Pipe Network Design Guide.book
Contents
1. 34 Below ceiling applications 20 Beds osse bab oae 37 Bonding 37 Branch 26 Branch max 26 Breaking recommendations 27 C 9 Pipe Network Design Guide Cabinet detection 31 Gables NAYS ntes 20 Cable 20 Cable Tunnels Trays 28 Capillary max length 26 Capillary tube sampling 4 20 28 Choice of detector 28 BULL 28 Clean rooms 20 28 Client parameters 27 Cold 20 28 Cold St re Lait dtr ita cte 32 Computational Fluid Dynamics CFD 27 Computer rooms 28 Concealed sampling pipe 6 Concealed testing applications 20 Contat US ici haeo re aee dae iv Control 20 28 Conventions iii Coverage uses oe e se E IEEE SD 22 Coverage detector max 26 Creating VESDA zones2. 22 Cumulative sample 18 D Detector Min air 2 2 2 7 1 26 Detector choice 28 Detector max 26 Detector specifications 26 20 28 Drop pipe applications 20 39 Pipe Network Design Guide VESDA E 28 environments 20 End 36 Environment 3 Environmental checking 18 Equipment Cubicles 28 Equipment cubicles 20 Exceeding guidelines 27 F Fire zone 24 Fire zone max 5 22 Floor plan pp 2 Floor void sampling 7 Focused protection 31 lici I 32 G Gas 22 37 Good pipe network design 1 Grid overlay 24 Grille 12 H Hangers Choice of
3. 28 High air exchange areas 29 High 6 32 High velocity air 8 Historical buildings 20 28 Hole balance 34 Hole 35 Hole share erect en nes 34 40 Holes and End caps 36 Hospitals oon eee 20 28 Hotels ore rc ac rte Ak 20 28 In Cabinet testing applications 20 In duct applications 20 In cabinet sampling 10 AP COMING c eoe 7 In Ceiling Floor applications 20 In duct sampling 14 Interbeam sampling 6 11 J otio ooo 37 JOIBEIS ott ine esi rn 37 pieceS arcc ordo e o Rei 37 L 20 28 Large area sampling 18 LaserCOMPACT uses 28 LaserFOCUS 28 LaserPLUS uses 28 LaserSCANNER uses 28 Hinc MeL 20 Libraries archival storage 28 Low velocity air 8 M Manufacturing facilities
4. 20 28 Mapping the pipe network 23 Max holes per branch 26 Max response time 22 Maximum aspirating area 22 VESDA Maximum transport time 34 Multi pipe systems 35 MusBHHTis oh oun 20 Museums art galleries 28 N 318 ee cnin 27 O 20 28 On 5 Orienting sample holes 8 P Pa pressure 27 Parameters of detectors 26 Performance based design 27 Pipe Aggregate length 26 BOOS 37 Branch max holes 26 Glue amp 37 OMNIS 37 JOMIS 37 Max branch length pp 26 holes 26 length pp 26 2 26 Multi pipe advantages 35 Performance 36 MSS 37 36 Why use shorter pipes 36 IER IDE IS UENIRE NUS 37 Pipe
5. 37 Pipe network mapping 23 Pipe network testing 33 Plotting sample points 25 Point 22 Pressure air minimum 26 0 8 icis iia di sacs 20 28 Pipe Network Design Guide R Heference 3 Reference checking 18 Reference sampling 18 Refrigerated warehouse 32 Regulations 2 Regulatory parameters 22 Return air Specification pp 12 Return air grille applications 20 Return air grille sampling 12 Return air sampling 8 RPMS 26 RPMs aspirator speed 26 5 Sample hole Max coverage 24 Max 24 Max distance from wall 24 Sample hole coverage 22 Sample hole orientation 8 Sample hole specifications 24 Sample point 22 Sampling hole Max space between 24 Sampling hole her 26 Sampling holes
6. 5 Sample pipe Exhaust pipe Figure 19 Cross section view pipe amp hole setup for large duct For large ducts holes are nominally spaced each 400 mm 16 in Duct No of Hole 0 Nominal pipe flow rate width holes L min cfm 1m 6 3 5 mm 42 2 L min 1 49 cfm 3 ft 4 in 2 i 1 5 m 5 8 3 0 mm 41 4 L min 1 46 cfm ft y in 2m 10 3 0 mm 50 0 L min 1 76 cfm 6 ft 6 in y T Table 2 Hole size for a large duct ASPIRE calculations shown in Tables 1 and 2 apply to a 5 m 16 4 ft inlet pipe and a 2 m 6 56 ft exhaust pipe Always check with local codes and standards for hole size and spacing Condensation from ducts Condensation may occur when the air being sampled is warmer than the air surrounding the detector See the VESDA Pipe Network Installation Guide for information on how to avoid condensation problems 17 Pipe Network Design Guide VESDA Large Area Sampling Areas such as atriums and warehouses with high ceilings require special variations of the pipe network design rules Stratification is a process where due to hot air layers closer to the ceiling smoke loses its thermal energy stops rising and levels out horizontally at a certain height Stratification layers may be formed at different heights restricting the smoke s ability to rise and reach the sampling pipe network
7. 22 2 Time transport 34 TRAINING 2 ZONE COM STRUC 23 42
8. 12 Incd ct Sampling 22 12 14 Condensation from ducts 17 Large Area Sampling eee Deed e e eect e adve Hee e eee 18 Cumulative Sampling pp 18 Reference Sampling ie ede i ecd EG ede Pede EE eee ee ect 18 Third Party Monitoring Equipment te 21 Gas Detection ie 21 Defining the cm 22 Regulatory Requirements 22 Fire and VESDA Addresses e eve dg v 22 Plan and Map a Pipe Network 23 enES TIERS 24 Detector Parameters Rede dedit eee E eee 26 Site Parameters pena ep er UAE nete dine o em d rs HE eden 27 Client Parameters Hip tive ee EE 27 Performance Based Requirements 27 Choice of Detector 28 Designing Pipe Networks for Specific Applications eese 29 Pipe Network Design Guide VESDA Standard ROOMS vanes cian ai eet ees ea PAA ee 29 High Air Exchange Areas 29 Focused Detection
9. de cede 31 High Geiling s c idee deme tete dede eee neo eee deae eue one eae 32 Protecting Two Areas with the Same Pipe pp 33 Testing Design Performance 33 Hole Balance tette edet 34 Maximum Transport 34 Hole Sensitivity 5 35 Advantages of Multi Pipe Systems 12 35 VESDA System Performance Graph 36 Sampling and End Cap Holes Ne 36 Pipe Connections te deiade pede Mate E edo De 37 dle came E 37 Bends mc C Em 37 Tees Y pieces and J Pieces 37 Recording Pipe Network Design Specifications 37 vi VESDA Pipe Network Design Guide 1 1 Scope The Pipe Network Design Guide guide introduces you to the principles of pipe network design While the ASPIRE2 software can help you to design an effective pipe network this guide will cover the principals of good design and aims to assist you in producing the optimum design for a site The Pipe Network Design Guide will help you with the design specifications and management of VESDA laser detection systems 1 2 Introduction to Good Design We recommend you use the following process to design site specifications 1 It is assumed that you already understand the local codes and standards for the site 2 Attending accredited train
10. G6S 2 5V or EC2 5NU VESDA detectors must not be connected or disconnected to a PC while the equipment is powered in an FM Division 2 hazardous classified location defined by FM 3611 FM Approved Applications The product must be powered from VPS 100US 120 VPS 100US 220 or VPS 220 only ONORM F3014 ONORM F3014 transport times for all tubes including capillaries must not exceed 60 seconds from any hole This means that the pre designed pipe networks that include capillaries cannot be used AS1603 8 The performance of this product is dependent upon the configuration of the pipe network Any extensions or modifications to the pipe network may cause the product to stop working correctly You must check that ASPIRE2 approves alterations before making any changes ASPIRE2 is available from your VESDA ASD distributor AS1851 1 2005 Maintenance Standards Wherever this document and the AS1851 1 differ 51851 1 should be followed in preference to this document European Installations The product must use a power supply conforming to EN54 Part 4 Document Number 10193 05 Part Number 30009 VESDA Pipe Network Design Guide Contents SCODO E ce LIU LIU IN ien ata eaters 1 Introduction to Good Design ea 1 Introduction to Pipe Network Design 1 Before YOu Statt aa ebd etn Ead rad edd eng 2 Designing a Pipe Network 2 Gather Site Informat
11. 36 Sampling methods 4 Schools eo ttd 20 28 Sector pressure 26 SEMLIS14 nnt iei Rui 27 Sensitivity 35 Share eme 34 Site layout 2 Site parameters 27 Site BSHEVBy pp 2 41 Pipe Network Design Guide VESDA Software ASPIRE2 33 Transport 22 Specifications of detectors 26 Transport time max 34 Stand off lengths Tunnels scettr in educi 20 High ceilings pp 32 TWO areas iinan nae 33 Standard 29 Storage 20 28 V Stratification 18 Surrounding environment 3 VESDA zone construction 23 System 36 VESDA zones 22 Void sampling 7 T Y JOINS ioi uae 37 Telecommunications 20 28 V OMNES 5 5 ts o ete at 37 Testing software 33 Y BIBCOS a 37 Theatres 21 28 Third party applications
