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Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to

information for citizens to secure access to information under the control of public authorities,in order to promote transparency and accountability in the working of every public authority,

and whereas the attached publication of the Bureau of Indian Standards is of particular interest

to the public, particularly disadvantaged communities and those engaged in the pursuit of

education and knowledge, the attached public safety standard is made available to promote the

timely dissemination of this information in an accurate manner to the public.

!"#$% '(%)

!"# $ %& #' (")* &" +#,-.Satyanarayan Gangaram Pitroda

Invent a New India Using Knowledge

/0)"1 &2 324 #' 5 *)6Jawaharlal Nehru

Step Out From the Old to the New

7"#1&"8+9&"), 7:1&"8+9&")Mazdoor Kisan Shakti Sangathan

The Right to Information, The Right to Live

!"# %& ;

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I ndian St andardIS 5 4894 9 1987

SPECIFICATION FORCENTRIFUGAL FANS( Fi rst , v i si on )

UDC 621.635-83

Q Copyright 1988

( Reaffirmed 1999 )

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IS I 4894 - 1987I nd ian Standard

SPECIFICATION ORCENTRIFUGALFANS

F i r st Revi si onO FOREWORD

0.1 This Indian Standard ( First Revision ) wasadopted by the Bureau of Indian Standards on27 August 1987, after the draft finalized by theElectric Fans Sectional Committee had beenapproved by the Electrotechnical DivisionCouncil.0.2 This standard was originally published in1968. This revision has been undertaken to takeinto account the experience gained since then andto align some of the safety requirements with theprovisions of IS : 302-1979*. The amendmentsissued to the previous edition of the standardhave also been incorporated in this revision.0 3 The centrifugal fans covered by this standard

*General and safety requirements for household andsimilar electrical appliances ( jifth rez~ision .

are capable of working against pressures.0.4 In preparing this standard, some assistancehas been drawn from BS 848 : Part 1 : 1980Fans for general purposes : Part 1 Methods oftesting performance, issued by the British Stand-ards Institution.0.5 For the purpose of deciding whether a parti-cular requirement of this standard is compliedwith, the final value, observed or calculated,expressing the result of a test, shall be roundedoff in accordance with IS : 2-1960*. The numberof significant places retained in the rounded OKvalue should be the same as that of the specifiedvalue in this standard.

*Rules for rounding off numerical values ( revised .

1. SCOPE1.1 This standard covers the requirements andtests for centrifugal fans having impeller directlycoupled to the shaft of electric motors or indire-ctly driven by electric motors. In the case ofindirectly driven fans, the electric motor shallconform to the relevant Indian Standard.I.2 The fans for use under free flow conditionsare excluded from the scope of this standard.1.3 Centrifugal fans for use in mines and hazar-dous atmospheres may require additional requi-rements to be met, not covered by this standard.2. TERMINOLOGY2.0 For the purpose of this standard, the follow-ing definitions, in addition to those given in IS :1885 ( Part 55 )-1981*, shall apply.2.1 Centrifugal Fan - A fan in which the airleaves the impeller in a direction substantially atright angles to its axis.2.2 Fan - A rotary machine which maintains acontinuous flow of air at a pressure ratio notnormally exceeding 1.3.

*Electrotechnical vocabulary: Part 55 Electric fans.1

NOTE In this specification, the term fan shallbe used to mean centrifugal fan as supplied, withoutany addition to the inlet or outlet, except where suchaddition is specified.2.3 Air - The term air has been used as anabbreviation for air or anwhere referred to as atmosp K other gaseric air. except2.4 Standard Air - Atmospheric air having aspecified weight of 1.2 kg/m3 which is dry air at20C with a barometric pressure of 760 mm Hg(W2.5 Absolute Pressure - That pressure whichis exerted equally in all directions at a point.The absolute pressure of the ambient atmosphereis the barometric pressure.2.6 Static Pressure - The difference betweenthe absolute pressure at a point and absolutepressure of the ambient atmosphere. It is positivewhen above and negative when below the ambi-ent pressure.2.7 Velocity Pressure - The pressure equival-ent of the air velocity at any particular point. Itis always positive.2.8 Total Pressure - The algebraic sum of thestatic pressure and velocity pressure at any parti-cular point.

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IS : 4894 - 19872.9 Fan Total Pressure Pt) - The algebraicdifference between the total pressure at the fanoutlet pressure and the total pressure at the faninlet ( see also Fig. 1 ).

