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    BME101/102/001 BASIC ENGINEERING-I / BASIC MECHANICAL & CIVIL ENGINEERING

    Answer Key

    PART-A (10 2=20

    1. classification of I.C. engines

    Based on ignition:

    (i) Spark ignition (ii) Compression ignition. Based on fuel:

    (i) Petrol engine

    (ii) Diesel engine.

    Based on cooling system:

    (i) Air cooled

    (ii) ater cooled. !. Classification of Boilers.

    (i) According to flo" of "ater and gases

    (a) #ire tu$e $oiler ($) ater tu$e $oiler

    (ii) According to pressure

    (a) %o" pressure $oiler ($) &ig' Pressure

    (iii) According to met'od of firing

    (a) Internally fired $oiler ($) ternally fired $oiler *. E!"r#s$%n

    Process "'ic' is commonly used to make collapsi$le tu$es suc' as toot'paste tu$es+ cans usually using soft materials suc' as aluminum+ lead+ tin. ,sually a small s'ot of solid material is placed in t'e die and is impacted $y a ram+ "'ic' causes cold flo" in t'e material.

    -. C s"$n' Casting is t'e process of producing metal parts $y pouring molten metal into t'e mould ca ity of t'e re/uired s'ape and allo"ing t'e metal to solidify. 0'e solidified metal piece is called as casting2.

    3. 0'ree 4a" c'uck+ #our 4a" c'uck or independent c'uck+ 5agnetic c'uck

    6. In up milling+ cutter rotates opposite to t'e direction of feed of t'e "ork piece "'ereas in do"n

    milling + t'e cutter rotates in t'e same direction of tra el of t'e "ork piece.

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    7. S"ress 0'e force of resistance per unit area+ offered $y a $ody against deformation is kno"n as stress. 5at'ematically stress is "ritten as

    f8P9A

    'ere f8 stress + P8e ternal force or load + A8cross sectional area.

    S"r&$n is t'e ratio of c'ange in dimension to original dimension. It 'as no unit.

    ;. )# *$"$es %+ '%%, e.en"

    (i) A good cement s'ould $e uniform in colour and free from lumps. (ii) If a small /uantity of cement is t'ro"n into a essel of "ater+ t'e cement po"der s'ould sink. (iii) 0'e total sulp'ur content of t'e cement s'ould not $e greater t'an !.73 percent.

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    PART-B (3 14=50

    11. C% 6r n $oiler is a lo" pressure fire tu$e $oiler. Steam produced $y t'is $oiler is $elo" ;> $ar. Coal is fed into t'e grate t'roug' t'e fire 'ole and $urnt. As' formed during t'e $urning is collected in t'e as' pit pro ided 4ust $elo" t'e grate. As' is t'en remo ed manually. 0'e 'ot gases from t'e grate pass t'roug' t'e com$ustion c'am$er to t'e 'ori?ontal fire tu$es and

    transfer t'e 'eat $y con ection. 0'e flue gases coming out of fire tu$es pass t'roug' t'e smoke $o and escape to t'e atmosp'ere t'roug' t'e c'imney. Smoke $o is pro ided "it' a door for cleaning t'e fire tu$es and smoke $o . 0'e "orking pressure and steam capacity of coc'ran $oiler are 6.3 $ar and *3>> kg 9'r respecti ely.

    It consists of $oiler mountings suc' as steam safety al e+ "ater le el indicator+ fusi$le plug+ etc.+ for safe operation of t'e $oiler. 0o measure t'e pressure of steam produced $y t'e $oiler a steam pressure gauge is also mounted at t'e top of t'e $oiler.

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    1!. @uclear po"er plant uses nuclear energy from radio acti e element for generating electrical energy. 5ore t'an 13 of t'e "orld s electricity is generated from @uclear po"er plants. It is generally located far a"ay from populated areas.

    In future generation of electricity "ill $e depending on @uclear Po"er Plant+ as it is economical. 1 kg of uranium , !*3 can produce electrical po"er electrical t'at can $e

    produced $y using *>>> -3>> tonnes of 'ig' grade coal or !>>> tonnes of

    oil.

    7%r8$n' 0'e 'eat generated in t'e reactor due to t'e fission of t'e fuel is taken up $y t'e coolant. 0'e 'ot coolant t'en lea es t'e reactor and flo"s t'roug' t'e steam generator.

    In t'e steam generator t'e 'ot coolant transfers its 'eat to t'e feed "ater "'ic' gets con erted into steam.

    0'e steam produced is passed t'roug' t'e tur$ine+ "'ic' is coupled "it' generator. &ence t'e po"er is produced during t'e running of tur$ine. 0'e e 'aust steam from t'e tur$ine is condensed in t'e condenser. 0'e condensate t'en flo"s to t'e steam generator t'roug' t'e feed pump. 0'e cycle is t'us repeated.

    A,9 n" 'es

    =e/uires less space compared to steam po"er plant. #uel re/uired is negligi$le compared to coal re/uirement. #uel transport cost is less. =elia$le in operation. Cost of erection is less.