12. A Legend A Ceiling void B Sampling Holes B Figure 5 Ceiling void sampling Legend A Figure 6 Floor void sampling A Floor void B Sampling Holes Pipe Network Design Guide VESDA Return Air Sampling Smoke tends to travel with any mechanically generated air flow Correctly positioning sampling holes in a pipe network across the return air grille of an Air Handling Unit AHU or an exhaust ventilation system ensures that any smoke is detected at the earliest stage Air samples from inside a duct carrying the exhaust air may also be collected see figure 14 Return air sampling over a return air grille on page 13 for details It is recommended that the sampling holes face between 20 and 45 degrees from the direction of the greatest airflow See figure 7 Cross section of pipe position on a return air grille on page 8 Figure 7 Cross section of pipe position a return air grille Hole Orientation Industry experience shows that the pipework can be fine tuned to marginally increase the response time of an aspirating detection system by locating the sampling holes 20 or 45 degrees away from the airflow path Sampling can be improved by avoiding the high and low velocity areas One common problem with this model is that the detector needs to work in all possible situations If you are installing pipework into a high airflow area keep in mind what will happen if when the AHUs are t
13. VESDA Pipe Network Design Guide August 2007 Documen t Number 10193 05 Part Number 30009 xtralis Pipe Network Design Guide VESDA VESDA Pipe Network Design Guide Intellectual Property and Copyright This document includes registered and unregistered trademarks All trademarks displayed are the trademarks of their respective owners Your use of this document does not constitute or create a licence or any other right to use the name and or trademark and or label This document is subject to copyright owned by Xtralis AG Xtralis You agree not to copy communicate to the public adapt distribute transfer sell modify or publish any contents of this document without the express prior written consent of Xtralis Disclaimer The contents of this document is provided on an as is basis No representation or warranty either express or implied is made as to the completeness accuracy or reliability of the contents of this document The manufacturer reserves the right to change designs or specifications without obligation and without further notice Except as otherwise provided all warranties express or implied including without limitation any implied warranties of merchantability and fitness for a particular purpose are expressly excluded General Warning This product must only be installed configured and used strictly in accordance with the General Terms and Conditions User Manual and product documents available
14. 2 2 500 sq ft 8 000 sq ft 20 000 sq ft 20 000 sq ft Maximum 1 1 4 4 number of 2 branches 2 branches 8 branches 8 branches Pipes Maximum 25 m 80 ft 80 m 260 ft 200 m 200 m aggregate 650 ft 650 ft length Maximum N A N A 50m 50m d 160 ft 160 ft pipe Maximum 15 m 50 ft 50 m 164 ft N A N A branch length Maximum 6 20 25 25 sampling holes per pipe including end cap hole Maximum 4 20 Aggregate Aggregate max sampling holes max 25 25 per branch including end cap hole Maximum 4 m 13 ft for 4 m 13 ft for 4 m 13 ft for 4 m 13 ft for length of small bore 5 2 small bore 5 2 small bore small bore 5 2 capillaries mm tube and8 mm tube and 8 5 2 mm tube mm tube and 8 m 26 ft drop m 26 ft drop and 8 m 26 m 26 ft drop pipes pipes ft drop pipes pipes Aspirator Fixed Fixed 3 000 rpm 3 000 rpm speed 4 200 rpm 4 200 rpm minimum maximum Minimum 12 liters minute 20 liters minute 20 liters 20 liters minute system air flow minute Minimum 65 Pa 70 Pa 70 Pa 70 Pa sector pressure Table 4 VESDA laser detector parameters VESDA Pipe Network Design Guide The parameters given above are for a typical pipe network Site conditions and requirements will dictate the final parameters for each site The aggregate pipe length can exceed the published values provided the minimum pressure at each sampling point is at least 25 pascals It is recommended that trans
15. a Class B digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception the user is encouraged to try to correct the interference by one or more of the following measures re orientate or relocate the receiving antenna increase the separation between the equipment and receiver connect the equipment to a power outlet which is on a different power circuit to the receiver or consult the dealer or an experienced radio television technician for help FDA This VESDA product incorporates a laser device and is classified as a Class 1 laser product that complies with FDA regulations 21 CFR 1040 10 The laser is housed in a sealed detector chamber and contains no serviceable parts The laser emits invisible light and can be hazardous if viewed with the naked eye Under no circumstances should the detector chamber be opened FM 3611 Hazardous Approval Warning Exposure to some chemicals may degrade the sealing of relays used on the detector Relays used on the detector are marked TX2 5V
16. for protecting standard rooms High Air Exchange Areas High air exchange areas normally use some form of mechanical ventilation to maintain dust free operations Most local codes and standards support that any environment with 7 5 air exchanges or more is classified as a high air volume exchange area Most local codes and standards also require that the higher the airflow the smaller the area that can be protected by each sample hole At the time of writing this manual the US NFPA 72 for traditional point detectors uses Air changes hour 60 30 20 15 12 10 86 75 7 5 m covered per hole 12 23 35 46 58 70 81 84 84 125 250 375 500 625 750 875 900 Sq covered per hole 900 Figure 28 Point coverage in high air exchange areas Note The US 72 code on spacings in high airflow areas has an exception for air sampling systems such as the VESDA range 29 Pipe Network Design Guide VESDA 30 The sampling methods used for high air movement areas are a combination of return air and on ceiling sampling All fire codes require that the detector spacing is reduce in high airflow environments The return air sampling may be conducted at a return grille or via in duct sampling In high air exchange environments the air flow direction is influenced by artificial means Any air volume outside the direct air flow path may not reach the sampling points on the return gr
17. from Xtralis All proper health and safety precautions must be taken during the installation commissioning and maintenance of the product The system should not be connected to a power source until all the components have been installed Proper safety precautions must be taken during tests and maintenance of the products when these are still connected to the power source Failure to do so or tampering with the electronics inside the products can result in an electric shock causing injury or death and may cause equipment damage Xtralis is not responsible and cannot be held accountable for any liability that may arise due to improper use of the equipment and or failure to take proper precautions Only persons trained through an Xtralis accredited training course can install test and maintain the system Liability You agree to install configure and use the products strictly in accordance with the User Manual and product documents available from Xtralis Xtralis is not liable to you or any other person for incidental indirect or consequential loss expense or damages of any kind including without limitation loss of business loss of profits or loss of data arising out of your use of the products Without limiting this general disclaimer the following specific warnings and disclaimers also apply Fitness for Purpose You agree that you have been provided with a reasonable opportunity to appraise the products and have made your own independent assess
