Smoke and heat control systems - Part 3: Specification for powered smoke and heat exhaust ventilators

This European standard specifies requirements and gives methods for testing powered smoke and heat exhaust ventilators that are intended to be installed as part of a powered smoke and heat exhaust ventilation system. It also provides a procedure for approving a range of powered smoke and heat exhaust ventilators and their motors, from a limited number of tests.

Rauch- und Wärmefreihaltung - Teil 3: Bestimmungen für maschinelle Rauch- und Wärmeabzugsgeräte

Dieser Teil von EN 12101 legt Anforderungen fest und beschreibt Prüfverfahren und das Zulassungsprogramm für eine Baureihe von Abzugsgeräten oder Motoren aufgrund einer Typprüfung für maschinelle Rauch- und Wärmeabzugsgeräte und ihre Motoren, die zum Installieren als Teil einer maschinellen Rauch- und Wärmeabzugsanlage nach prEN 12101-4 und prEN 12101-5 für Bauwerke vorgesehen sind, um im Falle eines Brandes Rauch und Wärme abzuführen. Die Norm prEN 12101-4 gibt die Normen für Bauteile, wie z.B. Kanäle, Klappen und Stromversorgungseinrichtungen, an.

Systemes pour le contrôle des fumées et de la chaleur - Partie 3: Spécifications pour les ventilateurs extracteurs de fumées et de chaleur

La présente Norme européenne spécifie les exigences et donne les méthodes d'essais pour des ventilateurs extracteurs de fumées et de chaleur qui sont destinés a etre installés comme composants dans un systeme de ventilation mécanique pour l'extraction de fumées et de chaleur. Il est également donné une procédure d'approbation d'une gamme de ventilateurs extracteurs de fumées et de chaleur ainsi que leurs moteurs a partir d'un nombre limité d'essais.

Sistemi za nadzor dima in toplote - 3. del: Specifikacije za električne ventilatorje za odvod dima in toplote

General Information

Status
Withdrawn
Publication Date
31-May-2002
Withdrawal Date
18-Oct-2015
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
16-Oct-2015
Due Date
08-Nov-2015
Completion Date
19-Oct-2015

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Smoke and heat control systems - Part 3: Specification for powered smoke and heat exhaust ventilatorsSystemes pour le contrôle des fumées et de la chaleur - Partie 3: Spécifications pour les ventilateurs extracteurs de fumées et de chaleurRauch- und Wärmefreihaltung - Teil 3: Bestimmungen für maschinelle Rauch- und WärmeabzugsgeräteTa slovenski standard je istoveten z:EN 12101-3:2002SIST EN 12101-3:2002en23.12013.220.20ICS:SLOVENSKI

STANDARDSIST EN 12101-3:200201-junij-2002

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12101-3February 2002ICS 13.220.20; 23.120English versionSmoke and heat control systems - Part 3: Specification forpowered smoke and heat exhaust ventilatorsSystèmes pour le contrôle des fumées et de la chaleur -Partie 3: Spécifications pour les ventilateurs extracteurs defumées et de chaleurRauch- und Wärmefreihaltung - Teil 3: Bestimmungen fürmaschinelle Rauch- und WärmeabzugsgeräteThis European Standard was approved by CEN on 9 June 2001.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36

B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12101-3:2002 E

EN 12101-3:2002 (E)2ContentspageForeword3Introduction41 Scope62 Normative references63 Terms and definitions74 Design requirements115 General testing procedures116 Performance requirements and classification127 Marking158 Evaluation of conformity15Annex A

(normative)
Type approval schedule for a range of ventilators17Annex B
(normative)
Type approval schedule for a product range of motors25Annex C
(normative)
Test method for performance of powered ventilators at hightemperature26Annex D
(normative)

Test method for resistance to temperature of electric motorsfor use in powered ventilators32Annex E

(normative)
Test method for operation under load36Annex ZA
(informative)

