

1. Press the Silencer performance button.

2. Indicate where the silencer is to be situated, in inlet air / outlet air and before or after the fan. The location can affect the noise data.

3. Enter noise before the silencer, divided into frequency bands. We can also enter text describing where we are in the installation. In the columns to the right, the following are presented for the silencer in question: damping, generation Lw after silencer Weighted sound pressure leve

4. Then enter the intended air flow. The duct speed and pressure drop change in line with the changing dimensions of the silencer.

When unreasonable values are entered, the text turns red. Continue until the correct value is entered and the red text has disappeared.

5. On the right-hand side we select duct type.

6. Type of silencer, straight or bent.

7. All the available silencers are now in the scroll list. Point to the desired type.

8. Select size. Look at the speed, which changes constantly depending on the dimension.

9. Then select length.

10. Select type of (codes for various) baffle combinations; only applies to rectangular silencers. To the right of the requirement, all the information about the relevant silencer’s performance is now displayed.

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Tip! Use the up and down arrows to search for the best silencer by size or type.

11. When the right silencer has been found, press “add to list” The selected silencer will now appear in our list. There we can see all the technical data. If we highlight the silencer we can now also name it with the relevant designation, e.g. LD11. We can now add more silencers with different properties to the list, where we can then select which one is to be used. We can also edit the silencer or delete it. To search for or edit silencers.


13. Air flow



16. Enter size

17. Select code, see which one produces the best results.

18. Add to the list.

19. When the search is complete and if we are satisfied, it is time to save the calculation and then print it.

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Project information




Print



3. In order to change the printer to which the printout is to be sent, press the printer button.



Tip! The printout can be saved as a PDF file. Select to save the printout and change the file format to PDF.

15

Calculation for premises

General explanations

Calculation for premises is intended as a powerful tool when the user does not calculate sound in his CAD model. The calculation is from the fan up to and including the premises, where we take into consideration room damping, number of noise sources and noise from both the inlet and outlet air systems. However, we do no include the noise that moves from room to room. Three stages must take place in the correct order: inserting premises, device and fan. DIMsilencer switches off all other selections until these are introduced. We must have such a good knowledge of the installation that we can estimate the flow in the various branches running from the fan out to the premises.

The calculation is built up so that several similar premises can be calculated by saving the calculation and replacing those components that are different. We can also change the premises’ properties and noise requirements.

The upper part of the window presents the current sound pressure level and the stipulated requirements. The central part contains windows for all the inlet/outlet air’s calculated components.

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Specify premises data

1. Start by entering premises name. Length, width and height.

2. Then enter the premises’ sound pressure requirement, Lp

3. Select the type of room damping in the list. When the type has been selected, the relevant alpha value and room damping R value will be presented.

4. Specify how many inlet/outlet air devices and other noise sources (e.g. rotary coolers) there are in the premises.

5. Select whether damping is to be calculated automatically or entered manually. When the value is entered manually, the value is calculated directly. During calculation, consideration is given to distance for direct fields.

6. Enter the location of the devices and the distance r that determines whether the first device is in the direct field or in the reverberation field. See the graph for the relevant premises.

7. When everything is ready, we press add to list. One set of premises now appears in both windows in the top centre, one for inlet air and one for outlet air. In the compilation at the top, we can see the current noise level in the room, the noise requirement divided between two noise sources and the number of devices

When the distance to the first device is short, the sound is not affected by room damping; DIMsilencer calculates D (damping) from the location of the first device in the direct field and then calculates other devices located in the reverberation field.

Special: In order to set individual reverberation times, check off the box to specify reverberation times in frequency bands. Premises type is now switched off and reverberation times for the premises become visible. Here we can now change specific frequencies in order to adapt to our particular premises.

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Insert device

1. We are now going to insert noise sources in the premises. We point to the premises in the inlet air and right-click or point to insert component.

2. The list now only contains devices and other noise sources to choose from. Select insert device. The lower section now changes, instead displaying a structure with devices and a folder with own devices. In order to place own devices, see create own components later.

3. Select Devices and current flow with a pressure

drop.

4. When everything looks good, press “add to list”.

5. Now point instead to the premises in the outlet air window and repeat steps 1-4. DIMsilencer detects that we are now searching outlet air and only displays outlet air devices.

Read off self-generated emissions and determine whether the device meets room requirements. It is possible to make a rough estimate here to check whether the device is too small. The devices will jointly make up the total flow. Each device must carry its own flow. DIMsilencer assumes that it is the same Lw in both devices.

Insert another noise source

1. Highlight the premises and choose to insert components. The list now only contains devices and other noise sources. If we have inserted devices, devices are switched off. Choose to insert another noise source.

2. Enter Name and data and press OK.

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Insert fan

1. Highlight the inlet air device in the window and choose to insert component (we can choose to right-click or point to the insert component button).

2. Then choose to insert fan. All the fans that have been created are displayed at the bottom left. In order to create your own fan, select an existing fan and change it. In order to save without inserting the fan, press save (this is used when several fans are to be created).