18. longer time than would otherwise be the case Oke diluted by Air High Concentrafion Samples collected Smoke collected closer to the Detector here Air grille 1 Air grille 2 Air grille 3 Air grille 4 Figure 15 Smoke dilution effect over several air sampling points In duct Sampling In a fire event ventilation duct systems can convey smoke usually hot toxic gases and flames from one area to another Duct systems may also supply air to aid combustion in the fire location Therefore the effective management of smoke control such as dampers and shutters to contain smoke spread and fire growth is essential for life safety LaserCOMPACT models VLC 500D and VLC 505D are recommended for duct applications Xtralis has conducted extensive testing in duct environments to determine the optimum installation parameters Key Design Considerations The inlet pipe must be inserted at a distance between six to ten duct widths or diameters from any disturbances to the flow generated by sharp bends plenums nozzles branch connections etc The inlet and exhaust pipes must have the same length They must be sealed at the far end with an end cap The holes on the inlet and exhaust pipes should be facing the airflow as shown in figure 17 Small duct sampling top view on page 15 and 3 Holes with the same orientation eliminate unwanted flow faults associated with cyclical operation maintenance or power failure of the duct system Howeve
19. square and or rectangular plotting may be required Pipe Network Design Guide Legend Square plotting of sampling holes Grid Overlay C Rectangular plotting of sampling holes Figure 26 Square and rectangular plotting of sampling holes After plotting the sampling holes determine the optimum positioning of the VESDA laser detector keeping in mind the good design principals of Shorter multiple pipe runs To find out why this is critical see VESDA System Performance Graph on page 36 Minimum changes in pipe direction Next plot the pipes on to the site plan by joining the holes and terminating these at the detector Legend A VESDA laser detector Sampling pipe 1 Sampling pipe 2 Sampling pipe 3 B C D E Sampling pipe 4 Figure 27 Plotting the sampling pipes by connecting the sampling holes and terminating at the VESDA laser detector 25 Pipe Network Design Guide VESDA Detector Parameters Different detectors in the VESDA range have different characteristics The pipe network design parameters for each of these detectors may vary according to site conditions and requirements 26 The parameters for VESDA laser detectors are given below Suggested LaserFOCUS aserCOMPACT LaserPLUS LaserSCANNER parameters 250 Maximum ate 800 2 000 m 2 000 m covered 2 2 2
20. Factors such as temperature ventilation and roof height all affect the degree of stratification and the level to which the smoke will rise Changes in the above mentioned factors result in different stratification effects on a site Where stratification is likely to occur conventionally designed pipe networks may not be effective Legend A Detail of sampling hole B Stratified smoke layer C Vertical sampling holes Figure 20 Sampling air from areas with high ceilings To overcome the stratification effect a vertical sampling pipe may be installed in addition to the standard pipe on the ceiling The vertical sampling pipe penetrates the stratification layers at different heights and samples the air at multiple levels Cumulative Sampling If you have fans blowing air around inside a protected area any smoke will be dispersed evenly around the area Traditional point detectors will wait until one detector reaches 100 of the smoke threshold before alarming VESDA systems are able to aggregate the detected smoke from all of the sample points and can provide much earlier warning As an example If you have a room with four sampling points and each detects 25 of the allowable smoke level the VESDA systems can aggregate the levels and alarm Cumulative sampling is a significant advantage in high air flow areas Reference Sampling Periodically smoke and other pollutants from external sources may enter a prot
21. Pipe Network Design Guide VESDA 36 VESDA System Performance Graph The VESDA system performance graph illustrates the advantages of using shorter multiple pipes over fewer longer pipe lengths A single pipe of 100 meters has a transport time of 80 seconds Two pipes of 50 meters have a transport time of around 33 seconds Four pipes of 25 meters have a transport time of 20 seconds Each of these configurations will protect the same area but have substantially different transport time performance 130 120 110 100 90 80 70 60 TIME Seconds 50 0 10 20 30 40 50 70 80 90 100 PIPE LENGTH Figure 37 System performance graph Sampling and End Cap Holes The sampling holes are drilled into the pipe s once the pipe network has been installed Endcaps must always be placed at the end of each sampling pipe ASPIRE2 calculations will determine the diameter of each sampling hole and the end cap hole The end cap hole can be used as another sampling hole but is generally used to improve the transport time for the pipe The diameter of the end cap hole is determined by the parameters of the pipe network such as the pipe length and the number of sampling holes VESDA Pipe Network Design Guide Pipe Connections Joints Pipe joints must be airtight Glue together the pipes once the final form of the network has been determined Do NOT glue the pipes to the pipe inlet and exhaust ma
22. ctated by local codes and standards or by installation requirements Typically the maximum distance is likely to be to the corner of the room Note The spacings imposed by your local codes and standards may well be related to the cost of conventional point detectors With a VESDA system it is possible to substantially increase the density of sampling points at negligible cost Grids of 4 m X 4 m 13 ft X 13 ft 6m X 6 m 20 ft X 20 ft or 4m X8 m 13 ft X 26 ft are popular choices Legend A Maximum distance of sampling hole from the wall Max 5 1 m or 16 ft B Spacing between sampling Holes Max 10 2 m or 32 ft oe CE Figure 24 Illustration of plotting sampling holes and spacing between holes VESDA Sampling Hole Conventions The typical maximum size for a fire zone is 2000 20 000 sq ft The maximum area covered by a sample point is 104 1120 sq ft The sample hole will not be more than 5 1 m from walls 16 ft The maximum space between sampling holes is 10 2 meters 33 ft A sample point shall not be more than 7 2 meters 23 ft from any point in the room Oir ROO cos Plot the remaining sampling holes for the row Normally these will be spaced at equal distance from each other Figure 25 Plotting the first row of sampling holes 24 VESDA Plot sampling holes in equidistant parallel rows to form squares If the area to be plotted is irregularly shaped a combination of
23. d not monitor more than one AHU End cap without hole Legend A Sampling pipe Return grill Sampling hole Figure 14 Return air sampling over a return air grille Dilution of return air grille samples Consideration should be given to the number of AHUs protected by a detector Theoretically the number of AHUs monitored is limited only by the maximum length of pipe runs for details see Detector Parameters on page 26 However the nature of air movement and the degree of smoke dilution that can occur in installations of more than three AHUs monitored by one detector can adversely affect the VESDA system response times Banks of AHUs have localizing effects on air movement air in one section of a fire zone tends to circulate between the supply and return ducts of the AHU in that section Air movement at right angles to the main circulation is reduced and smoke generated by a fire occurring in an area covered by one AHU tends to be concentrated within that area 13 14 Pipe Network Design Guide VESDA If smoke concentrations occur at the extreme end of the sample pipe run a smoke laden air sample must pass a number of other sampling points all of which are supplying only slightly polluted samples if they are near the fire source or completely clean samples if they are far away from the fire source The net result is the dilution of the smoke sample leading to a lower reading after a