Clauses of this European Standard addressing essentialrequirements or other provisions of EU Directives38Bibliography42

EN 12101-3:2002 (E)3ForewordThis European Standard has been prepared by Technical Committee CEN/TC 191 "Fixed firefightingsystems", the secretariat of which is held by BSI.This European Standard shall be given the status of a national standard, either by publication of anidentical text or by endorsement, at the latest by August 2002, and conflicting national standards shallbe withdrawn at the latest by November 2003.This European Standard has been prepared under a mandate given to CEN by the EuropeanCommission and the European Free Trade Association, and supports essential requirements of EUDirective 89/106/EEC.For relationship with EU Directive(s), see informative annex ZA, which is an integral part of thisstandard.This European Standard is one of six parts of the European Standard prEN 12101 covering smoke andheat control systems.This European Standard has the general title Smoke and heat control systems and consists of thefollowing six parts:Part 1: Specification for smoke barriers — Requirements and test methodsPart 2: Specification for natural smoke and heat exhaust ventilatorsPart 3: Specification for powered smoke and heat exhaust ventilatorsPart 4: Natural smoke and heat exhaust ventilation systems — Installation and test methodsPart 5: Design and calculation for smoke and exhaust ventilation systems (published as CR 12101-5)Part 6: Design and calculation methods and installation procedure for pressure differential smokecontrol systemsprEN 12101 is included in a series of European Standards planned to cover also:- Gas extinguishing systems (EN 12094 and ISO 14520-1)- Sprinkler systems (EN 12259)- Powder systems (EN 12416)- Explosion protection systems (EN 26184)- Foam systems (EN 13565)- Hose systems (EN 671)- Water spray systemsThe annexes A to E are normative.According to the CEN/CENELEC Internal Regulations, the national standards organizations of thefollowing countries are bound to implement this European Standard: Austria, Belgium, Czech Republic,Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

EN 12101-3:2002 (E)4IntroductionSmoke and heat exhaust ventilation systems create a smoke free layer above the floor byremoving smoke and thus improve the conditions for the safe escape and/or rescue of peopleand animals and the protection of property and permit the fire to be fought while still in itsearly stages. They also exhaust hot gases released by a fire in the developing stage.The use of smoke and heat exhaust ventilation systems to create smoke free areas beneath abuoyant smoke layer has become widespread. Their value in assisting in the evacuation ofpeople from construction works, reducing fire damage and financial loss by preventing smokelogging, facilitating fire fighting, reducing roof temperatures and retarding the lateral spreadof fire is firmly established. For these benefits to be obtained it is essential that smoke andheat exhaust ventilators operate fully and reliably whenever called upon to do so during theirinstalled life. A heat and smoke exhaust ventilation system is a scheme of safety equipmentintended to perform a positive role in a fire emergency.Components for smoke and heat exhaust systems should be installed as part of a properlydesigned smoke and heat system.Smoke and heat exhaust ventilation systems help to— keep the escape and access routes free from smoke;— facilitate fire fighting operations by creating a smoke free layer;— delay and/or prevent flashover and thus full development of the fire;— protect equipment and furnishings;— reduce thermal effects on structural components during a fire;— reduce damage caused by thermal decomposition products and hot gases.Depending on the design of the system and the ventilator, powered or natural smoke and heatventilators can be used in a smoke and heat control system. Powered smoke and heat exhaustventilators can be installed in the roof or upper part of walls of building or in a ducted systemwith the ventilator inside or outside the smoke reservoir or in a plant room.Powered smoke and heat exhaust ventilation systems should operate based on poweredventilators. The performance of the powered smoke and heat exhaust system depends on— the temperature of the smoke;— size, number and location of the exhaust openings;— the wind influence;