NOTE - The difference in pressures is the meanpressure when facing tube reading is employed.2.10 Fan Velocity Pressure P, - Thevelocity pressure corresponding to the averagevelocity at the fan outlet based on the total out-let area.2.11 Fan Static Pressure ( P, - The differ-ence between the fan total pressure and the fanvelocity pressure at the fan outlet.2.12 Inlet Volume - The volume per unit timeof air entering the fan ( Q) expressed in ms/h.2.13 Air Power ( Total ) - That part of theenergy, per unit time, imparted by the fan to theair in increasing its total pressure from that atthe inlet to that at the outlet.2.14 Air Power Static ) - This is equal tothe air power ( total ) minus the nominal kineticenergy per unit time at the outlet.2.15 Impeller Power - The energy input perunit time to the fan impeller.2.16 Shaft Power - The energy input per unittime to the fan shaft including the power absor-bed by such parts of the transmission system asconstitute an int egral part of the fan, for example,fan shaft bearings.2.17 Fan Duty ( Total ) - The inlet volumedealt with by the fan at a stated fan totalpressure.2.18 Fan Duty ( Static ) - The inlet volumedealt with by the fan at a stated fan staticpressure.2.19 Fan Total Efficiency - The ratio of theair power ( total ) to the impeller power,2.20 Fan Static Efficiency - The ratio of theair power ( static ) to the impeller power.2.21 Average Fan Total EBkiency - Theratio of the air power ( total ) to the shaftpower.2.22 Average Fan Static Efficiency - Theratio of the air power ( static ) to the shaftpower.2.23 Side Tube or Static Pressure Tube - Atube which allows air to flow without disturbancepast one or more small orifices having their axisat right angles to the direction of air stream inwhich it is placed.2.24 Side Tapping or Static Pressure Tapping - A small opening in the wall of an airway,having its axis at right angles to the wall and so

constructed as to allow the air to flow past with-out disturbance.2.25 Facing Tube or Total Pressure Tube -An open-ended tube, the axis of which is coinci-dent with the direction of the air stream in whichit is placed. the open-end facing upstream, thatis, against the directibn of flow.2.26 Pitot Tube - A combination of side tubeand facing tube as one unit.2.27 Size of Fan - The blade sweep in milli-metres, the blade sweep being the diameter ofthe circle traced by the periphery of the impeller.This is also commonly known as wheel diameter.2.28 Cooling Air Temperature - The tempe-rature of the surrounding atmosphere in whichthe fan operates.

2.29 Rating2.29.1 Fan Performance Rating - The workcapable of being done by the fan over its entire

range of operation expressed in terms of volumehandled per unit time against total pressuregenerated at shaft powers indicated. This isnormally shown in graphical fashion, followingperformance tests carried out in accordancewith 10.2.29.2 Point of Rating of a Fan - A statementof fan performance for one condition of operation

and includes fan size, volume, pressure andhorsepower, to which fan laws are applicable.2.30 Type Tests - Tests carried out to proveconformity with the requirements of this stand-ard. These are intended to prove general quali-ties and design of given type of fan.2.31 Routine Tests - Tests. carried out oneach fan to check the essential requirementswhich are likely to vary during production.2.32 Acceptance Tests - Tests carried out onsamples selected from a lot for the purpose ofverifying the acceptability of the lot.

2.32.1 Lot - All fans of the same type, grade,category and rating, manufactured by the samefactory during the same period, using the sameprocess and materials.3. SIZES3.1 The following shall be the preferred sizes:

150, 225, 300, 375, 450, 600, 750, 900, 1 200and 1 500 mm.NOTE - Sizes of fans specified above are subject toa tolerance of f 5 mm.

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IS : 4894 - 1987BOOSTER FAN

BLOWING FAN

FAN STATICPRESSUREFAN TOTALPRESSURE FAN TOTALPRESSURE

1A Fan Ducted at Outlet only 1 B Fan Ducted at Outlet and Inlet

EXTRACT FAN

1C Fan Ducted at Inlet onlyFIG. 1 DIAGRAMMATIC LL USTRATIONSOF FAN PRESSUREDEFINITIONS

4. RATED VOLTAGE4.1 The preferred rated voltages for centr ifugalfans shall be 230 and 240 V, single-phase; and400 and 415 V, 3-phase ( see IS : 585-1962* ).5. RATED FREQUENCY5.1 The rated frequency shall be the standardfrequency of 50 Hz.