24. ded includes Site name and address Site use application Site measurements and layout Factors requiring special attention The number and location of Xtralis addresses Grid overlay showing the pipe network layout with sampling hole positions Recommended sampling method s Recommended VESDA detector ASPIRE2 results Recommended alarm thresholds 37 Pipe Network Design Guide 38 VESDA VESDA Index A Above 9 Above Cabinet applications 20 Aggregate pipe length 26 Aggregate smoke detection 18 Air exchange areas 29 Air OW CMT DVD 3 Air flow min 26 Air pressure minimum 26 Air sampling methods 4 36 Aircraft hangars 20 28 Ambient conditions 3 Archival storage 20 Area protected 26 Art galleries 20 Aspirator 26 ASPIRE 2 33 iu pe n 28 eat 20 Stand off lengths pp 32 Auditoria 20 28 B Background checking 18 Balance
25. e 11 Illustration of in cabinet sampling using capillaries amp drop pipes 10 VESDA Note Pipe Network Design Guide Care must be taken when installing sample points on the top of cabinets with extractor fans These fans may create low air pressure in the cabinet which may stop any air samples being able to enter the sampling point Inter beam Sampling Beam pockets are created between large ceiling beams A typical on ceiling air sampling pipe network would normally be mounted below these large areas and may not be able to sample the air between the beams To overcome this a rigid pipe may extend vertically from the sampling pipe upwards into the space between the beams E At the top end the direction of the pipe is changed to horizontal The end of the horizontal sampling pipe is capped with a sealed end cap which may or may not have a sample hole in it C A sampling hole is drilled just before the endcap D Legend A Sampling pipe C Endcap E Vertical sampling pipe B Beam pockets D Sampling hole Figure 12 Inter beam sampling 11 12 Pipe Network Design Guide VESDA Guidelines for return air sampling include 1 Place the sample pipe probe in the path of the greatest airflow More than one sampling hole may be required for large grilles NFPA 76 recommendations specify that each sampling hole can cover a maximum of 0 4 4 sq ft Care should be taken to k
26. e design is to have a relatively equal air flow through all sampling holes To achieve this the Hole Balance should be as close to 100 as possible Pipe length number of sampling holes hole size and endcap hole size all effect the Hole Balance Reducing the number of holes per pipe and using multiple pipes will increase the balance 4 7 4 8 4 9 5 0 5 1 5 2 5 4 5 5 5 7 5 8 6 0 6 2 6 5 Sample point with least air flow Figure 34 Hole balance The mathematical formula is Least Flow Balance x 100 Balance Average Flow x 100 87 Maximum Transport Time Maximum transport time indicates the longest time taken for smoke to travel from a sampling hole to the detector You should aim to get the lowest possible time without compromising on the Hole Balance and the Hole Share values Note Subject to local codes and standards the maximum transport time is 120 seconds We recommend the maximum transport time of less than 60 seconds when early warning is desired VESDA Pipe Network Design Guide Pipe lengths affect the time to transport a sample of air from the collection point to the detector Factors like bends diameter of sampling holes and endcap holes also affect the transport time Figure 36 Illustration showing single and multiple pipe network systems for the same area on page 35 illustrates how the same area can be covered by different pipe lengths Hole Sensitivi
27. ected zone temporarily raising the smoke level In this case the detector will detect the smoke and generate an alarm Referencing is employed to compensate for the periodic rise in smoke levels and to avoid nuisance alarms in high sensitivity areas A separate VESDA detector is used to draw air from the external source and produce a reference reading of the background level of smoke and pollutants The reference reading is then subtracted from all VESDA detectors monitoring the internal VESDA Addresses also known as VESDA Zones This allows the internal VESDA detectors to determine if a rise in smoke levels is due to background pollution or a problem inside the VESDA zone of protection The ability to check the background level of smoke greatly reduces the chance of detectors false alarming VESDA detectors in large installations typically operate at varying sensitivity levels In such instances the level of subtraction can be set differently for each detector 18 VESDA Referencing is configured through VESDA VSC LCD Programmer or VSM Software See the respective manuals for details Pipe Network Design Guide Legend A Internal VESDA detectors Reference area Car park Loading bay etc B Reference VESDA detector C Reference sample pipe VESDAnet Figure 21 Heference sampling 19 Pipe Network Design Guide Different sampling methods for some of the more common app
28. eep the number of bends to a minimum We recommend that sampling holes should be angled at 20 to 45 to the airflow 5 high velocity air flows it is advisable to use standoff fittings to keep the sampling pipes at least 50 mm to 200 mm 2 to 8 in in front of the grille Installing any closer to the grille will put the sample point in an area of negative air pressure 6 The pipe may require capping with an end cap without a hole depending upon the ASPIRE2 software calculations 7 Where maintenance requires the removal of the sampling pipes on a regular basis the pipe network design should provide for use of socket unions to ensure correct orientation of sampling holes on re connection Figure 13 Typical return air sampling application Return Air Grille Sampling The sampling pipe is placed over the return air grille of a duct or an Air Handling Unit AHU Figure 14 Return air sampling over a return air grille on page 13 illustrates pipe mounting over the return air grille to avoid dilution of air samples and possible build up of pressure in the pipe network The number of AHUs that can be covered by different detectors is dependent on the suction power of the AHU and also on the size of the return air grille VESDA Pipe Network Design Guide Generally a LaserPLUS or LaserSCANNER detector should not monitor more than four AHUs a LaserCOMPACT should not monitor more than two and a LaserFOCUS shoul
29. from the sampling pipe and in enclosed areas like cabinets The guidelines for capillary sampling are When possible use capillaries of the same length 2 The maximum capillary tube Internal Diameter ID should be 5 mm 3 8 in 3 Maintain balance within the pipe network by using the ASPIRE2 software to determine the size of the sampling hole required 4 Capillary tubes should not exceed 8 m 26 ft 5 The positioning of the sampling hole for in cabinet sampling is dependant on air flow con ditions In most instances the sampling hole is positioned close to the top of the interior of the cabinet See Figure 11 Illustration of in cabinet sampling using capillaries amp drop pipes on page 10 If you wish to use capillary sizes outside these guidelines then please use the ASPIRE2 software to check that you will still have an acceptable design VESDA Pipe Network Design Guide Open Area Protection On ceiling Sampling Typically the pipe network is suspended approximately 25 mm to 300 mm 1 in to 1 ft below the ceiling in the area to be protected Figure 2 A typical on ceiling installation Pipe Network Design Guide VESDA Concealed Sampling Pipe Network Capillary tube sampling is ideal where the sampling pipe needs to be concealed for aesthetic or security reasons The main pipe network is installed in the ceiling void with capillary tubes branching off at regular intervals to penetrate the ceiling panels or ti