EN 12101-3:2002 (E)5— size, geometry and location of the inlet air openings;— the time of actuation;— the location and conditions of the system (for example arrangements anddimensions of the building).Smoke and heat exhaust ventilation systems are used in buildings or construction workswhere the particular (large) dimensions, shape or configuration make smoke controlnecessary.Typical examples are:— single and multi-storey shopping malls;— single and multi-storey industrial buildings and warehouses;— atria and complex buildings;— enclosed car parks;— stairways;— tunnels;— theatres.Depending on differing circumstances and the situation of the building or construction worksthat can affect their performance, powered or natural smoke and heat exhaust ventilationsystems may be used.It is specified in parts 4 and 5 of this European Standard that powered and natural exhaustventilators should not be used to extract smoke and hot gases from the same smoke reservoir.Special conditions apply where gas extinguishing systems (e.g. according to prEN 12094 orISO 14520-1) are used (see parts 4 and 5).

EN 12101-3:2002 (E)61 ScopeThis European standard specifies requirements and gives methods for testing powered smokeand heat exhaust ventilators that are intended to be installed as part of a powered smoke andheat exhaust ventilation system. It also provides a procedure for approving a range ofpowered smoke and heat exhaust ventilators and their motors, from a limited number of tests.2 Normative referencesThis European Standard incorporates, by dated or undated reference, provisions from otherpublications. These normative references are cited at the appropriate place in the text and thepublications are listed hereafter. For dated references, subsequent amendments to or revisionsof any of these publications apply to this European Standard only when incorporated in it byamendment or revision. For undated references the latest edition of the publication referred toapplies (including amendments).EN 1363, Fire resistance tests.EN 1366, Fire resistance tests for service installations.EN 60034-1, Rotating electrical machines, rating and performance.IEC 34-2, Methods for determining losses and efficiencies from test.ISO 834-1, Fire resistance tests. Elements of building construction - Part 1: Generalrequirements for fire resistance testing.EN ISO 5167, Measurement of fluid flow by means of pressure differential devices.ISO 5221, Air distribution and air diffusion. Rules for methods of measuring air flowrate inan air handling duct.ISO 5801, Industrial fans, performance testing using standardized airways.prEN 12101-2:1995, Smoke and heat control systems - Part 2: Specification for natural smokeand heat exhaust ventilators.

EN 12101-3:2002 (E)73 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply:3.1smoke and heat control systemarrangement of components installed in a construction work to limit the effects of smoke andheat from a fire3.2smoke and heat exhaust systemsmoke control system that exhausts smoke and heat from a fire in a construction work or partof a construction work3.3smoke and heat exhaust ventilation system (SHEVS)smoke and heat exhaust ventilation system consists of components jointly selected to exhaustsmoke and heat to establish a buoyant layer of warm gases above cooler, cleaner air3.4natural ventilationventilation caused by buoyancy forces due to differences in density of the gases because oftemperature differences3.5powered ventilationventilation caused by the positive displacement of gases through a ventilatorNOTE

Fans are usually used.3.6ventilatordevice for enabling the movement of gases into or out of a construction work3.7exhaust ventilatordevice for the movement of gases out of the construction work

EN 12101-3:2002 (E)83.8smoke and heat exhaust ventilatordevice specially designed to move smoke and hot gases out of the construction work underconditions of fire3.9dual purpose ventilatorsmoke and heat exhaust ventilator that has provision to allow its use for comfort (i.e. day today) ventilation3.10emergency ventilatorsmoke and heat exhaust ventilator that is not used for comfort (i.e. day to day) ventilation3.11permanently open natural smoke and heat exhaust ventilatorsmoke and heat exhaust ventilator without devices for closing3.12manually opened natural smoke and heat exhaust ventilatorsmoke and heat exhaust ventilator that can only be opened by a manual control or releasedevice3.13automatic natural smoke and heat exhaust ventilatorsmoke and heat exhaust ventilator which is designed to open automatically after the outbreakof fire if called upon to do soNOTE