3. In order to create and insert a fan, modify the data and press “add to list”. The fan is now saved in the list of fans, at the same time as being added to the list. The fan that is created contains data for pressure side and suction side, which means that we can use it for both inlet air and outlet air.

4. Highlight the outlet air device and choose to insert component.

5. Choose insert fan. All the fans now appear. Enter the suction side’s noise.

6. Select fan and press “add to list”.

In order to create a separate folder, select only Lindab in the left-hand window and enter the name of the new folder to the right. Then create the article including all the data and press save or add to the list.

In order to alter data about a fan, select the relevant fan, modify the data and press “add to list”. DS now asks if we want to replace the fan that is selected in the list. Answer Yes. The new fan will now also appear in the fan list.

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Insert distribution box

1. Highlight the inlet air device in the window and choose to insert component (we can choose to right-click or point to the insert component button).

2. Enter data for the size of the box. The area is displayed!

3. Select now whether the main connection is in one of the ends (2) or in one of the sides (4).

4. Then select whether the main connection is a circular or rectangular duct. Enter the dimensions.

5. Select whether there is an internal baffle, and if it has a double surface.

6. Select how the baffle is installed.

7. Enter width and height.

8. Select type of internal insulation in the scroll list.

9. If an individual value is selected, enter the values for each frequency.

10. Press add to list.

11. If we are going to insert a box in outlet air, select the outlet air fan and repeat steps 1-10.

If the ducts are in contact with each other, e.g. end to end, this is counted as an internally insulated duct, and a baffle should be installed.

In order to change the name of the products, select the product in the calculation list and replace the name in the product window.

In order to modify data, select the product and change the data, then press add to list. DS will ask if we want to replace the selected product. Answer Yes.

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Insert T-piece, X-pipe

Circular / Rectangular

1. Highlight the product after which the T-piece is to be located, choose to insert component (we can choose to right-click or point to the insert component button)

2. Then choose to insert T-piece.

3. Select circular or regular.

4. Select the way in which the noise goes in the calculation, using the button in the next picture

5. Enter dimensions.

6. Enter the flows (used to calculate self-generated noise emissions)

7. Add to the list Inserting several T-pieces Repeat steps 1-7. If we are standing on a T-piece, we will now be asked if we want to replace the selected T-piece. If we answer Yes, the selected T-piece will be changed to the new values that have been entered. If we answer No, another T-piece will be added to the list

In order to change the name of a T-piece, select the T-piece in the product list in the calculation and alter the designation in the window above.

If we want to remove a component from the product list, highlight the product and choose to remove it. We can remove all products apart from premises, devices and fans. We can only change the data for these. These three components are required in order to calculate premises.

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Insert damper

Circular / Rectangular

1. Highlight the product after which the damper is to be located, choose to insert component (we can choose to right-click or point to the insert component button).

2. Then choose to insert damper.

3. Choose from the list of circular dampers or own dampers.

4. Enter flow and press (if own dampers are selected, the flow and pressure are already entered and can only be read).

5. Add to the list.

Emissions from circular dampers are calculated according to flow and pressure.

Rectangular dampers are available in all different dimensions. These must be created for a specific flow and pressure manually. They are then selected under own dampers. Read about how these are created below.

To change the name of a damper, select the inserted damper in the project list and alter the designation in the window above.

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Insert own component

Applies to all products

1. Highlight the product after which the component is to be located, choose to insert own component (we can choose to right-click or point to the insert component button)

2. Then choose to insert own component

3. Select from the list of own components.

4. Add to the list.

Create component

1. Select the folder where own component is to be located

2. Enter product name, flow and pressure (designation can only be entered after the product has been added to the list). All data that is entered is static and will be read on insertion.

3. In order to create more products at the same time, use the save button.

Lw before and Lw after are reported when the product is in the project list and when you are studying the calculation process after insertion.

To change the name of own component, select the inserted component in the project list and alter the designation in the window above.

Inserting several own components. Repeat steps 1-4.

If we are standing on an own component, we will be asked whether we want to replace the selected component.

If we answer Yes, the product will be changed to the selected product.

If we answer No, another product will be added to the list.

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Remove component from calculation

Applies to all components

1. Select the component that is to be deleted.

2. Choose to delete the component (we can choose to right-click or point to the insert component button)

Noise analysis

Analyse how much noise there is

1. The analysis takes place in the top left corner. DIMsilencer reports how much noise there is in the premises and the requirements stipulated for the premises, divided between inlet and outlet air.

2. To the right can be seen how many noise sources we have specified (that we are including).

3. Below in the calculation list can be seen how much noise there is in Lw (noise output level) after each component. Here we can now determine where we are going to place the silencer. Start by looking at all the components that generate noise. Then determine whether fan noise or component noise is the dimensioning factor; it is often a mixture of the two. For this reason, a silencer is required in both places.

4. We can now try positioning a silencer and immediately taking a reading of the sound pressure in the premises at the top left of the screen. When we choose between silencers, the alteration is displayed immediately. When a suitable silencer is selected, we add it to the list.