30. houses cold stores computer rooms and other applications may require special consideration Determine the protection level required 1 3 Designing a Pipe Network To design an effective pipe network it is suggested that the following steps are taken The order in which these are completed may differ with each project Gather site information Define VESDA Addresses also known as VESDA Zones Select appropriate sampling method s Select appropriate detector Plan and map a pipe network Calculate design performance using the ASPIRE2 software Record the details of the optimum design 1 4 Gather Site Information As a first step it is essential to gather information about the site to be protected For an existing site this may include a site survey prior to designing a pipe network Most of the information required for an effective pipe network design can be determined by a site visit For sites yet to be constructed or where a site visit is not possible a site plan can be used to aid pipe design The information required through a site survey includes Site layout and measurements Regulatory requirements Air flow within the protected area The ambient conditions within the site The purpose for which the site is to be used Construction of the site beams beam pockets and pipe obstructions Likely influence of the external environment on the protected area Site Layout and Measurements Before designi
31. ications There are three basic air sampling methods as described below Typically a site will use more than one Standard Pipe Sampling These guidelines are used for all pipe network designs In addition guidelines specific to different sampling methods may also apply For details see Designing Pipe Networks for Specific Applications on page 29 1 Parameters and values specified in your local codes and standards have precedence over anything suggested in Xtralis documentation 2 recommend smooth bore pipe with 25 mm OD and SA inch IPS internal diameter The preferred CPVC PVC ABS or UPVC pipe internal diameter is 21 mm 0 874 in 3 Maintain at least 500 mm 20 inches of straight pipe before the pipe terminates at the detector 4 Use bend or elbow connectors to change the direction of the pipe Bends maintain better airflow than elbows 5 All sampling pipes should be fitted with an endcap Use the ASPIRE2 software to assist in determining the size of the hole in the endcap 6 For optimum detector performance you should keep pipe runs to a similar length 7 Foroptimum detector performance you should keep a similar number of holes in each pipe 8 Itis better to use multiple pipes of shorter total length than a single pipe of longer length A simple grid layout can be used to suit most rectangular spaces See Grid Overlay on page 24 Capillary Tube Sampling Capillary tubes are used to sample air some distance away
32. ills Below ceiling sampling is used to sample air from areas that fall outside the direct air flow path created by air handling units Figure 29 In ceiling and return air sampling for rooms with high air exchange on page 30 illustrates the use of return air sampling in combination with on ceiling air sampling in areas of high air exchange Figure 29 In ceiling and return air sampling for rooms with high air exchange VESDA Pipe Network Design Guide Focused Detection There are instances where a specific objects within a room requires special monitoring In cabinet sampling uses capillaries to sample air from inside cabinets which are used for electrical IT or other mission critical purposes The capillaries are suspended from a sampling pipe at the top of the equipment cabinet or come up from an under floor void B Legend A Capillary B Drop pipe C Floor void capillary Figure 30 In cabinet air sampling with capillaries drop pipes and under floor sampling methods When installing in cabinet sampling from under the floor the capillary will still always be suspended inside the top of the cabinet Figure 31 Above cabinet sampling 31 32 Pipe Network Design Guide VESDA High Ceiling VESDA Addresses also known as VESDA Zones with high ceilings require special consideration because of the stratification effect To overcome the stratification effect one or more vertical p
33. ing will greatly assist you to produce an optimum site design 3 Gather information about the site This guide will assist you to do this correctly 4 Use the ASPIRE2 software to test and optimize the design Exceeding the guidelines listed in this manual is allowable if the ASPIRE2 software confirms the design Introduction to Pipe Network Design The VESDA early warning aspirating smoke detection system collects air samples through sampling holes on a network of pipes The airflow within a protected area carries the air samples to the sampling holes Conventional smoke detectors wait for the smoke to migrate through the detector The VESDA system actively draws air samples into the sampling pipes These samples are transported through the pipe network to the VESDA detector Legend A End Cap with hole C Detail showing airflow entering a sampling hole E VESDA detector B Air samples D Air sampling pipe Figure 1 A VESDA air sampling system Pipe Network Design Guide VESDA Before You Start To design an efficient pipe network you will need to Have knowledge of your local codes and standards Undergo accredited training in pipe network design and the ASPIRE2 software Have access to a floor plan for the protected area The floor plan must include details of existing or proposed fixtures fittings and equipment Have information about the purpose of the area to be protected Ware
34. ion 2 Site Layout and Measurements 2 Regulatory Requirements 2 S 3 Ambient Conditions 1 2 o terre Pe ee ern mapu pars 3 Purpose of the Site ove aa ce Le Leu Pag dore accede 3 Site GOMSUUCTION Peer ED 3 Surrounding Environment sisisi irinin eiii nennen nennen rennen nnn nns entren nnns 3 Air Sampling Methods edo na en cuan 4 Standard Pipe Sampling 4 Capillary Tube Sampling 5 dec e redeo dee Dans 4 Protection 5 On ceiling Sampling 22 2 a esd deeded 5 Concealed Sampling Pipe Network 2 6 Inter beam Sampling it Beale 6 Return Area Protectlom recece rt d Fg REED Ire eh eR Ev Eden 7 In ceiling or Floor Void Sampling 7 Return Ait Sampling dee i bag 8 ES 8 Object Protectio eia cde iei ere id eee 9 Above Cabinet Sampling pp 9 Inscabinet Samipling us cre i eR 10 Inter beam Sampling 2 2 ccn ce eg gae ee dp ge e oe ee oce 11 Return Air Grille Sampling
35. ipes are installed in addition to the pipes on the ceiling Refer to Large Area Sampling on page 18 for an example of pipe network installation for areas with high ceilings Roof Height m 1 2 3 4 5 6 7 8 9 Distance from roof mm 30 30 30 100 200 300 400 500 600 As the height of the roof increases you will need a larger distance between the roof and the sampling point to continue correctly sampling the air Heights up to 3 m 9 ft can use standard 25 mm 1 in standoffs Legend A Pipe held off roof B Sealed entry to freezer C Normal pipe installation Figure 32 Freezer warehouse installation For further information on designing refrigerated storage see the VESDA Warehouse and Hefrigerated Storage Design Guides VESDA Pipe Network Design Guide Protecting Two Areas with the Same Pipe D B B C Legend A Detector B B Smoky machinery C Sampling point D Protected cabinet E Door LONE A Figure 33 Protecting two environments with one pipe detector This diagram above shows a detector A being used to protected a dirty workshop area B with fumes Detection for this area needs to allow for the presence of workers who smoke The detector is also providing focussed detection for the electrical cabinet D at the back of the room To be able to
36. les A B Legend Tee adaptor C TE B Sampling pipe D C Reducing connector D Capillary tube E Miniature sampling point Figure Detail of concealed sampling pipe network with conical point fittings Inter beam Sampling Beam pockets are created between large ceiling beams A typical on ceiling air sampling pipe network would normally be mounted below these large areas and may not be able to sample the air between the beams To overcome this a rigid pipe may extend vertically from the sampling pipe upwards into the space between the beams E At the top end the direction of the pipe is changed to horizontal The end of the horizontal sampling pipe is capped with a sealed end cap which may or may not have a sample hole in it C A sampling hole is drilled just before the endcap D Legend A Sampling pipe End cap E Vertical sampling pipe B Beam pockets D Sampling hole Figure 4 Inter beam sampling VESDA Pipe Network Design Guide Return Area Protection In ceiling or Floor Void Sampling Some applications use ceiling and under floor voids as return air plenums ducts The pipe network is designed to monitor the air flowing through the return air plenums In ceiling or floor void sampling is also used to monitor any cabling and equipment that may be installed in the ceiling and floor voids