Automatic natural smoke and heat exhaust ventilators may also be fitted with a manualcontrol or release device.3.14automatically initiated powered smoke and heat exhaust ventilatorpowered smoke and heat exhaust ventilator that operates automatically after the outbreak offire if called upon to do so

EN 12101-3:2002 (E)93.15smoke reservoirregion within a building limited or bordered by smoke curtains or structural elements andwhich will in the event of a fire retain a thermally buoyant smoke layer3.16hot gas fanfan that is suitable for handling hot gases for a specified time/temperature profile. The timemay be “continuous” or more specific to the application. Special materials may beincorporated in the fan that may have a direct or indirect drive. The motor may be in theairstream on a direct drive fan or separated from it by a bifurcation tunnel. Indirect drive fansmay incorporate a means of cooling belts, bearings or other drive components3.17powered smoke and heat exhaust ventilatorhot gas fan that is suitable for handling hot gases for a limited period only3.18powered roof ventilatorpartition fan designed for mounting on a roof and having exterior weather protection3.19insulated ventilatorventilator insulated to limit the external surface temperature to reduce the danger of injury topersons or damage to materials3.20smoke reservoir ventilatorventilator suitable for operation fully immersed in a smoke reservoir3.21non smoke reservoir ventilatorventilator not suitable for operation fully immersed in a smoke reservoir

EN 12101-3:2002 (E)103.22powered ventilator product rangephysically similar ventilators using the same form of construction and materials throughout,with the same methods of impeller construction and motor mounting and construction, andelectrical connection in which the following may vary across the range:— overall dimensions of units; and/or— the impeller diameter and width, hub size, blade length and number of blades ofthe impeller; and/or— the size of the motor3.23powered ventilator motor rangemotors which are physically similar, using the same form of construction i.e. same materialsand manufacturing method for carcase, cooling impeller, when fitted, and end covers; sameinsulation specification which includes sheet insulation used on for coil separation and slotinsulation, winding impregnation material (varnish or resin etc... ,lead insulation, terminalblocks and any other materials that could affect the integrity of the insulation); same bearingtype, class of fit, lubricant and arrangement, with motor windings based on the samemaximum winding temperature and class of insulation, in which the following may varyacross the range:— the frame size;— the rotational speed;— the electrical windings, including multi-speed;— the form of mounting, e.g. foot, flange, pad, clamp, etc.3.24motor ratingthe motor rating (rated power) is the maximum power that the motor will deliver continuouslywithout exceeding the allowable temperature rise3.25fire positionposition of a component to be reached and maintained while venting smoke and heat

EN 12101-3:2002 (E)114 Design requirements4.1 Application classesA powered ventilator shall be classified into one or more of the following application classes:— insulated or uninsulated;— smoke reservoir or non smoke reservoir;— dual purpose or emergency only use;— ducted cooling air required.4.2 Motor rating4.2.1 The motors shall be selected for continuous operation at the power required for normalambient temperature not just for operation at high temperature.4.2.2 Motor ratings shall be limited either by the temperature rise for one class lower than theinsulation class of the motor, as defined in EN 60034-1, as given in Table 1, or for motorswith class B or class F insulation to the motor rated output power being 15 % above theabsorbed power at a density of 1,2 kg/m3.Table 1 — Motor temperature ratingsMotor insulationTemperature rise at ambientClass H or CClass FClass FClass BClass BClass E4.3 Motor specificationMotors shall comply with the requirements of EN 60034-1.5 General testing proceduresFor type approval, tests shall be carried out in accordance with annex A, B, C, D and E. Foreach test a test report shall be prepared in accordance with annex C and/or D.