NOTE - Nevertheless, fans made for other freque-ncies shall be considered to comply with the specifica-tion provided they do so in all other relevant respects.6. DESIGN AND GENERAL CONSTRUC-TION6.1 Motor Enclosure - The enclosure of thefan motor shall be of the totally enclosed type orSPDP.6.2 Rotor - The rotor of the fan motor shall bewell-balanced.6.3 Blades - Fans shall be fitted with an impe-ller consisting of a number of blades or vanesmade from metal or other suitable material. The

*Specification for voltages and frequency for ac trans-mission and distribution systems ( revised ).

impeller assembly shall be securely fixed so thatit does not loosen in operation.6.4 Mounting - The mea.ns provided for secur-ing the fan mounting or fan casing shall be suchas to provide a secure fixing. Where the casingcontains members to be clamped against anexterior wall, these shall be capable of beingsealed to prevent the ingress of rain-water at tnepoint of attachment.6.5 Guards - Suitable designed guards shall bemade available by the manufacturer for supplyon request and shall be fitted either to the inletor the outlet or both, to prevent accidental con-tact with the rotating blades. The guards shallbe securely attached and shall be adequately rigidto resist accidental contact with the blades. Whenthe guards are in two pieces, positive lockingarrangement to keep the two pieces togethershould be made.6.6 Bearings - I f necessary, the manufacturershall, on inquiry, furnish information about thetype of bearing and instructions for their properlubrication ( see9.1.2 ). Proper types of bearingsshould be used to ensure a reasonable amount ofsilent operation.

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IS : 4894 - 19876.7 Protective Measures - The fans shallhave protective electrical insulation or be capableof being earthed. A fan with protective electricalinsulation may be of all-insulated construction orhave either double insulation or reinforcedinsulation.

6.7.1 In the case of fans intended to beearthed, an earthing terminal of adequate current-carrying capacity conveniently located and easilyaccessible shall be provided. In the case of fansfor use on three-phase, two separate earthingterminals shall be provided.6.8 Capacitors - Capacitors, if any, shall beeasily replaceable and placed at sufficient distancefrom the windings so that their maximum work-ing temperature is not exceeded Capacitors shallbe clearly marked with the maximum safe work-ing temperature, and the corresponding voltageand capacitance. Capacitors shall comply withIS : 1709-1984*.7. GENERAL AND SAFETY REQUIRE-MENTS7.1 Protection Against E lectric Shock - Inthe assembled fan, live parts shall not be accessi-ble to the standard test finger ( see IS : 1401-1970? ). In the case of a double insulated fan,both basically insulated parts and live parts shallnot be accessible to the standard test finger. Thisrequirement is applicable for all positions in thenormal use.7.2 Electric Insulation - The electric insula-tion of the fans shall be adequate and the leakagecurrent in normal use shall not be excessive.

7.2.1 When measured according to the methodspecified in 10.5, the insulation resistance shallnot be less than 2 Ma.7.2.2 Leakage Current - Requirements of therelevant Indian Standards on motors shall apply.The leakage current which may flow from thelive parts to the accessible parts and metal foil onexternal insulating material connected togethershall not exceed 300 PA peak ), that is 210 PA( rms ).7.2.3 There shall be no breakdown of theinsulation when the fan is subjected to highvoltage test as given in 10.3 or flash test ( IO.4 ),as the case may be.

7.3 Insulating Materials - Windings of fansand regulators ( where provided ) shall be insula-ted with either Class A, Class E or Class Binsulating materials which comply with the limitsof temperature-rise specified in 7.4. These insulat-ing materials are detailed in IS : 1271-1985 .*Specification for capacitors for electric fan motors.(first raGsion .tSpecification form&ion ) . accessibility test probes (psiThermal evaluation and classification of electricalinsulation ( Jrst revision ) .

7.4 Temperature-Rise - The fan motor andthe regulator shall be tested at any cooling airtemperature not exceeding 40C, but whatevermay be the value of this temperature, the permi-ssible temperature-rise when measured as descri-bed in 10.13.2 shall not exceed the limits givenin Table 1.TABLE PERMISSIBLE LIMITS OFTEMPERATURERISE

SL PART OBNo. MOTOR onREWJLATOB

(1) (2)i) Insulated win-dings ofmotorsii) Insulated win-

dings, if any,of regulator( with conti-nuous runn-ing on anycontact )iii) Regulator resi-stance unit( with conti-nuous runn-ing on anycontact )iv) External surfa-ces likely tobe touchedduring normalusage

TEMPERATURE-RISE. Cclass A Class E Class3Insula- Insula- Insula-tion tion tion

(3) (4) (5)60 75 80

60 75 80

The temperature-rise shallnot reach such a valuethat there is a risk ofinjury to any insulatingmaterial on adjacentparts of the regulator40 40 40

METHODMZl-nEME?JT

(6)%Ze _stanceChangeof resi-stance

Thermo-meter

Thermo-meter

NOTE 1 - The thermocouples, if used, should beapplied only to external surfaces which may be reachedby an ordinary thermometer.NOTE 2 - The temperature-rise values given aboveare for fans normally made to this specification to workin cooling air temperatures not exceeding 40C. Never-theless, fans made to work in higher cooling air tem-peratures may be regarded as complying with thisspecification provided the temperature-rise values arereduced corresponding to the increase in cooling airtemperature. Such fans shall be specially marked.