37. lications VESDA Standard Sampling Capillary Sampling Return Air 7 S Q 2 Aircraft hangars e Atria e e Auditoria E e Cable tunnels trays e e Casinos E Clean rooms e e e Cold rooms e e Computer Server rooms e e e e Control rooms amp e Dormitories 7 e e EDP environments 9 e e e e Elec switching cabinets e e e Equipment cubicles e e Historical buildings e Hospitals e e Hotels e Laboratories e e Libraries archival storage amp e e Manufacturing facilities e e Museums art galleries e e Offices e Prisons e e Schools e e Storage facilities amp Telecommunications e e e Substations e e e e e e 20 VESDA Pipe Network Design Guide Standard Sampling Capillary Sampling Return Air 5 gt gt 9 5 E 5 2 9 5 2 c 3 5 D 2 0 2 o 75 2 5 o e e 3 d Theatres e e e e Transportation e Table 3 Sampling methods for different applications Third Party Monitoring Equipment In many environments you will need to not only protect against fire but also protect employees against dangerous environments Gas Detection For occupational health and safety reasons there is a need to monitor fo
38. ment of equipment requiring special protection object detection Location of mechanical ventilators air handling units return air ducts and supply and exhaust air systems The beam layout beam pockets and other odd construction spaces Surrounding Environment Attention should be paid to the environment surrounding the site If the site is situated in an area of high pollution levels the VESDA zone s subjected to frequent exposure to external environment may record unexpected increase in the background level of smoke To compensate for this reference detectors may be required Typically certain areas within the site like warehouses and loading bay areas are normally subject to external environmental influences and require special attention during the design of the pipe network See Figure 21 Heference sampling on page 19 for further information Pipe Network Design Guide VESDA 1 5 Air Sampling Methods Site requirements and conditions determine the best sampling method Local codes and standards may have a bearing on the selection of sampling methods used Air from a VESDA Address Zone is drawn through sampling holes in the pipe network The pipe network transports the sampled air to the detector The position and spacing of sampling holes is dependent upon the pipe network design Refer to table 3 Sampling methods for different applications on page 21 for examples of sampling methods that can be used for various appl
39. ment of the fitness or suitability of the products for your purpose You acknowledge that you have not relied on any oral or written information representation or advice given by or on behalf of Xtralis or its representatives Total Liability To the fullest extent permitted by law that any limitation or exclusion cannot apply the total liability of Xtralis in relation to the products is limited to i in the case of services the cost of having the services supplied again or ii in the case of goods the lowest cost of replacing the goods acquiring equivalent goods or having the goods repaired Indemnification You agree to fully indemnify and hold Xtralis harmless for any claim cost demand or damage including legal costs on a full indemnity basis incurred or which may be incurred arising from your use of the products Miscellaneous If any provision outlined above is found to be invalid or unenforceable by a court of law such invalidity or unenforceability will not affect the remainder which will continue full force and effect All rights not expressly granted are reserved Document Conventions The following typographic conventions are used in this document Convention Description Bold Used to denote emphasis Used for names of menus menu options toolbar buttons Italics Used to denote references to other parts of this document or other documents Used for the result of an action The following ic
40. ms Control Rooms Dormitories EDP Environments Elect Switching Cabinets Equipment Cubicles Historical Buildings Hospitals Hotels Laboratories Libraries Archival Storage Manufacturing Facilities Museums Art Galleries Offices Prisons Schools Storage Areas Substations e Telecommunications e Theatres 28 VesDA Pipe Network Design Guide Detector LaserPLUS LaserSCANNER LaserCOMPACT LaserFOCUS Transportation e e Table 5 Detectors suggested for different applications 1 9 Designing Pipe Networks for Specific Applications VESDA laser systems can be fine tuned to most environments Each environment presents its own special requirements and these are addressed during pipe network design Table 3 Sampling methods for different applications on page 21 suggests air sampling methods normally used for different types of applications A combination of different sampling methods may be used to create the optimum protection for a site Four basic applications are discussed below Protecting standard rooms Protecting high air movement areas Focus detection High ceiling areas Standard Rooms The typical standard room pipe network is an on ceiling sampling method as described in Designing a Pipe Network on page 2 This figure illustrates the on ceiling sampling method employed
41. ng can commence a good knowledge of the site layout is necessary A plan showing measurements of the area to be protected assists with the planning of fire zones and VESDA Addresses also known as VESDA Zones The site layout also shows areas designated for different uses and obstacles to free flow of air partitions air curtains etc Areas requiring special protection and the location of plant machinery equipment cabinet layout and the rack layout in warehouses must be identified on the site plan Regulatory Requirements The designer determines the local codes and standards that apply to the site These need to be considered when creating fire zones VESDA Addresses also known as VESDA Zones and the pipe network design VESDA Pipe Network Design Guide Note Local codes and standards have precedence over any VESDA recommendations Where the parameters set by a VESDA product are not the same as those set by the local codes and standards the local codes and standards should be adopted Air Flow While designing a pipe network you will need to determine the natural airflows in the area to be protected Allowances should be made for any existing or proposed mechanical ventilation systems air curtains roller doors or partitions that are likely to influence the free flow of air If possible conduct smoke tests to determine the air flow The stability or fluctuation in air flow conditions need to be designed into an effective pipe ne
42. nifolds of the detector The use of excessive amounts of glue can block or partially block pipe airflow to the detector and severely affect the detectors ability to detect smoke Testing must be conducted after the pipes are glued together Bends We recommend bends and elbows are used to change the direction of the pipe Wide radius bends are preferred to elbows Good pipe network designs keep the number of bends and elbows to a minimum as they interfere with the optimum airflow We recommend you used multiple pipes instead of bends and elbows Figure 36 Illustration showing single and multiple pipe network systems for the same area on page 35 illustrates the advantage of multiple pipes over bends and elbows Tees Y pieces and J Pieces Tees Y pieces and J pieces are used to branch the trunk pipe line These may also be used for connecting capillary tubes and drop pipes Note Y pieces and J pieces must NOT be branched towards the detector Branching against the natural airflow will disrupt the flow of air in the pipe and lead to unpredictable results SK X To detector To detector Figure 38 Correct placement of Y pieces and J pieces 1 12 Recording Pipe Network Design Specifications Keeping an accurate record of the pipe network design specifications assists the installation engineer to correctly configure the pipe network This information is also useful to complete the commissioning form Information that needs to be recor