EN 12101-3:2002 (E)126 Performance requirements and classification6.1 Temperature/time classification6.1.1 A ventilator shall be classified as a)

F200; or b)
F300; or c)
F400; or d)
F600; or e)
F842 or f)

Not classified6.1.2For products intended to be installed within a building, there shall be no significantleakage of smoke from the furnace coming from the housing of the ventilator during theentire test period6.1.3At the appropriate temperature given in Table 2, a ventilator shall function for not lessthan the appropriate minimum time, and shall re-start, when tested in accordance withannex C.Table 2 — Test temperature and functioning time according toclassificationClassTemperatureMinimum functioning period°CminutesF200200120F30030060F400400120F60060060F84284230Not classifiedas specifiedas specifiedby sponsorby sponsor6.2 Flow and pressureWhen tested in accordance with annex C, at the appropriate temperature and for theappropriate time given in Table 2, the volume flow shall not change by more than 10 % or thestatic pressure shall not change by more than 20 % of that measured at the end of the warm upperiod of the test.

EN 12101-3:2002 (E)136.3 Outer surface temperature and cooling air temperature of insulated ventilatorsWhen the ventilator is tested in accordance with annex C, at the temperature and for the timeappropriate to the product temperature/time category:The outer surface temperature of an insulated ventilator shall not increase by more than180 °C for any individual value.The cooling air expelled from the unit shall not exhibit an increase of temperature of morethan 180 °C from the initial room temperature.NOTE

Increases above those specified may increase the fire risk.6.4 Wind loadIf the ventilator is designed to be installed at the atmospheric termination of a system and isfitted with flaps or louvres and these project above the wind deflectors (cowl or wind shield),the flaps or louvres shall open in less than 30 s against of a load of 200 Pa, when theventilator is tested in accordance with annex E.6.5 Snow load6.5.1 If the ventilator is designed to be installed at the atmospheric termination of a system,the ventilator shall be classified as one of the following:— SL 0— SL 125— SL 250— SL 500— SL 1000— SL ANOTE

The designations 0, 125, 250, 500, 1000 and A represent the test snow load in Pascalsapplied when the ventilator is tested in accordance with annex E The "A" in SLA will be replaced bythe test snow load when this exceeds 1000, or by the test load if one of the four defined values is notused.Where the minimum angle of installation (combining roof pitch and ventilator pitch)recommended by the supplier exceeds 45°, the ventilator takes the classification SL 1000without a test; except where the snow will be prevented from slipping from the ventilator e.g.by wind deflectors.

EN 12101-3:2002 (E)14If the ventilator is fitted with deflectors, the snow load classification shall not be less thanSL=2000 d where d is the depth of snow, in metres, which can be contained with the confinesof the deflectors.6.5.2 The ventilator shall open in its fire open position in not more than 30 s after actuationwhen tested under the snow load appropriate to its classification in accordance with annex E.NOTE

The following types of ventilators may be suitable for use on heated buildings without asnow load classification test:a) vertical discharge units without flaps or dampers;b) vertical discharge units with uninsulated metal flaps or dampers.6.6 Operation at low temperatureA powered ventilator with a separate device for the operation of the dampers, flaps or louvres,which does not use the air pressure from the fan, shall conform to 7.3 of prEN 12101-2:1995,when tested in accordance with annex E of prEN 12101-2:1995.6.7 ReliabilityA powered ventilator with dampers, flaps or louvres or a separate device for the operation ofthe dampers, flaps or louvres, which does not use the air pressure from the fan, shall conformto 7.1 of prEN 12101-2:1995 when tested in accordance with annex C of prEN 12101-2:1995.6.8 Performance data of ventilators6.8.1 The supplier shall provide a data sheet giving the aerodynamic and acousticperformance data of the ventilator assessed at ambient temperature in accordance withISO 5801, taking into account the reduction in performance caused by the increasedclearances required for high temperature.NOTE

It is permissible to convert these figures to determine the performance with hot gases and atother speeds of rotation using the scaling formulae from ISO 5801, with due allowance for tipclearance effects.6.8.2 If a ventilator is designed to be fitted with a duct for cooling air the data sheet shallinclude the volume pressure characteristic of the auxiliary system and the minimum coolingair flow required.