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Search silencer

1. Indicate where in the calculation we should place the silencer.

2. Choose to search for the silencer (we can choose to right-click or point to the search silencer button)

3. DIMsilencer now enters the relevant noise output level in the field for Lw before. We can enter our own descriptive text for the component before the silencer. Then select the type and dimensions of the silencer. Help is immediately given here to see the speed in the connecting duct (high speed = high self-generated emissions)

4. Then press Search silencer. DIMsilencer tries to find a silencer that will dampen so that the premises’ noise requirements are satisfied. There is often too much noise to manage this with one silencer. In this case DIMsilencer gives a warning that we will not find a single silencer that meets the stipulated requirement.

5. Press Yes.

6. Move the selection box so that the premises’ results can be seen. We can now read off the sound pressure for the premises. When we choose between the silencers, the alteration is displayed immediately.

When the premises’ total sound pressure is satisfied, the total figure also changes from red to green.

7. When a suitable silencer is selected, we add it to the list.

8. Continue by placing out the next silencer. Follow steps 1-7 in order finally to achieve a sound pressure level that satisfies the premises’ requirements. The red figure will then turn black. The distribution between sound requirements for inlet air and outlet air can be shifted by checking the distribution requirement box.

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Save calculation

When the calculation is ready for the first premises, save the calculation as premises 1 (own name). The calculation is now given a name (see at the top of the screen). In order to calculate for the next premises, save with the new name premises 2 (own name) Remove those parts that do not apply to the new calculation and add the new components. If the premises are of a new type, also change the premises and the premises’ requirements.

1. Select Save as under the File tab.

2. Give the calculation the same name as that of the premises.

Retrieve saved calculation

To continue from a previous calculation.

1. Select Retrieve calculation from the File tab.

Print


2. In print preview we can zoom in and out on the document

3. In order to change the printer to which the printout is to be sent, press the printer button.

4. Then press select printer, select from the list of available printers and press OK


Tip! The printout can be saved as a PDF file. Select to save the printout and change the file format to PDF

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DIMsilencer help

Calculating sound pressure

Results for room Inlet air [dB] Outlet air [dB]

Sound output (one noise source

Lw (1) + number of noise sources

32 4 x 6

35 2 x 3

Sound output from all noise sources

Lw all - Damping

38 4

38 4

Sound pressure in room Lp 34 34

Total sound pressure Lp_tot 37

Damping of sound from one device at distance r

The maximum damping, room damping R, is achieved in the reverberation field. As you move nearer to the device, the damping is reduced.

The diagram shows a room with R = 4 dB.

1 = Q factor (location in the room)

2

4

8

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DIMsilencer calculates the resulting damping on the basis of

• 1 device at distance r

• the remainder in the reverberation field

Example Three devices, see diagram. Device 1: damping = 1 dB Device 2: damping = 4 dB Device 3: damping = 4 dB Resulting damping = 3 dB (see formulas)


2

4

8

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Damping in direct sound fields

Damping is dependent on the location of the noise source.

Alignment factor as specified below.

The damping increases 6 dB when the distance is doubled.

Example: Damping of roof device with 1 m distance, approximately = 8 dB


2

4

8

Damping in the reverberation field

Also known as room damping and is independent of distance from the noise source.

Absorption area A is obtained from:

1. The room’s surfaces and absorption factor

2. The room’s reverberation time and volume.

Example: Damping with an absorption area of 10m² Sabine = 4 dB

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Formulas

Sound pressure in room

DnLwLp )log(*10)1(

NB. The same sound output from all the noise sources is assumed

Lp: Lw(1): n: D:

Sound pressure in room Sound output from one device Number of devices Damping

[dB] [dB] [ - ] [dB]

DIMsilencer: Damping with one device at distance r, the remainder in the reverberation field

Ar

q

nLogD

4

4

110

2

q: r: A n:

Alignment factor Distance to device Absorption area Number of devices

[ - ] [m] [m² Sabine] [ - ]

Damping with one device at distance r

Ar

qLogD

4

410)1(

2

or

10

)1(

10

)1(

101010)1(

EF

LogD

q: r: A: F: R:

Alignment factor Distance to device Absorption area Free field damping Room damping

[ - ] [m] [m² Sabine] [dB] [dB]

Damping in direct field (Free field damping)

2410

r

qLogF

(Direct noise dominant)

q: r

Alignment factor Distance to device

[ - ] [m]

Damping in the reverberation field

ALogRD

410

SA (Reflected noise dominant)

A

VT 16,0 (Sabine’s Formula)

A: S: a: V:

Absorption area restriction surface Absorption factor Volume

[m² Sabine] [m²] [ - ] [m³]

Damping from all noise sources at relevant distances

)log(10...101010)()2()1(

101010 nLogDnDDD

D(n): n:

Damping device n Number of devices

[dB] [m]

Documents

DIMsilencer - Lindab · 2014. 9. 18. · 12. The selected silencer will now appear in our list. There we can see all the technical data. If we highlight the silencer we can now also