7.5 Finish - All the surfaces of fan motor,blades and regulator, if any, shall be of corrosionresisting material or shall be suitably and durablyprotected against corrosion for specific applica-tiOIlS.7.6 Speed Regulators

7.6.1 It is not usual for fans covered by thisspecification to be provided with regulators.However, if regulators are required, this shall bea matter of agreement between the purchaser andthe supplier.7.6.2 Enclosures of the fan regulators shall beeither of the ventilated type or the totally-enclosed type.

4

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IS t 4894 - 19877.6.3 Where a regulator is provided with acapacitor not permanently connected across themotor terminals, provision shall be made so thatthe capacitor is discharged when the regulator isin the OFF position.7.6.4 The regulator handle or knob or pushbuttons shall either be of insulating material or,if of metal, shall be adequately insulated electri-cally and thermally so that its temperature-riseabove ambient is limited to 20C. All metallicparts associated with it shall be protected fromaccidental contact.7.6.5 The regulator handle or knob shall be soplaced that it may be safely and convenientlymanipulated with definite positioning action. Thehandle or knob shall be so designed that it doesnot become loose in use. The Running andOFF positions of the regulator shall be distinctlyand clearly marked and the indicator on theoperating handle or knob shall correctly indicate

the position of the regulator.7.6.6 The regulators shall have mechanicalstops for the regulator moving contact to preventaccidental contact with the metallic body of theregulator in the event of forced overtravel of theknob.7.6.7 The mechanism of the regulator shall beso designed as to ensure positive contact at eachrunning position. In the case of inductance typeregulator, it is essential that no portion of theinductive winding should remain permanentlyshort-circuited in any of the running positions.

7.7 Interchangeability - The motor of the fanof a particular size and model and its associatedregulator and set of blades shall be interchange-able such that the performance of the fan keepswithin the limits of standard.7.8 Silent Operation - Precautions shall betaken in the manufacture of fans and regulators

to ensure a reasonable degree of silence at allspeeds.NOTE The need for specifying limits of noiaelevels ( acoustical ) of the fans is recognized. However,it has not been found possible to specify these limits atpresent on account of:

a) dependency of these limits on the actual locationof the fans,b) lack of data on the acceptable noise levels fordifferent applications, andc) lack of agreed definition of noise level and methodof evaluating the same.

The criterion of noise level may, therefore, besubject to an agreement between the manufac-turer and the purchaser.8. PERFORMANCE REQUIREMENTS8.1 Air Delivery Test - This test shall becarried out and calculations made in accordancewith 10.12.8.2 Fan Characteristics - Fan characteristiccurves shall be drawn after testing, consideringnot less than three test points determining a shortpart of the fan characteristic at different inlet.volume flows and corresponding fan total or staticpressure.

A system resistance line shall also be drawn,passing through the specified duty point such thatthe total or static pressure varies with the squareof the inlet volume flow ( see Fig. 2 ).The most probable operating point for the fanshall be at the intersection of the fan characteri-stic and the system resistance line. The differencebetween the inlet volume flow at the intersectionand the specified inlet volume flow ( that is, theduty point ) shall be recorded as the measure ofdeparture of the fan from the specified perfor-mance. This value shall fall within the range ofspecified tolerances.

PtF

h SYSTEM RESISTANCEFAN CHARACTERISTICINLET VOLUME FLOW

p = PressureQv - Inlet volume flow

FIG. 2 EXAMPLE OF FAN CHARACTERISTICCURVE AND TEST FOR A SPECIFIEDDUTY5

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15:4894-1981The fan characteristic may be extended tozero inlet volume and to zero static pressureconditions, but the portion of the characteristicwhich is beyond the range specified by thesupplier shall not be taken into account for thepurpose of performance detailed in Appendix A.

8.3 Tolerances on Ratings - The observedresults expressed as percentage of the ratingsassigned by the manufacturer shall be within thefollowing limits:Characteristic TolerancePercent

Volume flow --5Static or total efficiency ex- - 5pressed as a percentageTotal power input + 16Speed f 10

Where a tolerance in one direction is omitted,there is no restriction on the value in that direc-tion.9. MARKING9.1 Each fan shall be indelibly marked with atleast the following information:

4b)44e)f 1la

Manufacturers name, trade name of fan( if any ) and serial number;Rated voltage(s) or voltage range andnumber of phases;Frequency or range of frequency;Consumption in watts;Size of fan;Rated speed of fan in revlmin;Direction of rotation and direction of airflow;

h) Air delivery at stated duty; and3 Country of manufacture.NOTE - The trade name, voltage and the size ofthe fan shall be marked on associated regulator.

9.1.1 In case of fans provided with earthingterminals, these shall be marked in a legible andindelible manner on or adjacent to these termi-nals with the symbol I

9J.2 For additional information that themanufacturer may be requested to supply, seeAppendix B.9. .3 For additional information that the

purchaser may be requested to supply, seeAppendix C.9.1.4 Centrifugal fans may also be markedwith the Standard Mark.