EN 12101-3:2002 (E)157 MarkingThe ventilator shall be marked with the following: a)

the name or trade mark of the supplier, and b)
the type and model; and c)
the application classes; and d)
the temperature/time category; and e)
the maximum exhaust temperature in °C; and f)
the functioning period in minutes; and g)
the year of manufacture; and h)
technical data such as power, current, voltage, pressure, volume flow; and i)
the motor insulation class; and j)
the snow load class; k)

the number and the year of this European Standard.Where the requirements of annex ZA.3 give the same information as above, the requirementsof this clause (7) shall be considered to have been met.8 Evaluation of conformity8.1 GeneralThe compliance of powered smoke and heat exhaust ventilators with the requirements of thisstandard shall be demonstrated by:- initial type testing,- factory production control by the manufacturer.8.2 Initial type testingInitial type testing shall be performed on first application of this standard. Tests previouslyperformed in accordance with the provisions of this standard (e.g. same product, samecharacteristic(s), test method, sampling procedure, system of evaluation of conformity) maybe taken into account. In addition, initial type testing shall be performed at the beginning ofthe production of a new product type or at the beginning of a new method of production(where these may affect the stated properties).All characteristics given in clauses 5 and 6.1 to 6.7 shall be subject to initial type testing.

EN 12101-3:2002 (E)168.3 Factory production control (FPC)The manufacturer shall establish, document and maintain an FPC system to ensure that theproducts placed on the market conform with the stated performance characteristics. The FPCsystem shall consist of procedures, regular inspections and tests and/or assessments and theuse of the results to control raw and other incoming materials or components, equipment, theproduction process and the product, and shall be sufficiently detailed to ensure that theconformity of the product is apparent.An FPC system conforming with the requirements of the relevant part(s) of EN ISO 9000,and made specific to the requirements of this standard, shall be considered to satisfy theabove requirements.The results of inspections, tests or assessments requiring action shall be recorded, as shall beany action taken. The action to be taken when control values or criteria are not met shall berecorded.

EN 12101-3:2002 (E)17Annex A(normative)Type approval schedule for a range of ventilatorsA.1 Reduction of numbers of tests for ventilators forming a product rangeFor the purpose of type approval it is not usually considered necessary to test every size ofventilator in a product range provided that the following are tested and the range complieswith the rules given in A.3 and A.4 and annex B: a)

the ventilator with the most highly stressed impeller, or the ventilators withimpellers in which the individual stress in any material, weld or fastening is thehighest, as appropriate (see A.4); b)

for ventilators with motors mounted in an enclosure which restricts the cooling, theworst case shall be tested, for example the ventilator with the ratio of motor crosssectional area to the minimum cross sectional area through which the cooling airflows; c)

at least two sizes are tested at their highest rotational speed; d)
the ventilator with the smallest motor frame size to be used; e)

if the highest impeller stress levels are determined by geometric similarityconditions from A.4.1, sufficient sizes of ventilators to ensure that the impellerdiameters of the range are from 0,8 to 1,26 of those tested; f)

if the highest impeller stress levels are determined by the calculation methods inA.4.2, sufficient sizes of ventilators to ensure that the impeller diameters of therange are from 0,63 to 1,26 of those tested.A.2 MotorsA product range shall only be approved if the motors used in the range are also approved,except when the impeller is not mounted on the motor shaft and the motors are out of theairstream in ambient air and the cooling of the motor is not affected by heat transfer from theventilator or the ventilator construction. When the motor is out of the airstream and theimpeller is mounted on the motor shaft, motors from a different supplier to the one used inthe ventilator test may be used, provided that the tested and alternative motors are of the sameconstruction, i.e. same class of insulation and bearing type and class of fit and samesynchronous speed and rating.A.3 Combined testingThe tests to approve ventilators and motors may be performed at the same time. The motorapproval procedure is given in annexes B and D. Motors tested independently of fans or inanother range of ventilators may also be used provided these tests have been undertaken withsimilar mechanical loads and cooling conditions as described in this annex and annex D.