43. of the protected area Identify any forced air ventilation and air flows fans air conditioners etc Take into account any customer specifications Determine if the design needs to address Return air grille sampling use of ceiling and under floor voids A Consideration for high ceilings and stratification effect Any requirement for focused detection The pipe network grid is mapped on to the construction drawings The objective of mapping the pipe network is to determine the placement of sampling holes and to optimize the location of the VESDA detector with a view to minimizing the pipe length While mapping the pipe network care should be taken to minimize the number of bends and elbows used We recommended that multiple pipes are used in preference to changes in pipe direction Refer to Figure 36 Illustration showing single and multiple pipe network systems for the same area on page 35 23 Pipe Network Design Guide VESDA Grid Overlay The Grid Overlay method is utilized to map the pipe layout and determine the position of sampling holes The dimensions of the grid depend upon the required maximum or minimum sampling point separations and the required distance of sampling holes from the walls Ideally the aim should be a square grid however the measurements and the shape of the area to be covered will determine the grid Plot the first sampling hole in a manner that it does not exceed the maximum spacing as di
44. ons are used in this document Convention Description Caution This icon is used to indicate that there is a danger to equipment The danger could be loss of data physical damage or permanent corruption of configuration details Warning This icon is used to indicate that there is a danger of electric shock This may lead to death or permanent injury Pipe Network Design Guide VESDA Warning This icon is used to indicate that there is a danger of inhaling dangerous substances This may lead to death or permanent injury Contact Us The Americas 1 781 740 2223 Asia 852 2297 2438 Australia and New Zealand 61 3 9936 7000 Continental Europe 41 55 285 99 99 UK and the Middle East 44 1442 242 330 www xtralis com Codes and Standards Information for Air Sampling Smoke Detection We strongly recommend that this document is read in conjunction with the appropriate local codes and standards for smoke detection and electrical connections This document contains generic product information and some sections may not comply with all local codes and standards In these cases the local codes and standards must take precedence The information below was correct at time of printing but may now be out of date check with your local codes standards and listings for the current restrictions FCC Compliance Statement This equipment has been tested and found to comply with the limits for
45. port time for the network is maintained at 60 seconds or less and hole balance and hole share be at least 70 use ASPIRE2 to calculate these values These values may be relaxed subject to local fire codes and conditions Exceeding the guidelines listed in this manual is allowable if the ASPIRE2 software approves the design Site Parameters Each site presents its own unique set of parameters which the pipe network must meet Some factors likely to influence pipe network design are Level of protection required The area to be covered The environmental conditions The layout of plant machinery equipment or furniture Airflows External influences Special equipment to be protected See Focused Detection on page 31 Combustibility of material construction and stored Client Parameters The client may specify certain requirements to be included into the design These may typically relate to protection of certain equipment or the threshold levels for alarms The pipe network design should incorporate such specifications subject to regulatory and detector parameters Performance Based Requirements Performance based design provides an alternate fire protection system to prescriptive fire codes They do this by assessing the environmental risks at the concept design stage This design approach offers significant advantages The most important is the ability to provide early detection of a fire event It is recommended tha
46. protect these two environments with a single detector you may be able to put a very small hole 2 mm in the middle of the room C and put a very large hole for the sample point inside the cabinet This configuration may generate a Minimum Hole Flow error in ASPIRE2 You will need to fine tune the hole sizes to find a configuration that is acceptable to ASPIRE2 1 10 Testing Design Performance You can test the design performance with the ASPIRE2 software provided by Xtralis The software is used to evaluate the performance differences that occur by making changes to the pipe design For the latest version of the software see www vesda com or contact your local Xtralis office 33 Pipe Network Design Guide VESDA 34 The efficient performance of a pipe network design is dependent upon ASPIRE2 generating acceptable values for Hole 96 balance Maximum transport time Hole sensitivity Factors influencing these values are Pipe length Number of sampling holes Size of the endcap hole Number and radius of bends Number of pipes Length of capillary tubes Size of sampling holes Aspirator speed Hole Balance Hole balance is the amount of air being drawn from the sampling hole with the least amount of air flow divided by the average air flow through the other sampling holes Note Subject to local codes and standards a minimum hole balance of 7096 or greater is recommended The aim of an optimum pip
47. r in some industrial applications where the quality of air inside the duct is poor it is recommended to face all holes on the inlet and exhaust pipes downstream i e 180 to incoming airflow The pipes should always be supported at the duct walls by using fittings such as a rubber grommet Silicon must be used to ensure an airtight seal Make sure that the sampling hole at either end is at least 50 mm 2 in from the duct walls The exhaust pipe must have 4 x 210 mm s in holes The holes should be concentrated in the middle of the duct s width and spaced accordingly VESDA Pipe Network Design Guide Small Duct Width 1 m 3 ft Figure 16 Small duct sampling side view on page 15 shows a side view of a duct section with the insertion positions for the inlet and exhaust pipes The inlet pipe is to be installed in the middle of the duct height H or diameter The exhaust pipe should be inserted approximately 0 5 m 1 64 ft further downstream at a quarter of the height of duct Legend B A Exhaust pipe B Inlet pipe C O mec c C Air flow A 500 20 Figure 16 Small duct sampling side view The details of the number and size of the holes to be used can be found in table 1 Hole size for a small duct on page 16 Legend Holes with same orientation Rubber Grommet Air flow Figure 17 Small duct sampling
48. r dangerous gases in many environments An example is the testing for the presence of the refrigeration gas ammonia in cold storage facilities It is possible to utilize the VESDA air sampling technology by incorporating other off the shelf products to detect the presence of these gases in a protected environment This turnkey solution provides many benefits including cost effectiveness ease of maintenance and management The diagram below illustrates how to sample air coming out of the exhaust port to measure ammonia level using a NH sensor supplied by Drager Polytron Refer to manufacturer s specifications and installation requirements for system integration and performance details 21 Pipe Network Design Guide VESDA A Legend A Air intake probe B VESDA detector C Third party equipment D Air exhaust probe Figure 22 Third party gas detection equipment Note Xtralis does not accept any responsibility for the use of third party gas detection products and presents this concept as an option only Use at designer s discretion 1 6 Defining the Site 22 Regulatory Requirements Local codes and standards determine the maximum spacing between pipes and sampling holes These maximums may change depending on the environment being protected Local codes and standards for aspirating smoke detectors will have precedence over any parameters suggested by Xtralis Some of the key requirements are lis