NOTE The use of the Standard Mark is governedby the provisions of the Bureau of Indian standardsAct 1986 and the Rules and Regulations made there-under. The Standard Mark on products covered by anIndian Standard convevs the assurance that thev havebeen produced to compiy with the requirements of thatstandard under a well-defined system of inspection,testing and quality control which is devised and super-vised by BIS and operated by the producer. Standardmarked products are also continuously checked by BISfor conformity to that standard as a further safeguard.Details of conditions under which a licence for the useof the Standard Mark may be granted to manufacturersor producers, may be obtained from the Bureau ofIndian Standards.10. TESTS10.1 Categories of Tests

10.1.1 Type Tests - The tests specified belowshall constitute type tests and shall be carried outon three samples of same type, size and rating forfans up to and including 600 mm size and onesample of a type, size and rating for larger sizes:4 High voltage ( 10.3 ),b) Insulation resistance ( 10.5 ),C> arthing continuity ( 10.6 ),4 Electrical input ( 10.7 ),e) Fan speed ( 10.8 ),f-1Power factor ( 10.9 ),g>Leakage current ( lo-19 ),h) Starting ( 10.11 ),j> Test for capacitor ( 6.8 ),W Air delivery ( 10.12 ), and4 Temperature-rise ( 10.13 ).10.1.2 Acceptance Tests - The following shallconstitute the acceptance tests:a) High voltage ( 10.3 ),b) Insulation resistance ( 10.5 ),c) Earthing continuity ( 10.6 ),d) Electrical input ( 10.7 ), ande) Fan speed ( 10.8 ).

10.1.2.1 A recommended sampling plan foracceptance tests is given m Appendix D.19.1.3 Routine Tests - The following shallconstitute routine tests:a) Flash test ( 10.4 ),b) Insulation resistance ( IQ.5 , andc) A simplerunning test to determine thatthe fan mechanism is in working order.

10.2 General Conditions of Test10.2.1 Test Voltage and Frequency - Unlessotherwise specified, the test shall be carried out atrated voltage and frequency.

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10.2.1.1 When a rated voltage is indicatedon the name-plate, the test shall be conducted atthe rated voltage. If the fan is specified for two.or more distinct rated voltages with three or moresupply terminals, the tests shall be carried out atthe most unfavourable voltage. In case of doubt,the tests shall be carried. out at all voltages.10.2.1.2 When a rated voltage range isindicated on the name-plate, the test shall beconducted at the mean of the upper and lowerlimits of the range provided that the upper limit*does not exceed the lower limit by more than 10percent.

If the upper limit exceeds this value, the testshall be conducted at the voltage correspondingto either the upper limit or the lower limit which-ever is more unfavourable to the particular test.10.2.1.3 L imi ts of voltage variation - Thevariation in the test voltage shall not exceed f 1percent of the test voltage during air deliverytests. While taking the current and watt read-ings during these tests, however, the voltage shallbe maintained at the test voltage.

10.2.2 For a fan rated with a range of frequ-zncy, the test shall be made at the frequencywhich gives the most unfavourable results. Tole-rance on frequency shall be f 1 percent.10.2.3 Limits of Er ror of Electrical I nstruments -The ammeters, voltmeters and wattmeters usedfor type tests shall have a class index 0.5 or better[ see IS : 1248 ( Part 1 )-1983* 1. For routine andacceptance tests, instruments of class index 2 maybe used.

10.3 High Voltage Test10.3.1 The source of supply for high voltagetest shall be not less than 500 VA.10.3.2 The high voltage test shall be applied

to all new and completed fan motors in normalworking conditions with alI parts in place exceptthe capacitors which should be disconnected. Astype test, this test should preferably be doneimmediately after the temperature-rise test.10.3.3 An ac test voltage at a frequency of40 to 60 Hz approximately sine-wave form shallbe applied and maintained for one minute with-,out showing any kind of breakdown or flashover.The voltage should be applied starting with one-third of the full value, gradually increasing to thefull value which should be maintained for speci-

fied period after which the voltage should begradually reduced.*Specification for direct acting indicating analogue

electrical measuring instruments and their accessories:Part 1 General requirements ( second ~ i on ).

I : 4894 - 1987The test voltage shall be applied as follows:a) For fan motors

1)

2)

3)

Between live parts and otherinaccessible metal parts( that is, over the functionalinsulation ) in the case ofdouble insulated motorsBetween the inaccessiblemetal parts and the body( that is, over the supplemen-tary insulation ) in the caseof double insulated motorsBetween live parts and body( that is, over the reinforcedinsulation ) for reinforcedinsulated motors

b) For regulators ( where provided )Between the two terminalswith the regulator in theOFF position

1 500 v

10.3.4 At the end of one minute, the testvoltage shall be removed and the insulation-resistance test conducted as in 10.5.