EN 12101-3:2002 (E)18A.4 Determination of highest stresses in impellersA.4.1 Ventilators with geometrically similar impellers.For geometrically similar impellers the impeller with the highest peripheral speed is the mosthighly stressed.Impellers are geometrically similar if all dimensions, excluding thickness of materials, arewithin 5 % and the thickness of materials is within + 10 % of the values scaled by the ratio ofthe impeller diameters, and the numbers of blades and fastenings are identical. The centreboss is excluded from the geometric similarity requirements.A.4.2 Ventilators with impellers that are not geometrically similar.NOTE

The method given for calculating stresses is for comparative purposes only and is notsuitable for design assessment. It only takes into account centrifugally induced stresses asaerodynamically induced stresses are of less importance.A.4.2.1 Axial impellersA.4.2.1.1 Centrifugal forceDivide the blade into four parts using five sections as shown in Figure A.1.Calculate the centrifugal force for each part as follows2n1nn1n1nn1+nn,2)()-(2)(RRRRAAFWhereFn,n+1is the centrifugal force in Newtons of the part of the blade between sections nand n+1; is the density in kg/m3;Anis the area of section n in m2;Rnis the radius of section n;is the angular velocity in radians/s.

EN 12101-3:2002 (E)19Figure A.1 — Axial impeller, blade divided into four parts using five sectionsCalculate the tensile stress as follows, see Figure A.2.Fn = Fn,n+1 + ......... +F4,5Tn = FnAn/106WhereTnis the tensile stress in N/mm2;nis the number of the section.Figure A.2 — Axial impeller, application of centrifugal force

EN 12101-3:2002 (E)20A.4.2.1.2 Fastenings or weldsTreat fastenings or welds as the inboard end of the blade section with the cross section areacalculated from the weld or fastener area.A.4.2.1.3 Hub/backplate/shroud stressesConsider only forces due to centrifugal effects. The stresses on the hub are a combination ofthe self induced stress due to the rotation of the hub, the hoop stress due to the loads imposedby the blades, and the bending stress due to the point loads of the blades.6hsi1022=xRxWheresiis the self induced stress in N/mm2;Rhis the maximum hub radius in m;is the angular velocity in radians/s;is the density in kg/m3.Assume that only the section of the hub/backplate/shroud approximately symmetrical aboutthe plane of rotation through the centre of the blade fixing is supporting the blades, see FigureA.3, then calculate the hoop stress,h51h2AFN/.Wherehis the hoop stress in N/mm2,Nis the number of blades,F1-5is the total blade centrifugal force in Newtons,Ahis the cross sectional area of the hub in mm2.Calculate the section modulus about an axis through the section centre of area, parallel to theaxis of rotation, using the distance to the outside of the hub/backplate/shroud supporting theblade. Then calculate the bending stress.)ZxxN/(RxxCFhb122=51

EN 12101-3:2002 (E)21Wherebis the bending stress in N/mm2,Zis the section modulus in mm3,Then using linear hypothesisTotal stress = si + h + bFigure A.3 — Portion of hub to be used for calculationNOTE

Shaded parts show portion to be used for calculation.

EN 12101-3:2002 (E)22A.4.2.2 Centrifugal impellersA.4.2.2.1 Centrifugal forceThe centrifugal force is calculated by treating the blade as one piece, as follows2=xRxlxAxFbWhereFis the centrifugal force in N,is the density of blade material in kg/m3,Abis the cross section area of the blade at the centre of gravity, perpendicular tothe axis of rotation in m2,1is the distance between the backplate and shroud, through the centre of gravity,parallel to the axis of rotation, in m,Ris the radius of blade centre of gravity about the axis of rotation, in m,is the angular velocity of

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