    1*. GAS 7EL ING E):IPMENTS

    1. as Cylinders

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    Pressure ygen E 1!3 kg9cm!

    Acetylene E 16 kg9cm! !. =egulators

    orking pressure of o ygen 1 kg9cm! orking pressure of acetylene >.13 kg9cm! orking pressure aries depends upon t'e t'ickness of t'e "ork pieces "elded.

    *. Pressure auges -. &oses 3. elding torc' 6. C'eck al e 7. @on return al e

    Ty es %+ ;* .es

    F ygen is turned on+ flame immediately c'anges into a long "'ite inner area (#eat'er)

    surrounded $y a transparent $lue en elope is called C r #r$

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    13.

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    16.

    .

    17 . 5.I a$out 'ori?ontal centroidal a is I 8 $d *91! 8 3 1> 6 mm -

    5.I a$out ertical centroidal a is I yy 8 d$ *91! 8 1.; 1> 6 mm -

    5.I a$out polar a is I ?? 8 I HIyy 8 $d *91! H d$*91! 8 6.; 1> 6 mm -

    5.I a$out $ase I $ase 8 $d *9*8 !> 1> 6 mm -

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    (i) It is prepared $y adding aluminous cement to t'e finely crus'ed po"der of fire $ricks. (ii) 0'e usual proportion is one part aluminous cement to t"o parts fire $rick po"ders. %ig't " e i g ' t m o r t a r: (i) It is prepared $y adding materials suc' as sa" dust+ "ood po"der+ etc.+ (ii) t'er materials could $e as$estos+ fi$res+ coir etc.+ 0'is mortar is sued for sound proof and 'eat proof construction.

    !>. Dams A , . $s $. er9$%#s rr$er %r n % s"r# "$%n %ns"r# "e, r%ss n "#r * s"re . %r r$9er "% 6%*, # w "er %n %ne s$,e %+ $" # "% er" $n *e9e*>

    S tru ctu re o f Dam :

    Upper stream crest downstream

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    Pu r pose of da m s: 0'e stored "ater in t'e dam can $e continuously used for irrigation. 0'e reser oir forms a ery good source for "ater supply for areas "'ere ground "ater

    is inade/uate

    If sufficient 'ead of "ater is stored+ t'en t'at can $e used for po"er generation.0'e reser oir forms a good place for $reeding of fis'+ "'ic' is a considera$le "ealt' for a dam

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    Class ification of dam s:

    Dams are $roadly classified into+ 1 . R i gid D a m s 2. Non rigi d dam s .

    Rig i d d a m s: 0'ese dams are constructed using rigid construction materials.

    0'e construction materials used are+ stone or $rick or reinforced cement concrete.=igid dams are furt'er Classified into+

    1. S ol i d gra v it y d a m 2. A r c h Dam 3. B u tt r e ss d a m

    . !i m " e r a n d s te e l dam

    S ol i d #ra v it y Da m :

    A gra ity dam is defined as a structure "'ic' is designed in suc' a "ay t'at its o"n "eig't resists e ternal forces.

    It is more dura$le and 'as ma imum rigidity. It re/uires less maintenance compared to ot'er types. 0'is type can $e constructed of masonry or concrete. @o"adays+ concrete dams are pre alent.

    Ar c h Da m :

    Arc' dams are cur ed in plan. 0'is structure less 5assi e "'en compared to gra ity dam

    0'e forced e erted $y t'e stored "ater on upstream side "ill $e transferred $y t'e a$utments of t'e arc' dam.

    0'is dam is suita$le for narro" alleys $ut ma4or re/uirements is sound a$utments.

    An arc' dam is economical only "'en t'e lengt' of dam is less t'an its 'eig't.

    B u tt r e ss d a m : A $uttress dam 'as relati ely t'in sections "'en compared

    to a gra ity dam. It consists of a sloping section $uttresses and a $ase sla$.

    0'e sloping mem$rane (#ace sla$) first takes t'e "ater load and transfer to t'e $uttresses "'ic' are specific inter als. 0'e $uttresses in turn transfer t'e load to t'e $ase sla$ "'ic'

    forms t'e foundation part of t'e dam.

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    Tim ber an d S teel Dam :

    0im$er and steel dams are not generally used for $igger dam sections. A tim$er dam is generally adopted for

    temporary re/uirements to enclose certain "ork

    sites or to di ert t'e flo". After t'e main structure is $uilt t'e tim$er dam

    "ill $e dismantled. 0im$er dams are generally made "ater tig't.

    Steel dams are not common in use. But it is possi$le to construct t'e dam "it' steel upto a 'eig't of 13 1; m

    Non R igi d Dam s:

    @on rigid dams 'a e a trape?oidal $asic profile.

    0ypes of @on =igid dams

    $arth D a m s Roc% fill dams .

    a r t' D a m : art' dams are made of soil "it' minimum processing using primiti e e/uipment

    0'ese are $uilt in areas "'ere t'e foundation is not strong enoug' to $ear t'e

    "eig't of a gra ity dam. As t'e construction material of t'e dam is ordinary soil "'ic' is c'eaply

    a aila$le t'e cost of