1 500 v

2 500 v

4 000 v

10.3.5 If this test is required to .be repeated,the test voltage levels shall be reduced to 85 per-cent of the original value.10.4 Flash Test - Every fan and regulator shallwithstand the voltage 20 percent higher than thatspecified in 10.3.3 for one second when it isapplied instantaneously between the points speci-fied in 10.3.3.

10.4.1 Any other test similar to the one speci-fied in 10.4 may be carried out as a routine testprovided it will ensure the fan passing the highvoltage test covered by 10.3.10.5 Insulation Resistance Test

10.5.1 Insulation resistance test shall be carriedout on fans and regulators immediately afterconducting the high voltage or flash test, as thecase may be.

10.5.2 The insulation resistance shall be notless than 2 megohms when tested with a dcvoltage approximately 500 V applied between thepoints used for high voltage test or flash test.10.6 Earthing Continuity Test - For fansintended to be earthed, the resistance shall notexceed 0.1 ohm between any exposed metal parts,except the rotating parts supported by metalbearings, and

a) the free end of the earthing conductor ifthe fan is fitted with a flexible cord, dueallowance being made for the resistance ofthe earthing conductor of the flexible cord,or

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IS : 4894 - 1987b) the earthing terminal or contact, when thefan is supplied without a flexible cord.The resistance measurement shall be madewith a current of 10A with a dc voltage notexceeding 6V.

10.7 Electrical Input Test - The electricalpower input to the fan in watts shall be determi-ned by running the fan at the test voltage and atthe highest speed.10.8 Fan Speed Test - The speed of rotationof the fan shall be determined by running the fanat the test voltage and its rated frequency. Themethod of measurement of the speed of fan shallbe such that the speed of the fan is not appreci-ably affected.10.9 Power Factor Test - The power factorof the fan when tested at the test voltage and thehighest speed of the fan shall be not less than:

a) 0.90 for capacitor type fans, andY b) 0.60 for non-capacitor type fans.

10.10 Leakage Current Test - This test shallbe carried out in accordance with 13.2 of IS :302-l 979*.10.11 Starting - The fan shall be capable ofstarting up from rest at the lowest speed stepwhen 85 percent of the rated voltage or 85 per-cent of the lowest voltage in the voltage range isapplied.10.12 Air Delivery Test -- The followingmethods for determining the air delivery of thefan at the specified total or static pressure shallbe followed. This test shall be carried out withthe guard if any, in position.

10.12.1 The fan inlets shall be attached witha straight cylindrical airway of diameter D andminimum length 40; D may differ from the faninlet diameter by not more than 20 percent largeror 5 percent smaller; a conical expander orreducer of 15 maximum included angle beingused to connect the fan to the airway.

The fan outlet shall be attached with a para-llel duct having the same cross section as the fanoutlet ( D, and length equal to twice its diame-ter ( 20, ), if circular, or twice the mean of theadjacent sides, if ractangular; provided that noduct shall be fitted to the outlet side of the fanfor the purpose of test in the case of a fan speci-fied or designed for use with open outlet.10.12.2 If the fan is fitted with an inlet flare,the outside diameter of the flare may be regar-

ded as the fan inlet for connection to the testduct. If more convenient, the flare may be remo-ved for the test.*General and safety requirements for household andsimilar electrical appliances ( jifth revision .

10.12.3 The fitting of any additions to thefan for the pupose of this test shall be subject tothe following provisions:a>

b)

cl

4

No additions or alterations solely for thepurpose of a test shall be made to the fanas supplied exept that when an addition tothe fan that may affect its performance hasbeen specified, and unless otherwise agreedto between the manufacturer and the pur--chaser, the addition shall be fitted for thetest. Such an addition shall then be regar-ded as a part of the fan.An allowance shall be made for losses dueto friction of the air in the airway betweenthe fan and the point at which the readings.are taken according to formula givenin 10.12.10(e).In any test, the airways shall be madereasonably air-tight, and when provision ismade for the insertion and manipulationby measuring instruments, care shall betaken to eliminate leakage as far as.possible.Care should also be taken to avoid anyobstructions which may modify the airflow, either at the inlet or at the oultet ofthe airways.