49. t smoke testing or Computational Fluid Dynamics CFD modelling be performed This method of airflow simulation is used to determine the optimal location for the VESDA detection system by accurately identifying smoke travel from previously acknowledged risks In areas where performance based design is not recognized its concepts may still be adhered to by incorporating the design basics from prescriptive codes i e NFPA 318 and SEMI s14 2000 and the basics outlined in this guide The arrangement of process tools and equipment will alter the airflow dynamics air speed and air direction in the facility To ensure that the system design is effective it is recommended that performance tests are conducted during the completion stage of the site construction 27 Pipe Network Design Guide VESDA 1 8 Choice of Detector The appropriate VESDA detector must be identified once site conditions are known and the sampling method has been selected The detector should be selected based upon area coverage and the type of sampling method selected The table below identifies the suggested VESDA laser detector for different environments Actual site conditions and pipe network design will determine the final choice of the detector Detector LaserPLUS LaserSCANNER LaserCOMPACT LaserFOCUS OR Aircraft Hangars Atria Auditorium Cable Tunnels Trays Casinos Clean Rooms Cold Rooms Computer Roo
50. ted below Maximum permissible transport time Maximum area for afire zone Area of coverage sample hole point detector Maximum spacing between sampling points Maximum area for aspirating systems Fire and VESDA Addresses Fire zones are created to meet regulatory requirements whereas VESDA Addresses also known as VESDA Zones are areas that can be monitored by one VESDA detector VESDA addresses are created for the system to operate within defined parameters for optimum smoke detection VESDA Pipe Network Design Guide Site conditions have an impact in defining VESDA Addresses Some key guidelines need to be observed when creating an Address One detector can monitor only one VESDA Address The VESDA Addresses must comply with the local codes and standards The environmental conditions within each VESDA address should be the same For example the level of pollution and ambient air pressure within each VESDA Address should not change The appropriate VESDA laser detector parameters are met Legend A Asingle physical fire zone C CPUs and storage sub systems E Power supply Two VESDA Addresses D Modems printers and multiplexers F Media storage Figure 23 Constructing VESDA Addresses 1 7 Plan and Map a Pipe Network In planning a pipe network you must Have an understanding of the area to be protected Understand the environmental conditions
51. top view 15 Pipe Network Design Guide 16 For small ducts holes are nominally spaced each 200 mm 8 in Duct No of Hole Nominal pipe flow rate width holes L min cfm 300mm 2 6 mm 39 0 L min 1 4 cfm 12 in m ha 500 mm 5mm 40 7 L min 1 4 cfm 20 in 13 64 in 700 mm 4 4 mm 35 6 L min 1 26 cfm 28 in 5 32 900 mm 5 4 42 8 L min 1 51 cfm 36 in 5 32 Table 1 Hole size for a small duct Large Ducts Width 1 2 m 3 7 ft For large ducts the inlet pipe is recommended to have two branches Figure 19 Cross section view of pipe amp hole setup for large duct on page 17 shows a side view of a duct section with the relative insertion positions for the inlet and exhaust pipes Both inlet branches enter at a quarter of the height of the duct from the top and bottom where H is the height of the duct VESDA The exhaust pipe should be inserted approximately 0 5 m 1 64 ft further downstream in the middle of the height of the duct Legend A Duct flow Exhaust pipe H 2 B Inlet pipe H 4 D 500 mm 20 in Figure 18 Large duct sampling side view VESDA Pipe Network Design Guide The diagram below shows a cross section view of a duct with the locations of the inlet branches and exhaust pipe A recommendation of hole size and spacing arrangement is shown in table 2 Hole size for a large duct on page 17
52. twork design The correct interpretation of air flows impacts on the ability of a pipe network to detect at the earliest stages of a fire Ambient Conditions Where possible the ambient conditions existing within the different areas of a site should be identified It is likely that conditions within a site will differ from one area to the next The efficiency of the VESDA aspirating smoke detection system is dependent upon the accurate determination of the ambient conditions of the monitored area Purpose of the Site The purpose of the site as well as the protected area need to be considered when designing a pipe network Typically a site may comprise of an office area a warehouse a factory a computer room and a cafeteria each requiring special consideration when designing a pipe network Certain manufacturing and processing areas may produce smoke dust steam flame or heat Allowances need to be made for these conditions in the Pipe Network Design Guide Site Construction The designer should consider The material used in the construction of the site It is easier to run pipes through plaster than concrete walls The internal design and the material used for internal surfaces decoration and furniture The types of rooms or areas to be monitored high ceilings high air exchange rate The existence and use of ceiling and floor voids beams and beam pockets Obstructions to pipe layout or the free movement of air Place
53. ty The relative sample hole sensitivity is a measure of the sample hole in relation to the detector s fire threshold sensitivity Mathematically it is presented as Detector Sensitivity Sample hole flow Sum of all sample point flows 96 obs m obs ft 4 7 4 8 4 9 5 0 5 1 5 2 5 4 5 5 5 7 5 8 6 0 6 2 6 5 Sample point Detector sensitivity 0 1 E 2 096 Obs m Sample point flow 0 05 Figure 35 Hole sensitivity 1 11 Advantages of Multi Pipe Systems Subject to the maximum length parameters for the detector it is possible to design a pipe network covering an entire zone with one pipe However for improved pipe network efficiency we strongly recommend you use shorter multiple pipes 1 Pipe 2 Pipes 4 Pipes 100 m 328 ft 50 m 164 ft each 25 m 82 ft each Figure 36 Illustration showing single and multiple pipe network systems for the same area The advantages of multiple pipe systems are Shorter pipes have better response times as the air transport distance from the end of pipe to the detector is reduced See Maximum Transport Time on page 34 for details Shorter pipes have less sampling holes per pipe and can have smaller endcap holes This creates better hole share and hole balance See Hole Balance on page 34 Shorter pipe lengths are likely to have fewer bends resulting in shorter transport times and better air flow System balance multiple pipes provide better system balance 35
54. urned off Legend A Low velocity high static pressure area B High velocity low static pressure area C Airflow Streamlines Figure 8 Sample hole orientation VESDA Pipe Network Design Guide Object Protection Above Cabinet Sampling The sampling pipe is installed directly over the cabinets to be protected Sampling holes are placed over the cabinet ventilation grille The holes are drilled so that they face into the air stream from the cabinet Each monitored cabinet must have at least one sampling hole The exhaust fan can cause sampling problems due to the high airflow around the sample pipe Figure 9 Exhaust grille sampling on a bank of cabinets Pipe Network Design Guide VESDA Legend A Sampling hole Air grill Figure 10 Cabinet sampling for convection cooled cabinet In cabinet Sampling Capillary tubes are used for enclosed in cabinet sampling A flexible capillary tube of a maximum length of 8 m 26 ft is connected to the main pipe network using tee connection with reducing adaptors A variation to the capillary sampling system uses a drop pipe A 12 5 mm 0 5 inch ID rigid pipe is connected to the sampling pipe via a tee connection A C F A Legend A Retainer clips C Equipment cabinets E Rigid drop pipe Sampling hole D Capillary tube F Underfloor void Figur
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