10.12.4 To the inlet end of the test airwayshall be fitted a conical inlet and four side tapp-ings in accordance with Fig. 3 and with thefollowing provisions:a>

b)

The proportions and tolerances of the coni--cal inlet are given in Fig. 3 together withrelevant notes on manufacture and installa-tion. The inlet airway diameter D used inthe computation shall be measured after-manufacture.The four side tappings (see Fig. 4) at plane-AA ( see Fig. 3 ) shall be equally spaced at.90 on the cylindrical duct. The bore at.the surface of the airway shall not exceed4.76 mm in diameter and shall be straight,uniform and at right angles to the duct forat least 2 bore diameters. The openings-shall be flush with the duct and free fromburrs and countersinks. The four sidetappings shall be connected to one limb ofthe manometer, each connection being ofthe same length, bore and arrangement oftubing to minimize the effect of flow dueto difference of pressure at the tappings.The other limbs of the manometer shall beopened to the ambient atmosphere and the.manometer reading shall be taken as equalto the average static pressure in theairway.

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IS : 4894 - 1987THE BORE SHALL BE SMOOTH PARALLEL ANDTRULY CIRCULAR WITHIN A TOLERANCE OF A0FOR A LENGTH OF 0 AND CONTINUED AT SALENOMINAL OIAMETER FOR A FURTHER LENGTH

THE JUNCTION BETWEEN 6OCONE AN0PARALLEL PIPE SHALL BE SMOOTH ANDFREE FROM RIDGES

NO EXTERNAL OBSTRUCTION TO THEFREE MOVEMENT OF AIR ENTERINGTHE INLET IS PERMITTED WITHIN THISREGION. THERE MUST BE NO EXTRANEOUS A IR CURRENTS IN THE VICINITYOF THE I NLET

FIG. 3 CONICAL NLET

1RLIBBER TUBE TO MANOMETER

UBBER TUBES

All dimensionsn millimetres.FIG. 4 METHOD OF CONNECTION OR FOUR SIDE TAPPING TO TEST DUCT AND CONNECTION

TO MASOMETER FOR INDICATIONOF AVERAGE SIZE THROUGHONE BLOCK

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IS : 4894 - 1987c Coeji cient of discharge - The coefficient ofdischarge of the conical inlet installed asabove is given in Table 2. For Reynoldsnumbers of 400 000 and above, the coeffi-cient of discharge is O-975 and will coverthe majority of fan tests. When the airflow, in cubic metres per hour, is numeri-

cally less than 16 700 times the airwaydiameter in metres, then the coefficient ofdischarge shall be taken appropriate to theReynolds number given in Table 2.TABLE 2 DISCHARGE COEFFICIENTS FORREYNOLDS NUMBER Re )

[ C luusc 0.12.4 c) IREYNOLDS 20 0005, 40 000, 60 000, 100 000,NUMBE R (Rc) 200 000, 300 000, 400 000, and aboveDISCHARQE 0.930, 0940, O-945, 0.953, 0.967,COEFFICIENT, CD 0973, 0975

*A conical inlet shall not be used at Reynolds numbersless than 20 000.Intermediate values of Cn may be obtained bylinear interpolation.The Reynolds number for standard air is given

by Re = 23.58 QD using thenotation of 10.12.10and this may be taken to determine the coeffici-ent of discharge with negligible error for allnormal variations in ambient conditions.

10.12.5 A resistance comprising a screen hav-ing evenly spaced aperture of uniform size, notexceeding D/20 should be fitted at a distance Dfrom the commencement of the cylindrical portion

of the inlet. The screen may be composed of oneor more layers of even wire or fabric supportedby a wire guard.1032.6 The various static pressure data maybe obtained by changing the screen or adding-additional screens in .the test duct. If a ring issecured inside the test airway to support thescreen, or when a ring is used to stiffen the peri-phery of the fabric or other screen, the radialthickness of the ring shall not be greater thanD/100 ( see Fig. 5 ).10.12.7 At plane BB, distant 2 D downstreamfrom the resistance screen, there shall be four sidetappings, similar to those in plane AA, and con-nected to the low pressure limb of a moaometer,the other limb being connected to the ambient.pressure in the vicinity of the fan discharge.10.12.8 The volume per unit time at plane AA.shall be computed by using formula ( 1 ) Andycorrected to fan inlet conditions for any changein the air density between plane AA and the faninlet BB.10.12.9 All temperatures in the inlet airwayshall be taken by placing the thermometer withits probe inside the airway near the section BB.The inlet volume so compiled shall then be usedto calculate the velocity pressure at plane BBusing formulae (2) and (3). For the purpose of this.test the algebraic sum ( with the sign reversed )

of the static pressure at plane BB, and the velo-city pressure at plane BB, plus a friction allow-ance for all test ducting downstream of plane BBin accordance with formula (5) shall be taken.as the fan total pressure.

A METHOD OF SUPPORTINGRESISTANCE SCREEN -Fra. 5 ARRANGEME NT F OR AIR DELNERY TEST

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IS : 4894 - 198718.12.10 Formulae and Computat ion of Result s -The following formulae should be used for thecomputation of results of the tests laid downin 10.12.a) Inlet volume perunit time Q= 12500 x CD x

Da I / x ms/hwt . . . . . . (1)wherec, = coefficient of discharge,D= diameter of airway in metres,

AP= difference between ambient pre-ssure in the vicinity of the inletand the average pressure at theside tappings at plane AA in mmHaO, andWt = weight of air in airway at the test

temperature t C in kg/ms.b) Weight per unit volume of atmospheric airat test sectionw t = 1.205 x B + 0.073 7 P, x760

293( 273 + t ) kgms

which may be very closely approximated asw, = l-2 x B + 0.073 7 Ps x760

293( 273 + t ) kg/ma ..*.-. (2)[ taking l-205 kg/m8 ( approximated to l-2kg/ma ) as the weight of standard air at20Ti and 760 mm Hg 1.where

B = barometric pressure in mm Hg atthe time of test, andP, = static pressure in mm HsO.

c) Velocity of air at a point V= 16 000 . . ..- (3)

d) Average velocity of air in the airway P= - m/h . . . . . . (4)where A is the area of airway in squaremetres.

e) Friction loss in airway Pi= o-02 -& x P, mm H& . . . . . . (5)

where L and D are the length and diame-ter of airway in metres, and Pv is velocitypressure in mm HsO.10.13 Temperature-Rise Test

10.13-l M easurement of Cooli ng Air Temperat ureDuri ng Tests - The cooling air temperature shallbe measured by means of several thermometersplaced at different points around the fan motorat a distance of 1 to 2 m and protected from allheat radiations and extraneous draughts. Thethermometers used for this test shall be accurateto -f 0*5OC.

The value to be adopted for the temperatureof the cooling air during a test shall be the meanof the readings of the thermometers taken atequal intervals of time during the last quarter ofthe duration of the test.10.13.2 Measurement of Temfi erat ure-Rise - Thetemperature-rise measurements shall be carriedout by the method indicated in Table 1, immedi-ately after the air delivery test or after the fanhas been run long enough to ensure that the tem-perature-rise has reached a steady state, using thefollowing procedure.

10.13.2.1 Air temperature-rises to be mea-sured by thermometer method [ items (iii) and(iv) of Table 1 ) ] shall be taken at the hottestaccessible surface of the parts, as also on the partswhich are likely to cause injury to any adjacentinsulating material.

10.13.2.2 The method of measurement oftemperature-rise by change in resistance is givenbelow:The temperature-rise t2 - t, ( for copperwindings J mav be obtained from the ratio of the

resistances by the formula t, + 235 4tl + 235 = Fwhere

Rz = resistance of the windings at tem-perature t, ( C ) at the end of thetest, andRI = initial resistance of the windings attemperature t l ( C ).

From the above, the hot temperature ( ta )may be expressed as:t = +- ( t l + 235 ) - 235

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IS : 4894 - 1987APPENDIX B

Clause 9.1.2 )ADDITIONAL INFORMATION TO BE SUPPLIED BY THE MANUFACTURER

B-l. The following additional information inrespect of an electric centrifugal fan shall besupplied by the manufacturer on request: d)e)

a) Power factor,b) Number of blades,c) Type of regulator and

f 19)

positions,Class of insulation,Type of bearings,Instructions for lubrication of bearings,Condenser value ( in case of single-phasefans ), and

number of running h) Fan total efficiency.

APPENDIX CClause 9.1.3

ADDITIONAL INFORMATION TO BE SUPPLIED BY THE PURCHASERC-l. The following information in respect of an,electric centrifugal fan shall be supplied by thepurchaser on request:

c)d)e)

a) Size; f )b) Electric supply details; g)

Air delivery at stated duty;Nature of medium, air or other gases;Atmospheric conditions;Altitude of the place where the fan is to beinstalled; andWhether guards are required.

APPENDIX DClause 10.1.2.1 )

RECOMMENDED SAMPLING PLAND-l. A recommended sampling plan is given in -^-Table 3. TABLE 3 SCALE OF SAMPLINGClause D-l )D-2. CRITERIA FOR CONFORMITYD-2.1 If no defectives are found in the firstsample ( co1 2 ), accept the lot. If the number ofdefectives found is greater than or equal to therejection number ( co1 4 ), reject the lot. If thenumber of defectives found in the first sample isless than the rejection number, take a secondsample of size indicated in co1 3; and if the totalnumber of defectives in the first and secondsample put together is less than the rejectionnumber, accept the lot, otherwise not.

LOT FIRST SECOND REJ ECTIONSIZE SAMPLE SAMPLE NUMBER1) 2) 3) 4)

up to 15 3 3 216 to 100 2101 ,, 200 5 :201 400afI;d above 7

7 :401 7 8 3

NOTE - When the size of the lot is too small as tomake the testing uneconomical, the criteria for accep-tance of the lot may be left to the agreement betweenthe parties concerned.

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